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Topic: Strange Tranny Leak (Read 604 times) previous topic - next topic

Strange Tranny Leak

A year ago or so I had the transmission flushed, new filters installed, and new TranSynd fluid added.  Since the service we've put less than 1000 miles on the couch until an extended trip to the Canadian maritimes this spring

No issues from Florida, after several overnights, before we hit New York State. After leaving a Campground in upper New York State, we had a series of hills to traverse and the retarder got a lot of use on the downhill sections. Then, we had a particularly bumpy interstate route through New York, west of New York City, and New Jersey, and at a rest stop my typical walk around showed fluid across the front of the jeep. It wasn't oil, and I suspected transmission fluid. A quick look under the coach confirmed some fluid loss from the tranny buy a wet section on the bottom of the transmission pan.

Prior to our stop for the night the transmission diagnostic panel continue to show no fluid deficit. Looking under the coach after we stopped, it appeared that fluid was present only on the passenger side of the bottom transmission pan, particularly around the secondary filter  Port. I cleaned the transmission and for the next couple of days while we were stopped, there were no subsequent drips.

Today we ran several hundred miles at interstate speeds, and during our periodic breaks I checked and there was no fluid loss. When we arrived at our destination today, there was no additional spray across the front of the jeep, and the diagnostic panel continues to show the transmission is full.

 I will eventually have an Allison dealer check the transmission and I suspect that it's possible a O-ring or gasket around that secondary filter may have been compromised somewhere along the way. But, I'm particularly curious why I would have a fluid loss during a particular portion of the  Journey, but no subsequent loss. And, no indication of the diagnostic panel of a fluid deficit.

Ideas are welcome. I'll report the conclusion once I've met with the Allison dealer in Maine, but I am perplexed.
Randy (N4TDT) and Karen Crete
Sarasota, Florida
SOLD:  2000 U270 34' WTFE Build 5756 "Ole Red"

Re: Strange Tranny Leak

Reply #1 –
Randy, do you have a VMS pc? If so what were the temps going downhill? 230 on the factory trans temp gauge is probably near 300 at the retarder. If the fluid got really hot it could have expanded.
1999 40 ft. U-320 wtfe build 5563 Chuck & Lynda's "Rollin' Inn"  2030 watts solar
prev. mh's 71 GMC 5 yrs. 73 Pace Setter 1 yr. 78 Vogue 5 yrs 81 FTX 40ft all electric 18 yrs. 1996 Monaco Signature 3 yrs.
2014 Grand Cherokee Overland
Dream as if you will live forever. Live as if you will die today.  James Dean

Re: Strange Tranny Leak

Reply #2 –
Yes, Vmspc did show higher temps but not as high as our west a couple of years ago. No spray then but I wondered if this was possible. Where would it leak from if expanded?
Randy (N4TDT) and Karen Crete
Sarasota, Florida
SOLD:  2000 U270 34' WTFE Build 5756 "Ole Red"

Re: Strange Tranny Leak

Reply #3 –
I don't know where the vent is on your transmission but, that would be my guess where the expanded fluid would exit.
1999 40 ft. U-320 wtfe build 5563 Chuck & Lynda's "Rollin' Inn"  2030 watts solar
prev. mh's 71 GMC 5 yrs. 73 Pace Setter 1 yr. 78 Vogue 5 yrs 81 FTX 40ft all electric 18 yrs. 1996 Monaco Signature 3 yrs.
2014 Grand Cherokee Overland
Dream as if you will live forever. Live as if you will die today.  James Dean

Re: Strange Tranny Leak

Reply #4 –
Wonder if the transmission was over-filled at the last service.

What does fluid level show when you check using the Allison shift pad:

Trans completely up to temp-- 50+ highway miles.

Engine running, transmission in Neutral.

Hit the up and down arrows at the same time.

That will bring up OL and begin a countdown and then either plus or minus the number of quarts.

Let us know what you find.

