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Author Topic: Power Steering problem could have caused engine failure!  (Read 3078 times)
rv_safetyman
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Jim Shepherd


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« on: December 07, 2007, 06:15:27 AM »

Sean Welsh posted a compelling story on his blog (http://ourodyssey.blogspot.com/).  He is currently on assignment with the Red Cross in Portland and will not be able to post the story on this board for a while.  However, I was very startled about the facts of the problem and the fact that it could have easily caused an engine failure.  I hope he won't mind my posting a synopsis of the problem.  Since it could affect a lot of us, I thought it was important to get the information out as soon as possible.

Briefly, he noted a significant loss of PS fluid (PS quit working) and filled the reservoir several times.  He could not find the leak.  A reader of his blog suggested he check his engine oil.  It was way over full and very thin from ATF fluid.  The pump seal had apparently gone bad and leaked fluid into the engine.  I fancy myself as a pretty savvy mechanic and a half way decent engineer and I would have never thought about this type of failure.

If he had been driving on a hot day up a steep, long climb, he probably would have lost his engine.

You can find a few more details on his blog (good reading in any case).

Jim

« Last Edit: December 07, 2007, 06:18:03 AM by rv_safetyman » Logged

Jim Shepherd
Evergreen, CO
85 Eagle 10/Series 60/Eaton AutoShift 10 speed transmission
Somewhere between a tin tent and a finished product
Bus Project details: http://beltguy.com/Bus_Project/busproject.htm
Blog:  http://rvsafetyman.blogspot.com/
Brian Diehl
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« Reply #1 on: December 07, 2007, 06:27:57 AM »

That is scarry Jim!  Thanks for sharing.  I wonder why he is using ATF?  I know MCI called for straight 40w in the 96A3 power steering system.
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Catskinner!
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« Reply #2 on: December 07, 2007, 06:29:26 AM »

That is the reason I use the same oil in my power steering
that I run in the engine.  

When I bought my pump and steering sector from Power
Steer, I ask what oil I should use and they told me the
best and safest was to use the same engine oil for this
reason.

The only drawback is when it is cold it takes a few minuets
for it to flow properly.

Catskinner!
Sonnie Gray
72 0/5 Eagle 3406 Cat
Pottsboro, Texas
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rv_safetyman
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Jim Shepherd


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« Reply #3 on: December 07, 2007, 07:15:48 AM »

I went to my Eagle Maintenance manual and it confirmed what I thought I recalled - recommended Dextron II. 

Based on this issue, I guess I will change over to my engine oil.  I don't think it is a huge issue with my system as the reservoir is not too big, and the Series 60 holds 11 gals.  However, it is better to be safe than sorry.

I assume that draining the reservoir and filling with engine oil will be a start and that it should be done a couple of times to get the mixture of ATF and engine oil out of the system.  They do mix OK don't they?

Jim
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Jim Shepherd
Evergreen, CO
85 Eagle 10/Series 60/Eaton AutoShift 10 speed transmission
Somewhere between a tin tent and a finished product
Bus Project details: http://beltguy.com/Bus_Project/busproject.htm
Blog:  http://rvsafetyman.blogspot.com/
makemineatwostroke
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« Reply #4 on: December 07, 2007, 07:31:56 AM »

Jim, if you have the Eaton pump that Eagle installed it has a safety hole in the bottom ( a soft plug) to prevent oil going into the crankcase if the seal fails this is why it calls for ATF the fuel pumps on 2 strokes have the same feature.And if you do have the Eaton B pump i would not change to engine oil  but a Vickers pump is ok with it
« Last Edit: December 07, 2007, 07:49:23 AM by makemineatwostroke » Logged
Lee Bradley
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« Reply #5 on: December 07, 2007, 08:11:11 AM »

My Neoplan runs ATF in the power steering and looking at the steering unit I think I will continue to use ATF. Even if the PS reservoir dumps all 6 quarts in the engine, it should not hurt it as long as you start investigating why your PS is not working and don't just keep adding ATF.

I am sure that most of the PS pumps have a bleed hole but when was the last time you checked to make sure it was clear?

Sean's Odyssey had a PS hose failure a few months back and ran out of ATF several times if my memory isn't too faulty. I suspect that may have contributed to the pump seal failure.
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rv_safetyman
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« Reply #6 on: December 07, 2007, 08:13:09 AM »

I am not sure what pump the Series 60 has on it.  We are away from the bus right now.  I will have to check it out when we get back.

