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Topic: Oil Leak on left side of Alison Transmission 1997 U270 6 speed Allison (Read 985 times) previous topic - next topic

Oil Leak on left side of Alison Transmission 1997 U270 6 speed Allison

Today I noticed a foot long streak of oil (assuming it is ATF) under the coach in my parking spot....apparently leaking from the left side of the trans well forward of the bell housing.  The bottom of the trans looks pretty oil soaked as well.  This has happened after a week trip that ended 2 days ago with no previous history of leaks in the 2 months of coach ownership.  I lifted the bed and the leaking area seems to be near the lower part of the middle of the trans...perhaps a loose pan gasket or maybe there is an overflow or fitting there?  I will move the coach and have a closer look tomorrow and I put a drip pan under to see if more is leaking.  Everything seems normal otherwise and fluid levels were fine last time I checked with the dipstick...and at this rate it might take along while but with a cross country trip later this month want to know what I should look for once I am under there with a light and degreaser.    I think the fluid was changed by the previous owner who was pretty meticulous but don't know what type is in the trans now...any way to tell by color or ? in case I need to add more.
Coach is a 1997 U270 with the 8.3 and 6 speed Allison push button trans. Any advice appreciated.
Carl and Kathleen
Killeen Texas
1997 U270

Re: Oil Leak on left side of Alison Transmission 1997 U270 6 speed Allison

Reply #1 –
I had a leak like that. The coach was parked in a storage shed with a gravel floor. I thought it was transmission fluid. But, the transmission was always full when I checked it. I moved to a shed with a concrete floor. I then saw the puddle of fluid. Turns out it was the fuel lift pump that was leaking. It only leaked when the engine was started and when the engine was turned off. Never leaked when running. It seems that the use of biodiesel fuel caused the seals in the pump to leak.
Larry
Larry and Terry
Ex 2004 U270 36'

Re: Oil Leak on left side of Alison Transmission 1997 U270 6 speed Allison

Reply #2 –
check output seal, can be damaged if coach moved when raised up - not too many $$ to fix if that id the issue

Careful - do not get under coach without safety stands (8) - four on each corner
Tim Fiedler    2025 LTV Unity MBL on Order
2000 Chevy Tracker 2 Door Convertible 4WD Now lifted 4.5"
1985 Citroen 2CV6 Charleston
Murphy Rebel on wheels with 175HP Titan
Cessna P337
1980 48' Westport MY (!/4 Share)

Re: Oil Leak on left side of Alison Transmission 1997 U270 6 speed Allison

Reply #3 –
Verify what the fluid is.When you check the lift pump make sure the fuel filter above it is tight.Instead of degreaser try brake
cleaner it dries faster.
96 U270 BUILD 4810
85 380SL
Drummonds TN.

Re: Oil Leak on left side of Alison Transmission 1997 U270 6 speed Allison

Reply #4 –
Your transmission has two dipstick ports. The driver side is typically plugged in our coaches. Being made of rubber they can shrink over time. I would check and make sure it is tight. Our last coach was leaking there. The screw should have some adjustment to expand a little more , if not it's a fairly common piece . Napa would be a good place to start if it is the problem.
Tom
1998 U320 40'

Re: Oil Leak on left side of Alison Transmission 1997 U270 6 speed Allison

Reply #5 –
Quote from: TAS69 –
Your transmission has two dipstick ports. The driver side is typically plugged in our coaches. Being made of rubber they can shrink over time. I would check and make sure it is tight. Our last coach was leaking there. The screw should have some adjustment to expand a little more , if not it's a fairly common piece . Napa would be a good place to start if it is the problem.

Yup, the very first thing to check. Could be either side: the "blind plug" side or the gasket/grommet around the dip stick tube.