BTW, Allison does not recommend flushing the transmission, just changing fluid and filters.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Strange Tranny Leak

Reply #5 –
Quote from: wolfe10 –
Wonder if the transmission was over-filled at the last service.

I was wondering as well, since there are both a 4" and a 6" sump available for the transmission....  If done by a shop, they should have checked the data tag on the transmission.

@floridarandy - do you have a record of how much transmission fluid was used?
Learn every day, but especially from the experiences of others. It's cheaper!  - John C. Bogle

2000 U320 36' non-slide / WildEBeest Rescue
2003 U320

Re: Strange Tranny Leak

Reply #6 –
Randy just serviced mine, took 1 5 gallon bucket and 2 quarts. Shift pad check says ok.
Bruce, Linda, and Macy
Zoey RIP 1/20/19
1999 U295 40' build #5400
2017 silver Jeep Wrangler, 1260 watts of solar on top
Moving around the country

Re: Strange Tranny Leak

Reply #7 –
Paul Yasbeck did service so I trust correct amount was used.  My term was "flush" not his. Diagnostics show OL OK after yesterday trip of 70 miles.
Randy (N4TDT) and Karen Crete
Sarasota, Florida
SOLD:  2000 U270 34' WTFE Build 5756 "Ole Red"

Re: Strange Tranny Leak

Reply #8 –
It doesn't appear the fill tube is the source of the leak.
Randy (N4TDT) and Karen Crete
Sarasota, Florida
SOLD:  2000 U270 34' WTFE Build 5756 "Ole Red"

Re: Strange Tranny Leak

Reply #9 –
It would be the vent tube that would spit excess fluid. It is lower than the fill tube.
1999 40 ft. U-320 wtfe build 5563 Chuck & Lynda's "Rollin' Inn"  2030 watts solar
prev. mh's 71 GMC 5 yrs. 73 Pace Setter 1 yr. 78 Vogue 5 yrs 81 FTX 40ft all electric 18 yrs. 1996 Monaco Signature 3 yrs.
2014 Grand Cherokee Overland
Dream as if you will live forever. Live as if you will die today.  James Dean

Re: Strange Tranny Leak

Reply #10 –
Where is the vent tube. Same side as fill?
Randy (N4TDT) and Karen Crete
Sarasota, Florida
SOLD:  2000 U270 34' WTFE Build 5756 "Ole Red"

Re: Strange Tranny Leak

Reply #11 –
It is also called a breather.

RV Tech Library - Allison Transmissions
1999 40 ft. U-320 wtfe build 5563 Chuck & Lynda's "Rollin' Inn"  2030 watts solar
prev. mh's 71 GMC 5 yrs. 73 Pace Setter 1 yr. 78 Vogue 5 yrs 81 FTX 40ft all electric 18 yrs. 1996 Monaco Signature 3 yrs.
2014 Grand Cherokee Overland
Dream as if you will live forever. Live as if you will die today.  James Dean
 

Re: Strange Tranny Leak

Reply #12 –
Well, I think we have a resolution and a winner.

Arrived Portland, Maine with an appointment at Power Products, an Allison dealer.  Tranny had been clean of leaks last two legs of our trip after the initial leak.  No leaks and all tranny pan and filter bolts were snug. Steam cleaned to make certain any future leaks would be easy to spot.  Ran diagnostics on Tranny and all showed clutches showed good.  Fluid was not overfilled.  Quick fluid sample test showed no glycol.  Old time Allison mechanic said these trannys are bulletproof and fail, in his experience, only when fluid has become contaminated.  We have had a fresh Transynd fill and new filters at last service.

So the winner is Craneman.  Shop tech agreed that retarder use and related heat and pressure could result in a discharge from the breather tube.  Otherwise they could find nothing else out of order and, while they can't guarantee there isn't a future issue they couldn't recommend any further intervention.
So its off to the Maritimes without reservation.  Should there be any further updates I'll update the post.

Thanks to all.

Randy (N4TDT) and Karen Crete
Sarasota, Florida
SOLD:  2000 U270 34' WTFE Build 5756 "Ole Red"