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Author Topic: Radiator and Kubota engine repair services need in Las Vegas, NV  (Read 3480 times)
Sean
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« on: February 20, 2012, 11:56:30 AM »

Folks,

I need recommendations for a decent radiator shop that can test and possibly re-core a small radiator on a Kubota-powered generator set, and also a shop that could, if needed, hoist the set out of the bus, pull the head, diagnose any issues found there, and install a new head gasket.  Both of these places need to be in or near Las Vegas, NV.

Reason:

As some of you may already know, we are in the Las Vegas area for the next three weeks.  While we are here, I have been helping friends and fellow bus nuts Ben and Karen with their problematic Kubota-powered Power Tech generator.  (Some of you may know Ben as the fellow who is converting a Flxible Starliner, and while that is being done they are living in a Prevost Liberty Classic Lady.)

I have the generator portion of the set, as well as the control system, working perfectly.  However, there are two issues, possibly related or possibly not.

The first issue is that after it has sat for a while, say overnight, the Kubota will overheat shortly after startup.  It would seem that air is ingressing into the system, and a giant air pocket at the thermostat housing (or maybe in the water pump?) is preventing coolant circulation.  Unsurprisingly, the overheat switch, attached to a cooling passage in the head, quickly reaches the set point and shuts the unit down.

Every time this happens, I am able to bleed the system (although sometimes it takes more than one try), refill it, and get the set started.  Once the system has been fully bled, the generator runs fine, will stay running for hours, and has good coolant circulation through the radiator.  Shutting it down and restarting it within a few hours is also usually successful, perhaps because it has not cooled far enough in the daytime temperatures for the pressure to drop sufficiently in the system to draw air into it.

In addition to lots of 15-year-old hoses and clamps, there appear to be a couple of pinhole leaks in the radiator itself.  Any of these might be the source of the air ingress, so we'd like to get the radiator tested and repaired or re-cored along with all the hoses changed out.  Thus the radiator shop recommendation.

The second issue is that, in doing this work, I have noticed the coolant has a slight brown tinge to it.  It is possible that this is just rust and/or dirt from years of neglect, or maybe adding red coolant to a green system, but it is also possible that it is due to products of combustion in the coolant, possibly indicative of a broken head gasket or worse.  If that's the case, it is also possible that this is the source of the gas bubbles in the cooling system.  I have recommended that he get the coolant tested, along with the oil.  If either reveals signs of cross-contamination, then we will need a qualified Kubota mechanic to pull the head and have a look.

Any and all suggestions, recommendations, and comments are welcome.  Post here or feel free to email or PM me.  We want to get this work done between now and around March 13, so that I can be available to go to the shop with him and talk to the techs.  Thanks.

-Sean
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« Reply #1 on: February 20, 2012, 12:58:30 PM »

Does the unit have a coolant recovery system and have you checked it and the cap?

If it sucking air when it cools down because of an empty tank or bad hose, that could form a vacuum in the system which would pull in air.  If any part of the cooling system is higher than the fill cap that would cause the air bubble.  A bad check valve in the cap could force it to suck air from the smallest leak.
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« Reply #2 on: February 20, 2012, 01:09:48 PM »

Len,

Good suggestion, I have added a recovery tank, and changed out the cap. I was loosing coolant too much, too often. That has corrected my situation.

Sean,

Not sure if your genset was sourced from Wrico, but mine was from the PO, I have gotten great advice from Dick.

Is that small radiator worth "reworking", given labor rates it might be better to replace. (?) This comes reluctantly, from a very frugal engineer.

Good Luck.

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« Reply #3 on: February 20, 2012, 01:40:00 PM »

Does the unit have a coolant recovery system and have you checked it and the cap?

Yes and yes.  I've checked all the obvious things.  The radiator is remote, and there is a small tank above the fan belt as well.  Each has a cap.  Radiator cap was bad, so we replaced; unfortunately, I could not source a 14 so replaced with a 13.  Cap on the other tank, which is on the return side, is an 11.  Both caps are functional now.

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If it sucking air when it cools down because of an empty tank or bad hose, that could form a vacuum in the system which would pull in air.

Yes, I think that's what I said.  Which is why I want the radiator tested and all the hoses replaced, hence my request for a good radiator shop.

