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Author Topic: Need more help: 8V92 Cooling  (Read 5020 times)
Hobie
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« Reply #30 on: August 08, 2007, 07:10:39 PM »

Something I found..

"The more familiar way that almost all my fan-clutches have failed has been the opposite; they stay loose all the time, so that they're never spinning near engine speed. You can test for this by taking the truck out for a drive to get it warmed up, leaving it running, popping the hood, and then watching the fan as you shut off the engine. A good fan clutch should stop spinning almost immediately; a failed fan-clutch will keep spinning a few turns after the engine is shut off. When you've turned it off and it's still hot, a good fan clutch will give a lot of resistance to being turned by hand, while a bad fan clutch will spin more freely."
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« Reply #31 on: August 08, 2007, 08:29:26 PM »

Sean,
The fans I have are just like yours, they remind me of when thermostatic fan clutches came out in the 60's on the factory hi-performance cars, like I said, just bigger.

Footnote: turning the hub on each has resistance, but I don't have them mounted like you do where you can turn blades, I just turn the hub and they feel "stiff".  And as you can see, there is a small bi-metallic spring on the front that lets these lock-up with heat.
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Well no longer a bus nut, but over the years I learned a lot here and still come back to see what I can apply to the conversion of my KW T2000 for hauling my Teton fifth wheeler.
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« Reply #32 on: August 08, 2007, 08:33:10 PM »

Sean,

It appears that you are sure the fan is viscous. I agree and the hub cooling convinced me. There is no other purpose for hub cooling fins than to cool a liquid.
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Don4107
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« Reply #33 on: August 08, 2007, 09:52:52 PM »

Sean,

After much grief with fan clutches in a couple of tow vehicles and a med duty truck I have come to the conclusion that the only good fan clutch is one laying on the shop floor replaced by a direct drive hub.  Maybe in your bus they are there to allow for quicker warm up or to maintain coach heat when idling or going down hill or to lessen shock loads on the fan drive,  but I really don't understand their use in a bus.   In front engine vehicles they allow natural flow to cool when available.    That never happens in a rear engine bus. 

Buy the way, little know factoid, some fan clutches in cars and trucks have a built in mid to high RPM cutout.  I noticed on pulls that slightly lugging up the grade ran cooler than shifting down to keep RPMs up, thus my investigation into how the fan clutches really worked.  The engineering said if the 'average' vehicle is running above a predetermined RPM there should be enough natural air flow.  Not so when towing a couple times the vehicle weight at low speed uphill.   I solved two major overheating tow rigs just by putting in direct drive fans.  Went from needing to constantly monitor heat gauge to almost forgetting about it with no other changes.  You could also hear the fan roar, something that never happened with the clutch. 

If you get a good look at the clutch both front and back to see if there is ANY evidence of leakage around the little shaft attached to the bi metal actuator or where the drive shaft enters on the other side you have trouble.  It takes very little loss of fluid to leave you with a clutch that will slip.

Since you are not concerned with keeping paying passengers warm or saving a few drops of diesel I would opt out of the fan clutch club unless someone can give you a very good reason to keep them.  But thats just the redneck in me talking. Smiley The PC in me says just say NO. Smiley

Hope you get back to carefree busing soon.

Don
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Don 4107 Eastern Washington
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« Reply #34 on: August 09, 2007, 12:04:43 AM »

Sean- I would HIGHLY recommend you just plainly remove that viscous fan and use a solid mount continuous fan.  All reasons previously mentioned are valid.  I had a viscous fan in one of my trucks (6V-92TA), and noticed that when it heated up would work great at up to about 1800rpm where you could here the fan come up to speed. If you went above 1800rpm, the fan would disengage causing the engine to heat up.  Probably what is happening to you with keeping the engine revved up.  I have a gear drive on my bus so that with a reverse rotation engine (V-drive) I use a standard 8 blade right handed aluminum fan.  From what I can tell with your picture, it looks like a 6 blade fan.  I would suggest a 8 blade fan of the same diameter with at least a 3" pitch going through a direct drive solid fan hub.  The bit more fuel that is burned will be more than offset by the simplicity of having no fan clutch, and that you'll be getting maximum cooling.  The thermostats in the 8V-92TA will keep the engine warm enough in winter.  All viscous fans when hot at idle give the impression of working correctly-that's why when you walk behind the bus you do feel them blowing.  But believe me, at engine speed, they are not doing as good a job as you'd think they are. Good Luck, TomC
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Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.
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« Reply #35 on: August 09, 2007, 03:58:21 AM »

