captcashew

Hey, everyone! I noticed this morning on my 1987 928 S4 that there was a big puddle (about 3 feet across) of red fluid under the rear. I think it is brand new since the car has been sitting for the last few months for the winter with a battery maintainer in my garage and I walk by it every day and clearly see under the rear of it on the way to and from my daily driver.

I've only had the 928 since last fall and has seemed to be in pretty good shape. The previous owner even helped me to an end of season oil change and checked all the fluids, etc. This was in early November. Since then, it really hasn't been driven.

From what I remember, the red fluid is Dexron, which means it is either power steering fluid (very unlikely) or automatic transmission fluid (which is most likely). I'm still going to take it somewhere (wondering if I should take it to the local porsche guy or just straight to a transmission guy), but since I'm worried, thought I would post on here to get some feedback. How worried should I be?

I don't have a lift, so it's not like I can jack it up to check the automatic transmission fluid levels.

dwc928s4

Mine is doing that too. Its the tranny pan seal. I had bought one from 928 international. But made the mistake of letting a Jiffy lube put it one for me. And there is a specific torque on the bolts. They over torqued them, now it leaks again.
Go to one of the big three, get a new seal, then take it to a lube joint. But watch them put the specific torque on the bolts.

captcashew

Thanks. By big three, I assume you mean one of the big 3 928 vendors, right? And just to make sure, I'll check the fluid level before I drive it, but it should be ok to drive around to get it fixed as long as it isn't losing too much fluid, right? I'll try and get a photo of the spot underneath it tonight. Just seemed strange it went from no leak to a huge one literally overnight.

Hmm, need to find some cardboard lying around too to put under there too...

Mrmerlin

the leak could be a loose cap on the tank,
a bad O ring on the Bowden cable housing,
or a bad pan gasket,'
or leaking fluid lines,

dont drive the car till you top up the fluid or you could kill an otherwise functioning transmission.

If the fluid is leaking out of the grate under the TC then the trans has to come out and a new radial seal and front pump O ring must be installed

dr bob

Expanding a bit on what the others say:

The car, at rest with engine off, has a fluid level above the top of the little reservoir. Start the car, and fluid pumps through the top of trans, and the sump level drops a little. So fluid level is ALWAYS checked with the car level, engine running in neutral or park, after cycling the gear lever slowly through all the gears. There are two lines on the reservoir. The lower line is the "cold fill" line, good for initial fills after a fluid swap. This is the line you'll look for when you add fluid in the garage before driving the car. The top line is the normal-temp line, the one you use to verify level after everything is at normal temperature. Use the current Dexron standard fluid from a reliable brand/source.

Grab a flashlight and a mirror, and you can see the fluid level on the reservoir without lifting the car, eyes under the rightside sill just forward of the right rear tire. You can use that same flashlight and mirror from the rear to maybe get a better idea where the fluid is coming from. There are some serious cleanliness requirments that you might consider before you pull the reservoir cap to add fluid. ANY dirt that falls into th ereservoir is bad, so clean around and above that opening area so nothing can get bumped and fall in. I use a 'gear oil pump', available at exotic places like Wal-Mart as well as it regular auto parts places. I add a six-foot section of clear vinyl hose (Home Depot plumbing department) that slips over the little plastic pump nozzle. Other end drapes over things and is taped/clamped/tie-wrapped whatever so the other end sits in the top of that reservoir. Leave the reservoir screen in place. Start the car, cycle the gears, back to park and parking brake on. Now you can add fluid slowly, watching the level with the mirror. pump slowly so the new fluid can pass through the screen. When you get the level where it's supposed to be, you can pull the hose and replace the cap.


