DavidI

Hi Folks,

I hadn't used the car for a week and took it out yesterday morning (after jump starting) for a 90 minute blast to charge the battery. Parked up on my return and noticed 4 hours later that a patch of oil had appeared by the front left corner. The oil area was about 30cm long and 10cm wide, so quite large, but thin - my drive is fairly steep so the oil had dropped from the car and 'slid' down my drive.

The exit point from the car appeared to be the small gap between where the left suspension control arm pokes through between the metal base of the luggage compartment and the front plastic undertray. Oil has rolled forward on the undertray from this point (I guess while on the drive) and also blown backward while on the move. The oil is very clean and feels low viscosity, almost like machine oil. I had a major service a couple of months and maybe 1,000 miles ago so I would expect oils to be clean.

I'm guessing a final drive leak; the car has dripped a very little oil from here since I've had it. I'll get it on a flatbed to the shop as soon as they can take it.

Any chance I'm barking up the wrong tree? I guess any fluid could drip from between the two underbody trays, so position of leak is not decisive, but I've checked things like PAS fluid and brake fluid and they seem OK?

robmug

I can't help with the oil leak, but I was concerned by your 'jump start' comment.

You'll trash the catalyst by jump starting - (I assume it's the same for the Porsche metal catalysts...)

DavidI

I jumped it from the old RR, rather than a push start!

garrett376

What type of oil was it?? Did you smell it, or wipe it so you know what color it is?? Could be brake fluid (check hydraulic pump), power steering fluid, or tranny fluid from your differential. I'd bet it is not your differential fluid - if it leaked that much, that fast - you'd probably hear the difference! And, those things are not common leakers, like the brake system, and/or power steering system.

Grab a 10mm socket and a screwdriver and remove the undertray to check out where the leak is coming from. And check around your spare tire to see if brake fluid is leaking there.

DavidI

Thanks Garrett - the oil was really just like machine oil, very clean and quite thin with a gold colour. Brake fluid and PAS fluid were both topped up so I don't think it's those; I took everything out of the front compartment expecting to find brake fluid everywhere as I checked the reservoir at dusk on Saturday and it looked empty, but wasn't. I'm out of sensible ideas, leaving me with the front drive unit as the likely culprit....

Michael Gibney

Hi David,

Three types of oil in the front area.
1. Power steering fluid - usually red in colour.
2. Brake fluid - various colours but distinctive tase - once sampled never forgotten!
3. Front diff oil - various colours but mostly honey coloured if not years old.

As a guess you have front diff oil.
Six ways for the oil to get out -broken casing aside.
1. loose or lost drain plug - not likely.
2. loose or lost filler plug - not likely
3. Input shaft seal faulty - possible
4. Left or right output shaft seals faulty - possible
5. breather vent hole - would have to be very overfull - not likely.

If you take off the tray you should be able to see - it will be obvious.

But - interesting possability to consider - if the front diff unit was overfilled at the service - and that is hard to do because when the filler hose is removed the over fill oil flows back out before you get the filler plug screwed back in - but a really determined but not too smart mechanic can get the diff very overfull and then quickly get the plug screwed in so as to end up with an overfull diff and a smile as he thinks "wow - more oil = better". Then all is ok for a while because the oil is cold and the seals although ok are a bit old and when "flooded" with hot thin oil they leak - especially if the breather is blocked - so you get a leak when the car has been for a good run - just like you said.

The abovementioned blocked breather is not an essential element in the leak theory but it makes it more pronounced - no breather = pressure to "push" the oil out. A smart mechanic would pick up on a blocked breather when draining the oil because if the draining oil "glugs" you have a blocked breather and if it flows fast and you have a clear breather. BUT some mechanics loosen the filler plug first so they can be sure they can refill the oil after they drain it because sometimes the filler plugs are damaged by previous idiots using ill fitting hex head keys BUT a good mechanic can always get out a damaged filler plug - it is part of routine service work.