Quote
  If any part of the cooling system is higher than the fill cap that would cause the air bubble.  A bad check valve in the cap could force it to suck air from the smallest leak.

Again, cap has been replaced.  As far as I can tell, the cap is the highest point in the system, but I can't really see how Liberty ran all the lines.

Not sure if your genset was sourced from Wrico, but mine was from the PO, I have gotten great advice from Dick.

As I wrote, it is a Power Tech.  Wrico and Power Tech are competitors.  Also, this is an engine problem now, not a genset issue, so, while Dick certainly knows the Kubota, there is no reason why any other Kubota service tech could not handle these issues.  Dick's cooling system is a bit different as well -- Power Tech has this weird custom-made belt guard/expansion tank system over the fan belt.  I'm not quite sure what the purpose of having a tank in the return side is, but that's the way Power Tech does it.  They also have a weird custom extension over the thermostat housing, with a bleeder on it and a right-angle take-off for the coolant hose, replacing the stock Kubota thermostat housing cover with hose nipple.  Dick does not use any of these parts, so he would not necessarily be familiar with them.

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Is that small radiator worth "reworking", given labor rates it might be better to replace. (?) This comes reluctantly, from a very frugal engineer.

Well, replacing it would be an option if it is a 100% standard size.  My experience with these sorts of generators is that the radiator hardly ever cross-references to anything you'd find in a radiator shop, and so re-coring is usually the answer.  But here is, again, where a good radiator shop will be able to help us.  We will go with whichever route is cheaper, for sure.

-Sean
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« Reply #4 on: February 20, 2012, 01:54:53 PM »

Sean, simple thought from a simple man!  Red mud or red/brown coolant is quite often the result of someone using stop leak !  Many times stop leak plugs up radiator flues when air is present.  Just a thought, good luck.  John L
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« Reply #5 on: February 20, 2012, 03:07:33 PM »

just a shot. Performance radiator on arville, don't have the # at hand but check your v-mail for it. give Gary@B&B for shop suggestions, 702-873-4415 good luck!
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« Reply #6 on: February 20, 2012, 03:18:02 PM »

Why pull the head pressure test the head on the engine first if it doesn't hold pressure then pull the head,use a vacuum pump to pull the water through on a Kubota takes all the bubbles out and if he is using the wrong antifreeze they will make air bubbles repair the leaks and test IMO that will be what any honest shop will do, 

The odd color is probably from using 2 different types of antifreeze could be rust by not keeping the system maintained over the years

good luck 
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« Reply #7 on: February 20, 2012, 04:40:37 PM »

Sean, an antifreeze sample test might help with the engine decision.  A bad head gasket would probably put the soot level pretty high. 

When my first Series 60 went south (liners sank in block and let combustion past the head gasket), I had the antifreeze analyzed to confirm my worst thoughts about the problem.

Jim
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« Reply #8 on: February 20, 2012, 07:56:26 PM »

  Just a thought, but likely most of the radiator shops are in the phone book or can be found online. Likely someone in the area knows generators or RV's who could recommend the best radiator shop.

  I'm with Clifford, do the simple stuff first before yanking the head off.

  Generally, rapid overheat from cold is a telltale sign of a failing thermostat. If it pushed coolant out it will suck air back in as soon as its shut down. If it were a head gasket one would expect it to show the problem continuously, not momentarily, and only after cold start up. Additionally, a head gasket leak would be leaking coolant into the oil or the cylinder, or both. Coolant in the oil would make a milky appearance. Coolant in the combustion chamber generally creates exteme hard starting (hydraulic lock), followed by thick steam like exhaust. Most auto parts stores sell the test kit to check for combustion byproducts in the coolant, though its known there for some false positives.
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« Reply #9 on: February 20, 2012, 10:45:25 PM »

  Just a thought, but likely most of the radiator shops are in the phone book or can be found online.

Obviously, and I do know how to do that research.  My point in asking here was to hopefully get a recommendation (for or against) from other bus nuts based on personal experience.  I'd rather pick a shop from others' experience rather than from a phone book

Quote
Likely someone in the area knows generators or RV's who could recommend the best radiator shop.

