81 300SD - it is not the tranny that is leaking

[tyl604]

Well I finally cogitated and realize that my tranny is not/has not been leaking the tranny fluid all this time. I know because I just had a used one installed and it leaks just the same - like a sieve.

So what might be the likely culprit? The transmission place obviously did not recognize it as they put two used trannies in the SD before I got one to work properly; they did not know how to adjust the vac modulator.

Short of being a worn place in a metal line (like the cooler line to the bottom of the radiator), are there a couple of places that I should check out? Or mysterious washers or something?

Any suggestion is appreciated - no matter how far out.

Thx.

[kerry]

If it's leaking tranny fluid it can only come from the transmission, the cooler lines or the cooler. Where is the leak?

[Dubyagee]

They didnt hunt the leak when the car was on the lift?

[tyl604]

Kerry - it leaks so badly that I cannot tell. I really need to put it on a lift, clean it up, and watch for the leak - but have no lift. So it has to be the tranny, the cooler lines, or the cooler? My garage floor is so messed up that I cannot tell from whence it comes. I really do not think it is the front or back seal (guess it has them) since I have the same leak with the new tranny. Arrgh. Such a great car with an embarassing problem.

Need to do some prep work when I get back to Atlanta.

[tyl604]

Dub - obviously ignored the leak (all they did was switch out the tranny - two times). When I got it back I worked on smoothing out the shift for about a week before checking the fluid level and finding it about empty. I was floored. So I dutifully keep adding fluid but am sure the tranny itself is not leaking.

[kerry]

Seems to me that putting the car on a dry piece of ground and seeing where the fluid drops would be easy without a lift. You could readily tell whether it was at the front or rear of the transmission or a cooler line.

[tyl604]

Good idea; will try it.

[jimbonaz]

Have you considered using dye for the transmission? I know Carquest and Napa carry it. Make sure it is suitable for the transmission. Tray to clean and degrease everything you can underneath and let it dry off then run the car under the proper conditions to make it leak for a short time and then get under there and see where the oil and dye is coming out with a black light. As bad as the leak sounds I would figure you could see it drip off the cooler lines or hoses if that was the case.

[tyl604]

Jim - thanks for the idea; not something I have heard of before.

Appreciated.

[Govert]

Or put paper or cardboard under the car when you park it. That should give you an indication of where it leaks.

[SD Blue]

The prime place to look for a leak of transmission fluid is the hard lines. Check where the clamps are, as the rubber tends to disentigrate over time and the result is metal-to-metal contact. Vibration will wear the wall of the hard line so thin that it may not be readily visible without removing the clamp and watching the area, while running the engine. New hard lines are available, through a dealer, for ~$50. You can try a band-aid fix of flex line over the hard line, but in my experience it is likely to not last long.

[tyl604]

I have been wondering about the hard lines too. Good thought.

Thx.