If the sump gasket is the actual source of your leak, plan on replacing the fluid and the gasket. DO NOT try tightening the sump cover bolts to try and stop the leak unless you have the correct inch-pounds torque wrench for the sump cover bolts. The correct torque is barely north of hand tight with hand just on the socket, no ratchet or other handle. If the bolts get overtightened, the pan can be deformed on the thick gasket, making a leak worse rather than better. Sometimes the pans can be straightened if done very carefully. Good News is that the sumps are common to some Mercedes models and aren't rare or overly expensive. Our 928 suppliers have them ready to send to you along with the new gasket and filter set.

captcashew

Wow, great post and very thorough. Parts of it were things I was already considering (the flashlight, mirror and pump) but others I just wasn't sure on (like the levels I'd be looking for, etc. Thanks for the info. I have found a mechanic that works on porsches and sounds very good that is relatively local (within 20 miles or so), but that was still too far for me to feel comfortable driving until I felt like it had at least topped it off and it wasn't gushing fluid.

Does it still sound like a seal that would suddenly go bad though to make such a big spot just overnight?

dr bob

It's possible but unlikely. More likely is that i's been seeping slowly for a while and you just haven't noticed it. Who looks under their hibernating car anyway? OK, a few do. And be glad you did.

Some good news is that just a few ounces of spilled ATF looks like a lake. So it's likely it isn't a lot of fluid lost. It may be something that just starting the engine topping the fluid will solve. Lip seals like to be wet all the time, and sometimes in a stored car they may not be. Every one in a while you'll get lucky and find that exercising the car will be just what it needs.

captcashew

Yeah, normally I would never look. But I know that there was nothing under there at least a couple days ago. Just that I park my daily driver right behind it in the driveway on an incline, so I literally look under the car when I pull up. If there was a giant leak under the engine, I could miss it for 3 months easy. But I just dumb luck that I'd see under the back everyday. Plus I did have a shovel next to it that I used just the other day and was looking under there. I guess if it was really small, I might have missed it and then got real big in the last day or so.

captcashew

Here is a photo I took when I got home from work. Not the best photo, but should give a bit of an idea. That is from the rear. The glow is the flash off the license plate to give you an idea of the angle. I think it is a bit larger than when I left. But I'll tackle it tomorrow.

Attachment 612450

longleader

Looks like a lot to me.

dr bob

That's less than six ounces of ATF on a concrete floor that doesn't absorb ATF. Restore the level. Drive the car. Wash the floor. Put a piece of white butcher paper under the car when you park it. Look under the car a couple hours after and you'll see where its coming from. Or the drive will get things back to normal and no leak. Hey, it could happen!

Kalspeed

Damn, that car sat for the winter......???

and folks here in Rennlist always diss PO's for lack of preventive maintenance...LOL

captcashew

I actually have seen where it is leaking from. You can see the drops forming in several places. It's probably dropping a drip every 30 seconds or so. So I've put a few containers under it to cut down on the mess a bit.

I'll get under there with the mirror, etc tomorrow. But the drips seem to be coming from the center between the rear wheels. It's hard to say where the leak is coming from at that angle, but that is where the drips are coming from.

Kalspeed

What have you driven before? Domestic or Asian. This car is older..and remember not as old as my 82 but still older.

It is, and always will be, a high maintenance Porsche 928 (there is no substitute)

Take some time to look at her twice a week during winter et al, take care of her, and enjoy her...DRIVE HER

G Man

My 84' had a leak from the vacuum modulator o ring seal. Replaced that and had another leak that I couldn't pinpoint for a while. I replaced the little vent hose that runs from the top of the fill tank to the side of the trans case. It's only about 5" long and kind of akward to get at but I have not had any drips since I replaced that line. The original line had no clamps on it so it is only the elasticity of the line stretching over the fittings that makes a seal. Once this line gets hard and brittle the leaks start. I only consider my current fix temporary at this time. For a permanant fix I want to replace the rubber line that is on there now with some silicone tubing. Not sure of the exact size to go with. I'm thinking 3 or 4 mm should do. I have not been able to find anyone local to me that sells silicone tubing by the foot. Summit Racing has a retail store in Reno and I think I can find what I need there. Still need to go check them out.