Well, yes, but if I knew someone in the area who knows generators, I wouldn't be asking here.  As for knowing RVs, I generally don't trust conventional RV service establishments for anything -- if they can't look it up in the OEM documentation for a name-brand RV, they are usually no help and sometimes worse.

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Generally, rapid overheat from cold is a telltale sign of a failing thermostat.

Sometimes, yes.  In this case, the problem happened with no thermostat in the housing at all -- apparently it had been removed due to failure on some previous occasion, and Ben had not gotten to installing the replacement, although he had it in his kit.  I opened the thermostat housing after the first failure as part of my diagnosis, cleaned everything up, and while I was in there I installed a brand new OEM Kubota thermostat, so I don't think the thermostat is the culprit here.

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... If it were a head gasket one would expect it to show the problem continuously, not momentarily,

Well, that's my guess, too, which is why I said these issues may not be related.

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... Additionally, a head gasket leak would be leaking coolant into the oil or the cylinder, or both.
...

Not necessarily -- it depends on exactly where the gasket is damaged/leaking.  It is possible for a leak to be only, say, between a cylinder and a cooling passage, but not an oil passage.  If the leak was minute enough, then normal coolant pressure might not be enough to force coolant into the cylinder, whereas combustion pressures could still force combustion gasses into the coolant.  That said, I think you are correct that if this was happening, then a gas bubble would form during operation that would almost immediately cause a shutdown, and we're seeing the unit run for hours without trouble once it is bled.

I am fairly convinced that the only real problem we have here is air ingressing into the cooling system during the cool-down process, most likely through old hoses or clamps, poor cap fit, or pinholes in the radiator.  The off color of the existing coolant is probably an unrelated issue, but I though it worth mentioning here.

Based on all the recommendations so far, we are going to get the cooling system work done at a local radiator shop, and send a coolant sample out for analysis.  We'll only pressure-test the head if that comes back with combustion products in it.

Would still like any recommendations for local radiator service, besides the one from Van whom we will call in the morning.  I am pretty convinced that the radiator will need to be replaced or re-cored; not only am I seeing pinhole leaks, but it's 15 years old and has been subjected to tap water and who knows what else -- if it's anything like mine was at that age, it's probably half blocked, too.  Plus I'd like a professional shop to backflush the whole system, replace all the hoses and clamps, and refill and bleed the system with a vacuum pump as Clifford suggests.

Thanks.

-Sean
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« Reply #10 on: February 21, 2012, 08:28:33 AM »


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... Additionally, a head gasket leak would be leaking coolant into the oil or the cylinder, or both.
...
Not necessarily -- it depends on exactly where the gasket is damaged/leaking. 

  Not really. If there is a loss of coolant that put air into the system, that lost coolant had to go somewhere. Even if the cap was bad, or there were hose leaks, the only way to allow air into the system, is after an equivalent volume of coolant loss. If its not on the ground and isnt in the oil, its a pretty sure bet it went out the tail pipe. However...

  If its truly a closed system, the cap should vent into the overflow bottle, with the vent hose fully extended to the bottom of the overflow bottle, and fully immersed coolant. If the vent line sucks air after cool down, that air is going straight into the cooling system. If these Kubotas are real sensitive to air in the system it probably ddent take much. If its a custom setup, perhaps the bottle isn't large enough, the hose isnt fully down in the coolant, the hose may have a break or crack somewhere, etc.. I would inspect that area in great detail. Engines usually have to cool below 100F before the cooling system will draw back any significant volume from the overflow, after everything else has contracted. That may be why it doesnt show its ugly head after a few hours being shut down, but does after an overnight.

 

     

  I share your disdain with RV centers, however, most do not work on generators, they send them out to someone. A few calls to various shops and their recommendations should point you to someone honest. Notice I didnt say "qualified", lol.

  I would suggest a call to Wrico. That outfit seems to be the most highly respected shop in North America. While they certainly cannot fix your problem over the phone, they likely can give you much better suggestions of where to look, and may possibly know a good shop in that area. Another place would be Power Tech themselves. The few times I have spoke to them I found them very helpful.

  Also, pressurising the cooling system to 25 psi should find any leaks, block cracks, blown gaskets, or anything else than cant withstand the pressure.