Sean if you do need a new fan clutch you may want to look at the Horton pneumatic i have one on my Eagle and they are great when going on dusty roads because you can turn it off  to keep the dust down or in the winter to keep the engine warm and it has a manual lockup in case of any problems with the air supply.I am sorry you are having so many problems but have a good day
« Last Edit: August 09, 2007, 04:00:06 AM by luvrbus » Logged
DrivingMissLazy
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« Reply #36 on: August 09, 2007, 05:10:52 AM »

If you plan on doing any cool or cold weather driving, I suggest you consider keeping some kind of clutch on the fan. On my 8V92 the fan was controlled by external line. I suspect it was temperature, but I never found out for sure.
In order to try and eliminate an over temperature problem, I had the clutch removed and the fan replaced with a larger fan by the boys up in Oregon. It did help my overheating problem some, but never really cured it.
When I got back to WV the next winter and the temperatures dropped down into the 20's and 30's I had a significant problem getting the engine up even close to normal operating temperatures. It would stay down in the120-130 range. Not warm enough for the heater to warm the bus. I had to run the Webasto to get some heat. I finally started putting a throw rug up against the radiator to block out the air which did help a lot. I would completely block the radiator and the temperature would then climb up to the 180 mark. I just watched the temperature and when it started getting warmer outside and the engine temperature started to climb above the 180 mark I would stop and remove the throw rug.
Richard

PS That is why you see so many OTR trucks with big black covers over the radiator. Usually adjustable so that they can be used to only cover a portion of the radiator as needed.
« Last Edit: August 09, 2007, 05:21:19 AM by DrivingMissLazy » Logged

Life should NOT be a journey to the grave with the intention of arriving safely in an attractive and well preserved body. But rather to skid in sideways, chocolate in one hand, a good Reisling in the other, body thoroughly used up, totally worn out and screaming:  WOO HOO, what a ride
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« Reply #37 on: August 09, 2007, 08:05:39 AM »

Years ago, the engine manufacturers went to shutterless cooling systems-meaning that the thermostats now on engines are good enough where you don't need any kind of radiator shutters (the metal shutters that would open and close automatically).  If you're travelling in extreme cold-like below zero, then a radiator winter front (canvas cover) will keep the temp up since the frontal movement of the truck will keep the engine to cool for heat.  If you do drive in a winter situation, I would run during summer with the fan on continuously, and then on thermostatic control during winter.  Best yet is to have a air powered on/off fan clutch then have a dash switch that you can turn on the fan from the drivers seat. Nearly every truck I sell has that feature.
When I was driving, I had the fan control switch on the dash and before I got to a hill climb I would switch on the fan to pre-cool the radiator for the pull.

Sean-  If you don't want a continuous running fan, which might be too much for winter and create dust on dirt roads, install a true on/off, or a two speed fan that drags when off.  You typically don't want a true on/off since with a side mount radiator, there isn't any kind of flow through it-you should have one that drags in the off position.  If you do go with a on/off, you could wire it with a off-on-on switch, so that off would be exactly that, first on could be thermostatic automatic control and the second on could be continuously on.  But once again I HIGHLY recommend you get away from the viscous fan!!!  Good Luck, TomC
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Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.
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« Reply #38 on: August 09, 2007, 08:51:02 AM »

Thanks for the excellent explanation Tom. I have to reiterate what many others have said, It is a pleasure to have you and your knowledge on the board.
Richard
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Life should NOT be a journey to the grave with the intention of arriving safely in an attractive and well preserved body. But rather to skid in sideways, chocolate in one hand, a good Reisling in the other, body thoroughly used up, totally worn out and screaming:  WOO HOO, what a ride
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« Reply #39 on: August 09, 2007, 10:04:39 AM »

Well, the discussion seems to have narrowed down to fan speed.  I'm unconvinced that this is the problem.  First off, these are the same fans I've always had.  So this can't be the problem unless one of the couplings has stopped working properly.  I'm still hunting for an optical tach to confirm this, but visual inspection shows the fans to be running at pretty much full speed.