Sure, it could be something else, but start with the easy/inexpensive ones.
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: Oil Leak on left side of Alison Transmission 1997 U270 6 speed Allison

Reply #6 –
To add to the plug mentioned, if when tightening that nut it does not stop you will have to drain some Tranny fluid out then remove the rubber plug. You can fix it by taking out the centre metal piece of pipe spacer and grinding it down a bit shorter, This allows the nut to be tightened further than before so it expands the plug. I had to do this on the 240 and that stopped the oil loss. Simple job but if this is the cause first clean the Tran' casing well before draining oil so you can reuse the oil. I also ran it thru a cloth filter- just in case.
JohnH
Coachless, now use aircraft. 2003 Ford Travelair TC280 class C. Super shape. Just for 1 yr .
1994 Ford E350 ClassC,total renovation inside and out. Now sold.
2000 U295  36' Cummins 350 c/w Banks Stinger, Resonator upgrade,Solar, LED lites.Residential fridge with slide out pantry. Build 5674. Sold
ex 92 GV 022C ored Cummins. Sold
ex 95 GV240 cat 3116. Sold
2017 Mini cooper s & 2016 land Rover LR2 HSE  LUX.
jhaygarth@aol.com    SKP #130098
treat everyone as you would like to be.

Re: Oil Leak on left side of Alison Transmission 1997 U270 6 speed Allison

Reply #7 –
If you are going to repair the leak, go to Allison and get the updated plug, do it once and do it the correct way.
The selected media item is not currently available.Bill&Doris 97 U270 36'
University of Parris Island Class of 66
Semper Fi  Build# 5174 MC#17094

Re: Oil Leak on left side of Alison Transmission 1997 U270 6 speed Allison

Reply #8 –
Happy ending here.  Cleanup with 2 cans of brake fluid and degreaser revealed the drivers side dipstick hole cap was weeping ATF.  The local Allison dealer sold me the new plug which is a simple tap in grommet and yellow plastic center piece for $26.50.  Tapped in and done.  Does not seem like it will leak.  The old plug is no longer available and there is a Allison bulletin on the new plug.  I don't know why the old plug suddenly started to leak after 18 years but there was not enough adjustment in the bolt to seal it and it was loose to the touch.  Finally...thanks for the great advice of changing the plug with the engine running...worked fine and no more ATF was lost. 
Carl and Kathleen
Killeen Texas
1997 U270

Re: Oil Leak on left side of Alison Transmission 1997 U270 6 speed Allison

Reply #9 –
Quote from: Carl Cox –
Finally...thanks for the great advice of changing the plug with the engine running...worked fine and no more ATF was lost. 

What advice was that ?
Dave W. (AKA Toyman )
'03, 270, 36', Build 6095, Pulling whatever I hook it to.

"Don't cry because it's over. Smile because it happened."
Dr Seuss

Re: Oil Leak on left side of Alison Transmission 1997 U270 6 speed Allison

Reply #10 –
Quote from: toyman –
What advice was that ?
By having the engine running the trans sump is empty...and so when you pull the plug out you don't lose 2 gallons of expensive messy ATF.  Good trick and new plug goes in quick.  This should be the first place to look if you develop a ATF leak and easy to fix.
Carl and Kathleen
Killeen Texas
1997 U270

Re: Oil Leak on left side of Alison Transmission 1997 U270 6 speed Allison

Reply #11 –
Quote from: Carl Cox –
By having the engine running the trans sump is empty...and so when you pull the plug out you don't lose 2 gallons of expensive messy ATF.  Good trick and new plug goes in quick.  This should be the first place to look if you develop a ATF leak and easy to fix.
I hope you mean the level is below the plug as the sump should not be empty.
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: Oil Leak on left side of Alison Transmission 1997 U270 6 speed Allison

Reply #12 –
Quote from: craneman –
I hope you mean the level is below the plug as the sump should not be empty.
Probably.....guess there must be oil in the sump even when running....but most is pumping around and below the level of the plug...so none came our when I pulled the leaking original plug.
Carl and Kathleen
Killeen Texas
1997 U270