 
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« Reply #11 on: February 21, 2012, 08:50:26 AM »

Sean is on the right track a call to Dick Wright about a Kubota engine problem would be a waste of time he just buys the complete engine he does no repairs doesn't have a clue except on his packages and before you guys jump on me Dick and I are friends and have been for a long time

good luck
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« Reply #12 on: February 21, 2012, 09:44:52 AM »

... If its not on the ground and isnt in the oil, its a pretty sure bet it went out the tail pipe. ...

Ahh, I see I left out an important detail: it's on the ground.  Each time the system has overheated in this way, enough coolant blew out the relief to overflow the recovery tank, and we lost a cup or two every time.  After I bled the system, we'd then have to top up the radiator, making up for what was lost.

... a call to Dick Wright about a Kubota engine problem would be a waste of time he just buys the complete engine he does no repairs doesn't have a clue except on his packages ...

I agree with Clifford on this, as I wrote in my response to Gary above (http://www.busconversions.com/bbs/index.php?topic=22932.msg252083#msg252083).  Dick and I also go way back, and some of you may know that when I had to completely rewire my own Fidelity/Kubota set, I rewired it to Dick's standards, and also used his safeties, muffler, and mounts.  But he is a generator guy, not a mechanic, and there is no reason why he would be any more qualified to diagnose a cooling problem than a tractor dealer, and the latter is going to be easier to get to here in Vegas.

Power Tech has, indeed, been helpful, and some insight from them did help me to resolve the issue with the voltage regulator.  But here again, they are not going to be able to diagnose a cooling system from 3,000 miles away.  They could, perhaps, answer my question about why the weird two-tank arrangement, but that's largely irrelevant to the current problem.

Incidentally, I am rather unimpressed with Power Tech's controls.  In particular, the overtemp safety is not fail-safe, as it is, for example, in Dick's design.  So if the wire comes off the overtemp sensor, the safety is defeated and the set can overheat without shutting down.  Lots of things can cause a little wire like this to break -- on my own set, the wire to the temperature sender for the gauges broke from years of vibration -- and then you'd have no overheat protection without knowing it.  In addition to destroying an expensive genset, this kind of thing can lead to fire and the loss of the whole coach.  So shame on Power Tech for taking such a shortcut.

Similarly, whereas Dick's design uses a tiny handful of reliable and readily-available parts (two switches, two relays, two safeties, and a fuel solenoid), Power Tech uses a proprietary circuit board with four relays and a bunch of discreet components.  Add to that the weird belt guard and tank arrangement plus the funky extension above the thermostat housing, and now you've got a bunch of parts that can only be supplied by Power Tech themselves -- which is, perhaps, their intent.

I went through this same headache working on Chris and Cherie's Onan in Arcadia a couple months ago.  What ought to have been a simple circuit using a few discreet parts was instead printed on some proprietary Onan board, which now has failed in a way that can't easily be repaired.  Onan's way of locking you in.  I've suggested to them to ditch the Onan board and I would design them a start/stop system using just the pair of relays and switches, but they are preoccupied with other issues at the moment.

The more I work on other people's generators the greater my appreciation for my own ancient set, which has a completely mechanical governor and is transformer regulated.  Eventually my rings will wear out or perhaps the bearing in the generator head will go, but otherwise there's hardly anything electromechanical to break, and there's nothing to adjust.

-Sean
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« Reply #13 on: February 21, 2012, 10:30:47 AM »

Sean, those guys at a trailer refrigeration place like Great Dane in Vegas are top notch on the Kubota engines if you can get one to look at it fwiw

good luck
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« Reply #14 on: February 21, 2012, 10:46:57 AM »

Sean, the symptom of filling the overflow bottle and then running the antifreeze on ground sure sounds like my Series 60 problem where the liners sank in the block and let the combustion past the head gasket.

In the case of the Kubota, it probably does not have liners, but a blown head gasket would give the symptom you are describing.  The head gasket would have to be compromised between the cylinder and the water jacket for this to be the same problem.  The sure signal would be a grayish color to the antifreeze.  In my case, I drew some antifreeze out of the overflow and let it sit in a glass jar.  After about a day, the soot settled in the bottom and was very obvious.