That being said, if it is the fans, fixing the bad coupling(s) will be the easiest course of action.  And I do have the offer of identical take-outs, should one or both couplings be bad.  I say this because, of course, it's a weird German bus with weird fans and couplings -- this is probably not a case of calling Luke at US Coach or Joe's Radiator shop and giving them a diameter and speed and asking for a fan, or a coupling.  It's much more likely that I will have to have all the mounting hardware, up to and including the (metric) fan pulleys, removed and completely replaced with something that will accept more common US-spec fans.  To borrow/corrupt a nautical term, that will cost at least a "bus unit" (=$1,000) to have done, bearing in mind that I have neither the skills nor equipment to do this sort of fabrication myself.

The second-easiest solution, if fan couplings prove to be the source of the problem, would be for me to have a welder tack the shafts to the housings -- no easy feat, since I think that's going to be stainless to aluminum.

All that being said, I am leaning towards the silicate gelation theory.  Having the radiators flushed out is a (relatively) cheap and easy thing to try.

Does anyone know what the recommended caustic solution is for removing silicate deposits?

-Sean
http://OurOdyssey.BlogSpot.com
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« Reply #40 on: August 09, 2007, 10:42:38 AM »

I believe DD does not recomend flushing with anything but low pressure water - FWIW
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« Reply #41 on: August 09, 2007, 11:31:07 AM »

I believe DD does not recomend flushing with anything but low pressure water - FWIW


Thanks, Niles.  I was working from this, from Detroit publication 7se390, "Cooling System Technician's Guide," page 11, "Silicate Gelation":
Quote
... The only way to remove small amounts of this gel is to agitate the components in a caustic solution. Care must be taken so that the O-rings, gaskets, seals, and aluminum parts are not damaged. ...


It does not say whether or not the radiator is one of the "components" which can be agitated in a caustic solution.  Nor does it say what specific caustic agent should be used.  So I was hoping someone here would know...

-Sean
http://OurOdyssey.BlogSpot.com

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« Reply #42 on: August 09, 2007, 12:39:08 PM »

Now I see Sean - okay, first I found this scary bit of instructions:


Unfortunately, there are few effective methods for cleaning the gel from an already-clogged system. Radiators must be removed and sent out for a thorough cleaning. The engine must be flushed with a caustic solution. The gel is not water soluble, so flushing with water alone will not work


But try this Penray # 1-800-322-2143 for the products below - HTH

Penray 2001On-Line Cooling System Cleaner• Cleans diesel engine cooling systems while they remain in service• Eliminates light scale and limited corrosion formation• Removes harmful mineral and oxide deposits• Excellent alternative to in-shop cleaning

Penray 2015 Twin Pac Off-Line Cooling System Cleaner and Conditioner• Combines 2010 Cleaner and 2011 Conditioner• Removes harmful scale and sludge deposits from the entire cooling system• Removes corrosion deposits• Removes green slime• Removes oil deposits• Flushes the cooling system of loosened deposits• Removes any accumulated oil• Conditions the metal surfaces
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« Reply #43 on: August 09, 2007, 12:59:40 PM »

Niles,

Thanks, great information.

I'm going to look for a shop that can (1) test the pump and (2) flush the system, possibly with the products you mentioned.  It looks like there is a Detroit dealer in Liberal, KS, which is on our way east.

-Sean
http://OurOdyssey.BlogSpot.com
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« Reply #44 on: August 09, 2007, 01:10:51 PM »

Sean,

With what I can see in the above pixs, you have the basics to built direct drive hubs.  If you use the take out clutches you should saw off and keep the hubs where they bolt to the drive pulley/shaft before you toss the old clutches.  I can't tell whether the ring where the fan bolts to the clutch is a reenforcement or molded into the fan.  They would not take much space to save, or mail them to me for safe keeping.  In the rigs that I converted to direct drive that is where I started. 

If they are like the typical Detroit iron, the hub that bolts to the drive just barely fits through the fan and ring that mounts the fan.  I welded the drive hub to the fan and installed a spacer with bolts replacing the studs in the drive (water pump) just like they were built before fan clutches.  In your case the fan ring would be used for a pattern to build an adapter. 

If you find the problem is the fan drives, and you get it working with the take out parts and want a set of direct drive hubs to fall back on, I could probably built you a couple hubs this winter.  I would need the whole fan/clutch assemblies and some additional info to do it properly.  Let me know.

 
Don 4107
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Don 4107 Eastern Washington
1975 MCI 5B
1966 GM PD 4107 for sale
1968 GMC Carpenter
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