Sean has an 8V92 in a Neoplan.  I think it was a conversion, so no telling what the pump is.  Must not have had a safety hole.

Jim
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Jim Shepherd
Evergreen, CO
85 Eagle 10/Series 60/Eaton AutoShift 10 speed transmission
Somewhere between a tin tent and a finished product
Bus Project details: http://beltguy.com/Bus_Project/busproject.htm
Blog:  http://rvsafetyman.blogspot.com/
TomC
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« Reply #7 on: December 07, 2007, 09:00:14 AM »

I know with the Sheppard box I have, I was told to use 15W-40.  Hopefully Sean caught it in time since he just had the whole engine rebuilt.  Good Luck, TomC
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« Reply #8 on: December 07, 2007, 07:33:39 PM »

My MCI-9 Manual (1989) calls for 10W-40W .   One more thing to change.

Bill
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Sean
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« Reply #9 on: December 08, 2007, 09:34:28 PM »

Well, I have a few minutes to catch my breath here, so I will try to answer the questions that have come up on this thread.

First off, thanks, Jim, for posting this.  I was caught completely off-guard by this, and your post here may save someone else's bacon.  It was only through good fortune and/or timing that three knowledgeable people happened to read my blog post that night, and sent me emails before we left in the morning.

Brian Diehl wrote: "I wonder why he is using ATF?"

The answer is: Because that was what was in the system when I got the bus.  I don't have any documentation or specs on the system, so I have no idea what the allowed or required fluids are -- I just continued using what was already there.

My system, by the way, is bastardized -- the steering box is original equipment on the bus, and is probably a Mercedes part.  The bus was built in Pilsting, Germany, and the hubs and axles are all Mercedes.  None of the front-end steering gear has ever been replaced, so it is 22 years old.

The engine, on the other hand, was replaced here in the US when the bus was only a couple years old.  It likely had either a Mercedes or Deutz engine in it when it was built, and Neoplan USA swapped it out for a brand new 8V92TA Detroit.  The gearbox was replaced at the same time  -- again, OEM was likely either ZF or Mercedes, and was almost certainly manual, and it was replaced with an Allison HTB748.  The pumpkin, however, is OEM Mercedes.  The mate-up looks to have been a torch-and-weld job.  In any case, the power steering pump must have been changed with the engine, from a (probably) belt-driven one off the Deutz or Mercedes to a gear-driven unit on the Detroit.  I'm almost certain the pumps are not interchangeable between these applications.

"makemineatwostroke" wrote about the differences between Eaton and Vickers pumps.  I don't know which I have -- without getting the bus on a lift or over a pit, it's nearly impossible to get to, so I can't look.  I am guessing Vickers, because those are, apparently, the ones with the tendency to drain back into the engine sump when the shaft seal goes.  At least, according to the gentlemen who saved my butt by writing in to warn me about this.  And while the Vickers may be fine on motor oil, it's not clear that the steering box will be.

Lee Bradley wrote that I had a hydraulic hose rupture on my steering system a while back, and this is true.  We never lost enough fluid, though, to even drop below the sight glass.  That said, replacing the hose introduced a large air bubble into the system, which took quite a while to work all the way out.  The steering would "quit" on me at random times, usually while trying to parallel park.  I suspect the air in the system contributed to the failure of the 19-year-old pump seal.

TomC wrote that his Sheppard steering uses 15W-40.  And I will tell you that what I did, to safely continue the rest of the way (700 miles) to Portland from central California (disaster victims can't wait), was to simply start adding 15W-40 to the steering reservoir instead of ATF.  I also had the engine oil changed at the very next express lube shop we passed, also to 15W-40 (none of these places stocks 40-weight any longer, and the multi-grade was certainly better than the 30% mix of ATF I had in the crankcase, and fine for the 700 miles it was going to be in there).

After running the 700 miles to Portland this way, I can report that my power steering is NOT designed to run on 15W-40.  It sounds like a rutting moose when the engine is first started, and much worse when the weather is cold (it's 35 here tonight -- and we were in Palm Springs, where it was 80, when they called us).  It also shudders a bit at low speed maneuvering, especially when cold.  That said, I'm pretty sure the 15W-40 is not doing any actual damage.  I'll switch back to ATF, or maybe try straight 30-weight, when I get the pump repaired.  By the way, I have no idea how much fluid my steering holds in total, but the reservoir alone is well over two gallons.  When the steering "quits" due to low fluid, it takes around two and a half gallons to fill the reservoir.  After starting the engine and making a couple left/right wheel cranks, there will be room for another half gallon.  So maybe twice as big as Lee's "six quart" system.