May not be the problem, but the symptoms sure sound the same to me.

Jim
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« Reply #15 on: February 21, 2012, 11:26:29 AM »

FWIW, which is not much, when I had a similar problem (albeit with a race engine in a 1961 Lotus 7) it was a crack in a cylinder wall.  It defied diagnosis till it was put on an engine dyno with a see-through cooling system - 100 gallon water tank.  It only had a problem when it was hot, it passed all the tests you could imagine cold.

Brian
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« Reply #16 on: February 21, 2012, 01:07:58 PM »

Jim and Brian,

I am wondering how, if this is the problem, the engine is running fine for hours and hours once it is bled. In fact, once it has been running fine, it will re-start just fine too, as long as it is still somewhat warm.  It's only after it cools down overnight that we get the air bubble.

I would think that if combustion gas was blowing past the gasket into the coolant, that we'd get a gas bubble while running, followed by overheating and a shutdown.  No?

-Sean
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« Reply #17 on: February 21, 2012, 01:42:29 PM »

When is it putting the fluid out onto the ground?  I thought that was when it was hot, but you say it runs fine.  So - it's running fine, then it's off, it gets cold, it gets air-locked (where is still a mystery, yes?), it starts up again, it over-heats, it dumps fluid out.  You have some tiny weeps in the rad, but not enough to bother it while it's running.  If full pressure won't spray coolant out all over and make a mess, the vacuum created by cooling down probably won't pull in a ton of air.  So I look for another source of air - combustion or cavitation.  Most cooling systems are self-bleeding, or should be.  The design is such that air naturally rises to the highest point, which is often where the radiator cap is and where coolant is added, but not always, sometimes the header tank on top of the radiator, sometimes a separate header tank.  That air is supposed to create a "pressure spring" to help keep the coolant from cavitating, hence the pressure cap.  Perhaps an internal bleed passage is blocked.  The water pump should definitely be able to self bleed itself, and the cooling system would usually have a gravity head of water pressure above the input to the water pump from water in the radiator or in the block.  It's a remote rad, I think you said, how is the top of the radiator supposed to self-bleed back to the header tank?  You have coolant recovery tank - is that a pressurized tank or atmospheric?  Is the rad cap on the header tank (the one that feeds the recovery tank) equipped with a top sealing ring?  If the tank is pressurized, is it's pressure cap at the same or lower PSI than the main one?  FWIW when I run a pressurized coolant recovery tank, I run a solid seal cap on any other fill points.

The story about the cracked cylinder is just to point out that cracks sometimes are hard to diagnose from outside the engine, they can defy logic because sometimes they close up tight when they are cold, and sometimes they close up tight when they are hot...  But I would also expect the thing to fail while running if it was head gasket or a crack.  Which is why I am now thinking a blockage somewhere.  Anyway, random ramblings, this problem has bugged me all day.  Sorry I don't know a shop in LV, I've never actually been to LV...   Cheesy

Brian
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« Reply #18 on: February 21, 2012, 02:29:15 PM »

Brian,

Thank you very much for the detailed response.  I appreciate the help.  I will try to answer your follow-up questions as best I can.  The genny is no longer in front of me; we are still at Lake Mead and Ben and Karen have returned to Las Vegas with their bus.  Ben tells me he has an appointment at a radiator shop this afternoon.

When is it putting the fluid out onto the ground?  I thought that was when it was hot, but you say it runs fine. 

Let me clarify the sequence.

If I don't first bleed the system, from a cold start, I will see the head rapidly heat up, with virtually no rise in temperature at the thermostat housing or bypass line back to the water pump.  It very quickly reaches the setpoint of the temperature safety and the engine shuts down.  Almost simultaneous with the shutdown (had to say if just before or just after), the radiator cap will let so much coolant into the recover tank that it overflows.  I'm guessing about two cups or so.

If I bleed it first, which seems to require opening at least one bleeder with the engine running until just fluid comes out, then I see good coolant flow, as evidenced by steadily rising temp, through the thermostat housing, and then on to the radiator once the 'stat opens.  Once I have good coolant flow to the radiator the unit runs normally indefinitely and no fluid comes out anywhere.  We noticed two perpetually wet spots on the rad, which is why I am guessing is has some pinhole leaks.

