Tranny leak!!! What's the first thing....

K. Roman · K. Roman's Garage

Tranny leak!!! What's the first thing I should do? I was just about to change the fluid to Swepco, don't really know what was in it before. There are green/blue drops coming from the area around where the plugs are. Haven't lifted the car yet to check it out, but am concerned.

Anyone know what I should do?

MichiganMat · MichiganMat's Garage

1st: find out where the leak is coming from.

Check the output shaft seals. They can go and fluid will leak all over the place. When you fill the tranny with new swepco, be sure to only fill until about 1/2 inch below the fill plug or the seals will fail.

SpeedracerIndy · 09-18-2004, 09:47 PM

Quote:

Originally posted by MichiganMat
When you fill the tranny with new swepco, be sure to only fill until about 1/2 inch below the fill plug or the seals will fail.

Why is that? I thought you were supposed to fill it to just below the fill plug.

K. Roman · K. Roman's Garage

Arrggghh! I'll check where leak is coming from tomorrow morning.

But, still will need some assistance! :O

Jim Sims · 09-19-2004, 03:14 AM

With the car level, fill the transmission with the correct oil until it begins flowing out the filler hole; failure to do this can leave it low on oil. DO NOT FILL A HALF INCH BELOW. Running this way (low on oil) will result in wear to fifth gear and it's assocated parts. The transmission has a vent and if open and correctly installed this will prevent any internal pressurization and possible seal leakage. Remember before opening the drain plug ensure you can open the fill plug. Are the leaks reaching the ground? Jim

djmcmath · 09-19-2004, 07:56 AM

Slightly aside -- without looking close, any tranny oil leak is liable to look like it's coming from the drain plug, as that is the low point. Oil leaking from a nearby case joint will dribble towards the plug and drip off at the plug.

Next thought -- switching to Swepco won't make anything stop leaking. Also, Swepco is blue/green in color -- sounds like you're already using it.

If you're lucky, it really is just the plug leaking. Use a wrap or two (but never more than two) of teflon tape, available at your local plumbing supply place (or hardware store, or sometimes even auto parts store).

Dan

makaio · 09-19-2004, 08:26 AM

K. Roman, it's hopefully something quite simple like a loose drain plug. To bad you're not at your dads house, I would have you just stop by and we could try and sort it.

MichiganMat · MichiganMat's Garage

hrm, thats strange. I saw someplace on the list here that filling to the top of the fill plug was bad for the seals.{shrug}. Sorry for the misinformation.

K. Roman · K. Roman's Garage

Thanks for the replies, and thanks for the offer makaio, I did look under it after I jacked it up. It seems the freshest green oil is in drops on a plate with four screws at the bottom of the tranny. The plugs look fine. I looked above the plate to see if it was leaking from above this plate but could not detect any oil. Could there be a gasket under the plate that needs replacing?

TIA

SpeedracerIndy · 09-19-2004, 11:42 AM

There is a gasket under that plate, and from my experience it seems to be a pretty common place for a leak to start. The plate is where the shift fork guide fork is mounted, and it is a good time to check the mounting bolts for the guide fork to see that they are all tight. When I did my rebuild I found my guide fork flopping around on that plate causing most of my shifting problems. You will have to drain the fluid before removing the plate. Do a search on gasket material here and research the different kinds of gaskets available. I ended up using a silicone based high temp material to finally get mine to seal. I was not able to use the paper gasket because the mating surfaces were slightly scored.

78-911SC · 09-19-2004, 01:44 PM

Just pulled my engine and transmission and seperated them to clean. Before putting back in car I put new swepco in. After install I'm getting heavy trans oil leaking from the top somewhere. Any ideas from where or why? Is it posssible I overfilled and it's coming out the top vent? I only went to the top of the plug but filled from the top after removing the vent plug.

Jim Sims · 09-19-2004, 01:52 PM

Vent plug may be installed wrong, vent hole must be positioned so it is within the 90 degree sector pointing forward.

K. Roman · K. Roman's Garage

What is the name of the gasket? I only see a whole gasket set on the Pelican site. My tranny was rebuilt about 15,000 miles ago and don't think I need to rebuild.
Anyone know?

SpeedracerIndy · 09-19-2004, 05:12 PM

I would suggest using a gasket material made for sealing metal to metal. Some of the possibilities are a gasket material available at any mercedes dealership (Part #: A 001 989 61 20 10 "Silicon Sealing Compound"), and Loctite 518. I don't know if you can buy just that gasket, and I don't know if it would be worth it since it is just a very small paper gasket. I had better luck with the silicone based gasket materials.

stevej37 · 09-19-2004, 05:36 PM

My 78SC was leaking from the same plate on the bottom of the tranny. Very easy fix..just buy some silicone gasket in a tube from your local auto parts store.

K. Roman · K. Roman's Garage

Ahh, thanks. Will let you know the outcome.

djmcmath · 09-19-2004, 06:05 PM

You can get just that gasket. From the PET:
Access plate gasket -- 915 303 225 00 (that's the one you're looking for)

The other two:
915 gear housing to front cover gasket (paper) is PN: 915.301.351.00
915 differential housing to gear housing gasket (paper) is PN: 915.301.191.00

Dan

djmcmath · 09-19-2004, 06:08 PM

PS -- for gaskets in general, my latest procedure is derived from something Chris Bennet recommends:
1 - Obtain appropriate gasket sealant stuff -- Loctite 518, 574, etc.
2 - Put loctite on the gasket itself, while it's sitting on your workbench. Smear it around with your finger to make a smooth even coat. Ensure that the loctite goes on the side without the studs.
3 - Put a thin coat of WD-40 (or similar) on the side of the joint with the studs -- this is the opposite side of the side that got the loctite.
4 - Make the joint.

This works well because theoretically the next time you need to break the joint, the stud side will be easy to clean because nothing stuck to it, and the other side will be easy to clean because it has no studs in it.

Cheers,

Dan

K. Roman · K. Roman's Garage

What is PET? I'd like to get that gasket and also add some Locktite. Let me know and I'll order it promptly.

SpeedracerIndy · 09-19-2004, 08:25 PM

PET is the program the dealers use to look up part numbers. You can enter the part number that Dan provided above (915 303 225 00) for the gasket into the search box at the top of this page. That will take you to the page where you can purchase the gasket. It looks like it is a $1.00 paper gasket. Shipping will probably cost more than the gasket itself.