1980 450SL slow transmission leak

[rmasteller]

I'm getting serious finally about selling this car. Want to set some things straight before trying to hand it off. Just replaced the alternator last week.

The transmission has had a slow/intermittent leak since I got the car in 2012. The underside of the engine/transmission is a mess (I'll post pics later), so it's difficult for me to find the source of the leak. I've let it go for years because I have a drip tray under the car to keep the garage floor from being stained and it is easy to refill.

What's the best way to locate the source of the leak?

[rmasteller]

Step one is going to be cleaning, and I plan to do the following:

In the gravel driveway at home:
+ Put front end on ramps.
+ Spray a degreaser on everything I can get to underneath, and from under the hood.

In the DIY wash bay:
+ Put front end on ramps.
+ Repeat degreaser spray treatment.
+ Use car wash wand on "engine degreaser" setting, then wash setting, then rinse setting.

Wearing disposable clothing, long sleeves/pants, gloves, eye protection.

Many people talk about using brushes to scrub the grime away and I don't think I'll be doing that underneath at the DIY car wash bay. I know discussions on cleaning are like discussions on motor oil where there will be a wide variety of strong opinions. Knowing it can start a flame war, please chime in if you have any recommendations for me! Be kind to one another.

It will be interesting to see how messy the car gets just on the drive home from the wash bay.

~~~~~~~~~~~~

Step two is identifying the leak. The puddles appear on the passenger side. But, who knows where the flow originates from and what parts the fluid flows across to get to that low spot to drop from?

I've been reading more about transmission leaks. Is this a complete list of all the possible culprits?
- Pan
- Fill tube connection
- Kick down connection
- Gear selector connection
- Lines to radiator
- Seal between transmission and engine

Some people say the torque converter can drain - what's up with that? Why/how can that happen, and how would I know if that's my issue?

Thanks!

[Sugar Bear]

Rodd,

I would not get under a car on most ramps and I would never get under any car on any ramp that is resting on gravel. Gravel is a loose substrate, ramps need to be on a solid level surface.

Good luck and work safely!

[rmasteller]

Really?? I know to never go under if the car is on a jack, but jack stands and ramps are always the safe support methods. No?

And regarding gravel, the drive is level and my ramps are solid. Maybe not this exact model, but something like this:
https://www.raceramps.com/ramps/p/rr-56/

[Sugar Bear]

I've had both jack stands and ramps fail. The stands were low quality and the car was heavy. I was young and learned from it.

The ramps were not on a completely flat surface i.e., an angled driveway. A friend's Dad stopped by, I got out from under the car and the ramps slowly twisted and collapsed. I attribute this to the angle of the driveway and the quality of the ramps.

All support stands and ramps should be in excellent condition, well within their weight ratings, be on a solid surface, positioned properly and have a backup support such as old steel (not aluminum) rims under the frame rails.

Good luck, work safely and have fun!!!

[rmasteller]

Thanks for the information and clarification, Sugar Bear. The race ramps are solid material, and they'll be on level surface. Or, maybe I'll drop a tarp in the garage and do the cleaning that way, with a box fan running to blow fumes out the garage door.

Anyone have any further advice on my plans? Any other possible sources for leaks? This is the 3-speed auto transmission.

I'm concerned driving back from the wash bay will just blow any fluid leaks around again and the source of the leak will be hard to find again .

[Sugar Bear]

Common leak areas are the front pump seal where the torque converter snout goes into the front pump, on the right side at the two piston covers, these can mimic a pan gasket leak. If it looks like the pan gasket is leaking on the right side study the two round covers just above the pan. Next would probably be cooler lines.

Good luck!!!

[ceualauren]

Some people say the torque converter can drain - Movie rulz what's up with that? Why/how can that happen, and how would I know if that's my issue?

[daantjie]

There is a 5mm hex drain plug in the torque converter. You need to turn the engine so it becomes visible from below.

[Sugar Bear]

@ ceualauren

Some torque converters have a drain plug, some do not. The drain plug is useful when doing a transmission service as it provides for a more thorough draining of the old fluid, approx 2 quarts. Those same 2 or so quarts often drain out of the neck of the torque converter into the pan. When the level gets too high in the pan it will leak out from other seals or a vent tube. This leakage usually occurs on vehicles that sit for months or longer. These same vehicles may not leak at all in frequent use scenarios.

Hope this helps...