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So - it's running fine, then it's off, it gets cold, it gets air-locked (where is still a mystery, yes?),

Yes.

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... it starts up again, it over-heats, it dumps fluid out.

Yes, as described above.

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  You have some tiny weeps in the rad, but not enough to bother it while it's running.

Does not seem like it.

Quote
  If full pressure won't spray coolant out all over and make a mess, the vacuum created by cooling down probably won't pull in a ton of air.

Hmm, OK, that makes sense.  But I will tell you that before I changed all my hoses and clamps on my main cooling system (on my Detroit, not the genny), the system ran fine with no leaks at all when it was warm, but after really cold nights, we'd find coolant on the ground under the coach, sometimes a lot of it.  It turned out that differential contraction of the materials, wherein the hose barbs were contracting faster than the hoses and clamps in the cold, was enough to let gravity alone force coolant out through the resulting gaps.  So it seems reasonable to me that something similar could be happening here, where everything is tight once the genny is at running temperature, but as the temperature drops into the low 40s or high 30s here at night, that same sort of differential contraction is letting air into the system.  That is, of course, just a working theory and not confirmed by any direct observation.

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... So I look for another source of air - combustion or cavitation.  Most cooling systems are self-bleeding, or should be.

Agreed, and my generator setup, based on exactly the same Kubota engine, does work this way and I don't even have any bleeders on the system.

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...  The design is such that air naturally rises to the highest point, which is often where the radiator cap is and where coolant is added, but not always, sometimes the header tank on top of the radiator, sometimes a separate header tank.

This system actually has two tanks, each with a pressure cap.  There is the header tank on the remote radiator, which is connected to an overflow tank at atmospheric pressure.  Then there is a separate tank near the engine, with another pressure cap but no overflow.  The tank near the engine appears to be plumbed with a tee into the coolant return just before it reenters the block.  It is higher than everything on the engine, but lower than the radiator tank and some of the hoses.

The tank near the engine is equipped with an 11 PSI cap and we have not seen that one release at all.  The tank on the rad was equipped with a 14 PSI cap.  However, the first time we saw this cap release pressure, not only did some go into the overflow tank, but some came spilling out around the cap, too, so I replaced it.  I could not source a 14 locally so I settled for a 13.  The 13 has a top gasket, which I did not notice on the 14

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  That air is supposed to create a "pressure spring" to help keep the coolant from cavitating, hence the pressure cap.  Perhaps an internal bleed passage is blocked.  The water pump should definitely be able to self bleed itself, and the cooling system would usually have a gravity head of water pressure above the input to the water pump from water in the radiator or in the block.

Perhaps this is the purpose of the extra tank on the return side.

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It's a remote rad, I think you said, how is the top of the radiator supposed to self-bleed back to the header tank?

Not sure I understand this question.  The radiator, while remote, is a conventional style with a tank soldered to the top and a pressure cap.  This would appear to be the high point of the system although there may be a very short bit of hose run, intended to let the genny slide in and out of the bus, that loops to this height or just above it -- hard to tell.

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  You have coolant recovery tank - is that a pressurized tank or atmospheric?

Atmospheric.

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  Is the rad cap on the header tank (the one that feeds the recovery tank) equipped with a top sealing ring?

Good question.  The 13 PSI cap I just installed has one; the 14 PSI cap it replaced apparently did not.  That cap was put on by some previous technician, so it's unclear what the design calls for.

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  If the tank is pressurized, is it's pressure cap at the same or lower PSI than the main one?  FWIW when I run a pressurized coolant recovery tank, I run a solid seal cap on any other fill points.

Hmm.  So with an unpressurized recovery tank, should I go back to the gasketless 14 PSI cap?

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The story about the cracked cylinder is just to point out that cracks sometimes are hard to diagnose from outside the engine, they can defy logic because sometimes they close up tight when they are cold, and sometimes they close up tight when they are hot...  But I would also expect the thing to fail while running if it was head gasket or a crack.

Yeah, that's my thinking, too.

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  Which is why I am now thinking a blockage somewhere.

