Leak at rear transmission pan gasket

[wrongturninwv]

99 Subaru Outback SUS. 2.5 , auto trans. Rear of trans leaking at pan gasket. Was told at a shop that this is a common problem and he would not to use a new gasket but a sealer alone would stop the leak for ever.To me it would have to be a quick hardning sealer not to mix with the new trans fluid and cause me more problems..I have a new Fel-Pro gasket.but he says if I use it I would just have a leak again.Will also have him replace the filter when job is done. Just want to know what you guys think.Is he right or wrong. And if he uses the new gasket do you need a sealer on it, if so what kind would be best.  thanks all

[Rooster2]

If it were me, I would drop the pan, and clean off the old gasket from both the pan and tranny surfaces. Pieces will break off and stick to both surfaces. It takes some work to remove all traces of the old gasket, and it is a bear to remove all traces, as that old gasket really hardens onto metal surfaces. The cleaner all surfaces are, the better to move forward. If me, I would use the new Fel-Pro gasket and sealer. The sealer helps to stick to the gasket, and keep it in place, while the pan is being reinstalled. No need to replace the screen (not really a filter) inside the tranny. They don't seem to ever clog up.Best to replace the external ATF filter located off to the side near the bottom of the tranny. It looks just like an oil filter, but has a different media filter element inside the filter, compared to an oil filter. It spins on exactly like an oil filter.

Edited November 27, 2015 by Rooster2

[golucky66]

I recently did a tranny pan resealing on my tranny (2.2L impreza sedan) and let me just say that the trannys come from factory with a liquid gasket like RTV. I resealed my tranny using that and as long as you follow the direction, no problems will occur for another 100k+ miles. 

I personally have never used a true gasket on the trannys but some other guys at my shop that I work at dislike them because they say that it "doesn't hold up as well or seal as well" they could've did it wrong. I don't see why one would be better then the other provided you or they do it correctly. 

 

I agree with rooster2 on the "filter" there isn't really a "filter" on the transmissions until you get into the 2000's. Yours may have the external filter, my 96' impreza did not have an external. 

 

Best of luck.

[Rooster2]

I recently did a tranny pan resealing on my tranny (2.2L impreza sedan) and let me just say that the trannys come from factory with a liquid gasket like RTV. I resealed my tranny using that and as long as you follow the direction, no problems will occur for another 100k+ miles. 

I personally have never used a true gasket on the trannys but some other guys at my shop that I work at dislike them because they say that it "doesn't hold up as well or seal as well" they could've did it wrong. I don't see why one would be better then the other provided you or they do it correctly. 

 

I agree with rooster2 on the "filter" there isn't really a "filter" on the transmissions until you get into the 2000's. Yours may have the external filter, my 96' impreza did not have an external. 

 

Best of luck.

I have a 99 Leggie OBW, and it does have the external screw on tranny filter. So, pretty sure your car will have the external filter as well.

[idosubaru]

use RTV, no gasket.  those cork aftermarket gaskets suck and haven't been used for over a decade now by Subaru.

make sure the pan itself isn't too deformed - not flat or concave bolt holes from people trying to overtigthen the pan.

 

there's an internal screen "filter" - but it's hardly worth replacing except I guess if it comes with a new oring and you replace that while you're at it.  but the filter itself isn't even really a filter - they're just screens and don't clog.  if that's clogged or dirty you'll probably need a new transmission soon.

[Rooster2]

use RTV, no gasket.  those cork aftermarket gaskets suck and haven't been used for over a decade now by Subaru.

make sure the pan itself isn't too deformed - not flat or concave bolt holes from people trying to overtigthen the pan.

 

there's an internal screen "filter" - but it's hardly worth replacing except I guess if it comes with a new oring and you replace that while you're at it.  but the filter itself isn't even really a filter - they're just screens and don't clog.  if that's clogged or dirty you'll probably need a new transmission soon.

Learned something new. My last experience on a AT pan gasket came from working on a 91 Leggie that I had with a pan gasket. So, am glad to hear now about simply using RTV with no gasket in the much newer Subies.

[Fairtax4me]

Are you sure the leak is from the pan? If someone has ever had the tail housing off to repair the C duty solenoid the tailhousing could be leaking.

If it is the pan, make sure the pan bolts are snug. Sometimes with a gasket the pan bolts can loosen and it starts leaking.

 

 

Hard part about RTV is keeping trans fluid from running down and getting on the sealing flange of the trans while you're trying to get the pan positioned. I generally pull the pan and wait overnight for the trans to drain as much as it can to minimize fluid running out and getting in the way of the RTV.

 

Cork gaskets are useless. I avoid those like the plague.

 

There are rubber material gaskets that work fairly well as long as you don't overtorque them, and they're fairly forgiving of small drips/runs of fluid running down onto the gasket surface from inside the trans.

 

Would be nice if someone made a re-usable rubber/silicone coated metal gasket for these, but I haven't found one yet.