Only time will tell if we thinned the oil enough to do engine damage.  I will need to flush the oil system, refill with 40-weight, and run a few thousand miles before I can pull a meaningful oil sample.  And, yes, for the record, we have less than 10,000 miles on a complete in-frame rebuild right now.  I have my fingers crossed that we did only minimal damage to the bearings, rings, and liners.  On the bright side, the oil passages are very, very clean now.

-Sean
http://OurOdyssey.BlogSpot.com
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Full-timing in a 1985 Neoplan Spaceliner since 2004.
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scanzel
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« Reply #10 on: December 10, 2007, 08:42:52 AM »

Sean you say that your power steering sounds like a rutting Moose when cold and then clears up when warm. When I bought my bus in 2005, while bringing it back from Reno to Connecticut we blew the power steering pump in Wyoming and drove back with no power steering. When i had the pump replaced they put 15w40 in saying that this is what is used now in the newer buses. I still get the loud noise when starting up in cold weather then it clears up. Sounds like maybe i should drain the system and go back to Dextron. I think motor oil is just too thick when cold. Then noise i get seems to come from under the floor area but is very had to isolate unless you can get under the bus when cold. Has anyone removed their gear driven pump and gone to a belt driven one?
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Steve Canzellarini
Berlin, CT
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Sean
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« Reply #11 on: January 05, 2008, 09:40:21 PM »

Well, we have finally resolved this problem, and I thought I would report back here on the results.  (The long delay had to do with the fact that we spent three weeks dealing with the flood relief operation here, after which we ran smack dab into the holidays, when getting into a shop is a challenge.)

And (drumroll please), here is what we think happened:

For whatever reason, probably just age, the fiber drive "gear" (really just a disk with four notches for a pair of dogs on the camshaft to mate with a pair of dogs on the steering pump)

completely disintegrated.

This is what was left of the gear, as retrieved from the oil pan:


Once the gear was gone, the dogs on the camshaft basically beat the heck out of the dogs on the steering pump, with the inevitable result being the failure of the shaft seal.

As you now know, we blew a bunch of ATF into the crankcase before we figured out that's where it was going, which thinned the 40-weight down to the consistency of gasoline.

The net result was that, between the debris from the gear itself, and the lack of lubricating viscosity, we toasted the bearings (which, I might add, were less than 10,000 miles old) in less than a thousand miles:


We now have a brand new Eaton/Vickers steering pump (ordered from MCI), a fresh set of 26 bearings, and fresh Delo-100 40-weight oil and things are mostly back to normal (well, my wallet is lighter).  We are counting ourselves lucky not to have completely grenaded our freshly-rebuilt engine.

More detail on the pump replacement, complete with photos, is here:
http://ourodyssey.blogspot.com/2008/01/our-moose-is-gone.html

More detail on the bearing replacement and discovery of the gear debris, also with photos, is here:
http://ourodyssey.blogspot.com/2008/01/hunkering-down.html

On the blog, you can click on the photos for full size versions (the ones here in this post are very much reduced).

It's (IMHO, of course) a good read, and I hope it will save someone else from the same fate.

-Sean
http://OurOdyssey.BlogSpot.com
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Lin
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« Reply #12 on: January 05, 2008, 10:20:02 PM »

My MC-5a manual calls for 10w motor oil or Type A-Suffix A ATF.  This ATF was apparently superceded by Dextron.
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« Reply #13 on: January 08, 2008, 09:29:52 PM »

Lin,

I have a '52 GMC M135 6x6 military 2 1/2 ton truck with a HydraMatic trans. This trans was originally supposed to use 10W motor oil as per the Army manual but all owners I know have switched to Dextron because the motor oil foams too much and is impossible to find anyway.

From what I can find out the Army usede 10W in an attempt to standardize since nothing else in the Army used ATs. This trans is straight out of a '51 Cadillac auto except for a two speed aux bolted onto the rear. I think the Army later changed the manual to state Dextron but can't document that.

This is a great truck by the way!!
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