OK.  That would not surprise me, since the coolant looks crappy and when I pulled the thermostat housing off I could see light debris in the coolant (although hard to say it was not just old gasket sealer from the stat housing).  My first recommendation to Ben was a backflush and refill with proper coolant, in addition to replacing the hoses and testing the rad.

I welcome any further thoughts you may have based on the answers I just provided.

-Sean
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« Reply #19 on: February 21, 2012, 08:13:53 PM »

Sean have you considered a collapsed inner liner on a radiator hose?
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« Reply #20 on: February 22, 2012, 05:44:19 AM »

Sean have you considered a collapsed inner liner on a radiator hose?

  Hahahaha, thats one you dont hear very often these days. The lower hose could also be missing the spring.

  For those who dont know, the water pump wants to draw coolant from the bottom of the radiator into the pump, but cannot do so unless the thermostat is open, which then allows flow from radiator to pump, pump to engine, engine to top of radiator. When an engine is cold there is no coolant system pressure, and suction from the pump can collapse the hose. A good pump can keep that hose collapsed no matter how hot the engine gets. Once it blows and you shut it down, if you restart it it often times has enough residual pressure to keep the hose inflated and, well, it can cause a lot of head scratching.

  I once had a lower hose that got an embolism. The inner section of hose got a leak that was retained by the outer layer. Pressure forced coolant within the two, and the inner liner separated from the outer part of the hose and pulled away, until it completely choked off the lower hose. Externally the hose looked fine, it was only when I squeezed it, you could feel this odd lump inside. That one had me scratching my head for a while.

  Brian may have hit on the right idea, you dont want two pressure caps. You should only have a bleeder at the remote radiator, with no pressure cap. The Pressure cap should be highest point near the engine, and overflow bottle should be adequate volume plumbed off the pressure cap. Alternatively, many later model vehicles put the pressure cap directly on the expansion tank, making a 100% closed system. Many often run a bleeder off the T stat housing to the tank as well, making a self bleed cooling system.
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« Reply #21 on: February 22, 2012, 09:16:18 AM »

In the progression of easiest/cheapest to difficult/expensive with this problem,  I think installing new hoses first would be a good idea.  Cut open the old hoses lengthwise to see if by chance they have delaminated.  Sounds like the hoses are due for replacement anyway.
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« Reply #22 on: February 22, 2012, 09:49:19 AM »

So just a quick update here:

I am still at Lake Mead, although we will be rolling down the hill to B&B Coach to fix a problem of our own later today (http://ourodyssey.blogspot.com/2012/02/not-what-we-meant-by-pop-rivets.html), and Ben brought his bus to a radiator shop in town yesterday afternoon.  I spoke to the tech on the phone to brief him on what we had already done and the symptoms.

They removed, inspected, and pressure tested the radiator, which turned out to be in good shape.  They also removed and inspected all hoses, which also turned out to be fine.  What had looked to us like age cracking in the hoses was actually in some clear coat that Liberty had applied to the whole system, hoses and all.  We also learned that, while it is marked as an 11, the cap on the lower accumulator tank in the return line has been blocked off and so is actually solid, so the 14 cap on the radiator header at the high point in the system is the only actual pressure relief cap, connected to a proper (atmospheric) expansion tank.

The shop drilled out the bleed hole in the thermostat to a larger size, and pressure tested the entire system, which passed.  They backflushed the cooling system and took a sample of the old coolant for analysis.  As of the last I heard last night, it was all back together and working.

Of course, only an overnight cool down will tell us if a backflush, fill, proper bleed, and larger bleed hole in the stat will have cured the problem.  As of this writing I have not heard back from Ben as to whether he's tried it yet today.  I will update here when I learn more.

Thanks for all the help.

-Sean
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« Reply #23 on: February 22, 2012, 09:57:26 AM »

Get the air out those little guys they are not much of a problem for 20 to 25 thousand hrs I never had to replace a head or gasket on one but they are hell to bleed that is why I use the vacuum pump, that is the only way you can bleed the model that does not use a water pump and the 70/30 mix fwiw

good luck
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« Reply #24 on: February 22, 2012, 10:21:13 AM »

Quote from: artvonne
  Brian may have hit on the right idea, you dont want two pressure caps. You should only have a bleeder at the remote radiator, with no pressure cap. The Pressure cap should be highest point near the engine, and overflow bottle should be adequate volume plumbed off the pressure cap. Alternatively, many later model vehicles put the pressure cap directly on the expansion tank, making a 100% closed system. Many often run a bleeder off the T stat housing to the tank as well, making a self bleed cooling system.

