TRANSMISSION CAP LEAKING
 

The usual transmission leak after sitting a few days the owner has replaced the cap. I have had it sitting for 4 days and no leak but fluid level is below max line due to previous leaking before I received the car.
I used a pressure tank and added fluid to exceed the full mark and now it is leaking from the cap.
Short of replacing the tank has anyone come up with a method to seal this such as, teflon tape or silicon sealant. I am sure the tank lip is compromised and would like to find a work around.

Why not just fix it correctly, instead of figuring out a patch?

It's not like the tank is big money.

Maybe you just need a gasket for the cap.
Also, fill it when the car is running (park).

Yes your correct it should be replaced the car is in pieces for a TB water pump replacement. This is temporary fix to stop fluid in his driveway until we get time to change it in a couple of weeks. I need to get it off of my lift this weekend and part was not ordered in time.

I wouldnt be surprised if you could match one up from the local parts store (the rubber cap gasket).

Get/make a cap gasket and check that the overflow tube is snug and not split.

Overflow is hose Is fine New cap equals new gasket maybe a little more pliable gasket is in order.

Another possible source of a leak :

The 'elbow' from the oil pan slips an oring that is retained to the side of the fluid tank by a screw on hollow fitting. If you drain the pan and remove that 'tank', you can replace that oring (I doubled up on them). Then I slip fit it all back to gether, and after I lightly installed the tank screws (that hold the stone guard on) I screwed the fitting down.

My leak came from this fitting on the elbow. Someone told me they are often cracked either by people dropping the X-member before removing the reservoir or over-tightening the fitting.

You may want to get a replacement o-ring for that also and replace it all (a good time to do a filter service).

Hmmm, that should take care of that area. Other leak sources - the elbow dcrasta mentions and the Bowden cable fitting both have o-rings. The B2-piston cover has an o-ring. The latter two are over the reservoir and might give the appearance of a reservoir leak. But they leak when the car is running, not sitting.

I can see it leaking out of the cap threads but will check the other areas.

Paul mentioned a possibility of a check valve used in the lines where is this located?

There is a check ball located in the return line fitting on passengers side of trans. On all automatic transmissions, fluid is checked when running. If there were no check valve in the return line, fluid level would rise and leak when not running.

It is true that this is the likeliest leak spot if it puddles when not running. And you have evidence the seal is not working despite being new. The gasket is key. It would be worth taking a close look at it. The cap does need to be snug. I give it a very slight turn beyond hand tight with a 17mm wrench.

Where is this?

There's a check valve on the filler extention, on the passanger side, to keep fluid from running out the tube when you remove the "sealing" nut but I've never seen one in any return line....

Layer of Drei Bond on the threads of the cap.

Stuff is amazing.