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oil comes out the trans filler tube

 
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CEO77 CEO77
New User | Posts: 4 | Joined: 10/10
Posted: 10/31/10
05:13 AM

my car is a 77 Trans Am with a TH400 I rebuilt mabey 15 years ago that now has oil leaking out the top of the dip stick tube. It seems to only happen  when its at wide open. I lowered the trans off the crossmember just to check if the vent tube was dameged or plugged, blew air into filler tube with smooth air flow out vent tube. Oil level is not over full, its on the add one pt. mark now. It looks as if very little if any oil has ever come out the vent but it sure is a mess by the filler tube top. Why would oil rather come out the filler tube than the vent?  

waynep7122 waynep7122
Addict | Posts: 4561 | Joined: 08/09
Posted: 10/31/10
06:48 AM

just curious...    do you have a restricted oil cooler tube????

any oil cooler lines that were twisted when somebody worked on the radiator...  or smashed under the motor mounts...  

Stuart Stuart
User | Posts: 164 | Joined: 04/06
Posted: 10/31/10
07:16 AM

It may have worn metal rings on the stator support and allowing pressure to blow past them.  
Journeyman mechanic, transmission builder since 1963.

CEO77 CEO77
New User | Posts: 4 | Joined: 10/10
Posted: 10/31/10
09:57 AM

I have looked at the cooler lines while cleaning them off, and they look OK. If I was to check for a restricted flow, how might I do this. How much line pressure might be in these lines. Would it be reasonable to take the return line off at the tran, add a hose long enough to make it to a bucket and start it up. Ive never done this before and am not sure what to expect. The last time the car was driven was before this, motor was R&R for a small problem. that went smooth,nothing broke or was damaged that I know of. I hoping its not worn rings and feel that the motor R&R might have something to do with it, everything worked good before. How might the cooler lines being kinked or restricted push oil up the filler tupe and not the vent.    It would be masking the problem   but any opinions on the locking dip stick tubes I found on the web.  

Stuart Stuart
User | Posts: 164 | Joined: 04/06
Posted: 11/01/10
01:13 PM

As you mentioned a locking stick is masking the problem.

Like squeezing your cheeks to hold in a fart.

Sooner or later it's gonna fart. Tongue  
Journeyman mechanic, transmission builder since 1963.

waynep7122 waynep7122
Addict | Posts: 4561 | Joined: 08/09
Posted: 11/01/10
01:54 PM

i am going to agree with stuart...   its probably an internal leak...

i am not that good at transmissions... i keep my head under the hoods... working on the noise makers..

when the cooler lines get kinked the transmission can overheat and cause the fluid to bubble and erupt from the filler tube..

when the sealing rings fail...  the fluid can be sprayed into areas and foam to blow out the fluid from the dip stick..

i would also think that there might be a converter fill problem...    so when the engine is operated at high speed.. the fluid is allowed to escape into the case.. this will cause the fluid level to rise in the case and overflow the dipstick..

if the bushings in the transmission are worn.. the harmonic vibrations can cause the sealing rings to leak...

one of my first jobs was working at a transmission shop.   doing R&R...   i could slide 10 feet on layer of ATF on the floor..  when i took off my work boots.. my feet were red with the ATF...  it was not a great place to work.. but it was only my second job from high school...  i still hate the feel of ATF on my arms...  

CEO77 CEO77
New User | Posts: 4 | Joined: 10/10
Posted: 11/09/10
04:14 PM

I did another test drive today and all is well now. I believe that the add one qt. mark might not be as it seams.After dropping the pan I could see that the valve body bolts were just touching the oil level at the add mark. While draining I measured 4 qts out. When I put 4 qts back in it just made the bottom of the stick. It took another two full qts to reach the full mark, mabey, just above it now. I nailed it twice on the drive and there was no oil smoke coming from under the hood. It had to be cavitation and so much sudden case pressure the little vent couldn't deal with it. Thank You so much for your help during my IQ test.  

Stuart Stuart
User | Posts: 164 | Joined: 04/06
Posted: 11/10/10
07:58 AM

The full running mark is even with the pan/case connection.
Run the stick along the outside of the tube and check the mark.  
Journeyman mechanic, transmission builder since 1963.

CEO77 CEO77
New User | Posts: 4 | Joined: 10/10
Posted: 11/10/10
06:04 PM

I was able to see that from under the trans with the pan off.   It is as you say, oil would be equal to the full mark and the top of the pan. When it was at the (Add one Pint) mark it was Just equal to the valve body bolts. With my lower IQ Im not going to question why I needed two more qts to hit the full mark. One other item that might have been a factor was the temperature of the trans oil. At the track I always had things warmed up for consistency unlike the short drive around town. Mabey thats how I got away with it for so long.         Time will tell.  

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