I don't why you say this. Every Setra I've ever had has had 2 pressure caps. I know they've been doing it since 1986 (the oldest I have worked on) and probably longer than that and it works for them.
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« Reply #25 on: February 22, 2012, 10:39:19 AM »

BK, the reason I suggested that was that, in this case, the cap marked with the lower pressure (which turned out to not be a pressure cap after all) was not the one that the overflow recovery was hooked up to.  All things being equal, the lower pressure cap would normally blow off first, and in this case, the higher pressure cap would never let coolant out to the overflow tank.  When things are old, maintenance is spotty, things are changed from the OEM install, parts get replaced with what's at hand, and most importantly - the thing ain't workin' right - you tend to try to go back to first principles and look for root causes of problems.

I confess that bleeding cooling systems, and designing them so they self-bleed, is a bit of a bug with me.  I had a race car that you had to "burp" the cooling system on.  That consisted of picking it up by the tail and hanging the entire car at a 45 degree angle, nose down, so that the air bubble would come out of the front rad.  That was indeed a PITA...   Roll Eyes and I fixed it in a hurry!

Brian
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« Reply #26 on: February 22, 2012, 07:20:30 PM »

  I had a race car that you had to "burp" the cooling system on.  That consisted of picking it up by the tail and hanging the entire car at a 45 degree angle, nose down, so that the air bubble would come out of the front rad.  That was indeed a PITA...   Roll Eyes and I fixed it in a hurry!

Brian

  I dont know if the Italians are any brighter than the Brits, but the 308 never had much problem bleeding. And the early ones like mine didnt even have a bleeder at the T-stat.

  Dont know anything about a Setra either. All I can say is the simpler the system, the less  problems, the easier the diagnosis. Why hard to bleed engine designs dont come with self bleeding coolant systems is beyond me. Its not like its rocket science.
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« Reply #27 on: February 22, 2012, 08:20:43 PM »

  I dont know if the Italians are any brighter than the Brits, but the 308 never had much problem bleeding. (snip)

      Something about six of one and half a dozen of the other strikes a famiilyah note.  On 1987 and 88 Range Rovers sold in the US, you had to drive the front wheels up onto a 4-post lift and raise it at least 30 degrees in the air.  Otherwise air trapped around the intake manifold and top of engine would never burp out.
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« Reply #28 on: February 22, 2012, 08:31:44 PM »

      Something about six of one and half a dozen of the other strikes a famiilyah note. 

  I dont know except everything I ever owned that was British seemed to need to be flipped upside down to get the air out. And lets face it, the Japanese copied a great deal of British technology, so its not a big surprise their engines air lock and need some goofy procedure to get the air bubble to cooperate.
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« Reply #29 on: February 23, 2012, 04:35:07 PM »

I saw a very similar problem on a Country Coach.   These systems are susceptible to ingesting air because the radiator and header tank are marginal for height.   I did not understand if you changed both the radiator cap and header cap.   In the example that I diagnosed, the problem was the header tank cap.   That was only after the owner changed the thermostat, waterpump, and was ready to pull the head.

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« Reply #30 on: February 23, 2012, 07:36:00 PM »

I agree Ed the header cap should be an old style non recovery cap


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« Reply #31 on: February 24, 2012, 12:27:26 PM »

The last update on this for a while is that Ben and Karen split for Hawaii before he got a chance to test whether the work they did at the radiator shop cured the problem.  Also, he could not get hold of a test kit before he left so even the coolant testing will have to wait a couple weeks for them to return.

I am fairly convinced that the last remaining problem here was bleeding all the air out of the system.  Clearly I was unable to do this in the field without the proper tools, or the ability to tilt the bus to whatever weird angle is needed to get those final air pockets out.  I am hoping that the process they used at the radiator shop was more successful.

When they get back on March 5 or so we will get a chance to re-test, and I will update the thread here if there is still a problem.

-Sean
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