Sorry to have gone on and on but it is interesting to think about fixing Porsches when it's nearly bedtime and too late to go and play with mine.

Regards, Michael Gibney

joey bagadonuts

Are you sure it's not from the brake fluid overflow hose? The skinny plastic pipe exits at the base of the wheel well liner, right behind the front left wheel.

If you've topped off your brake fluid beyond the "Max" line, used the brakes aggressively or both, fluid will drip out of this hose. The fluid is also clear and oily so hopefully that's all it is.

DavidI

Michael, that's great, I appreciate the effort bedtime or not! It's not the first spirited drive since the service so I'm leaning toward item 3 or 4 being most likely, backed up by the fact that the specialist mentioned a slight leak from the front diff at the recent service.

Thanks Joey, I had no idea there was an excess fluid vent/hose. I didn't go as far as tasting it (do people really do that?!?) but this was really like thin oil. My main reasons for thinking diff oil is more likely are 1. I've driven the car quite hard since the service and would have expected to see the same puddle. This is countered quite easily by the amount of rain we've had this summer and I could easily have missed it, but 2. the drive slopes forward and to the cars left, so I don't think the brake fluid would have made it from the arch to the control arm.

I drove the car 20m onto the flatbed and the buzzer and warning light sounded, not at start up but after 10 seconds or so, and then went out, so I'm hoping if it is the diff then I've caught it before doing any serious damage.

joey bagadonuts

Probably a correct deduction BUT the overflow tube is not exactly welded into place. The plastic pipe could be redirected so that fluid would flow under the car. If it's still in your possession (flatbed=shop, right?) then have a look. It's a skinny black pipe (2-3mm) with an angled tip--looks like a loose bit hanging out from under the bodywork. Check the fluid level, too, on level surface to see if it's within spec.

If it's too late, make sure your mechanic checks it as well and follows much of Michael's excellent advice. Good luck and keep us posted.

DavidI

It has made it to the shop though they won't look at it until tomorrow or even Wednesday. With luck it will be an easy spot with the trays off. Thanks again for the input!

DavidI

The shop got the car on the ramp this afternoon and apparently the input shaft is gushing oil. They reckon 10 hours to free the diff from the torque tube and supension and refit all the seals (they'll do them all while they've got the diff free) plus another £70 or so in consumables, followed by an alignment check - front wheels only as all four corners were done recently.

I'm hoping there's no damage to the diff itself and the garage never mentioned it until I asked so I suspect you normally hear if there is a problem, as Garrett suggested!

Could have been worse and I get this weird double-edged feeling whenever something like this goes wrong with the car (and there have been a few) that I don't mind parting with the money if it makes another part of the car good as new again

Thanks for the help, as ever.

C H

Anybody ever change the I/P and O/P seals themself? Mine are all leaking, the O/P don't look to hard, but it sounds like a terrible job to do the I/P seal if it is 10 hours of labour! If anyone has done this let me know about your experience, and if anyone has paid to have this done give me a ballpark figure on cost so I can brace myself for the shock.

Thanks
Curtis

Sten

Have replaced the front diff completely, took two of us about two hours with the car on a lift. The tricky bit is undoing the bolts that hold the torque tube to the diff, the only way to reach the top bolts is using a variety of 3/8 drive extension bars and a universal knuckle to go in 'over the top'. I think I also remember having to drop the steering rack slightly, and then remove the diff using 'judicious levering'. As it turned out, there was nothing wrong with the diff, and that's with 174.000 miles on it. I can take some pictures of the diff that was removed, but you'll have to wait until next week as it's locked in someone else's workshop!
Barry

C H

I had the pan off already and had a look, the diff shaft doesn't look fun. I can feel gear oil in the little inspection hole, so it is leaking for sure. As for the seals, anyone know how they come out? I am guessing that you just use a seal puller and then tap the new ones in, but Porsche seems to do things a little different.

Sten, any pics of the I/P side would be great

Thanks
Curtis

Sten

Hope this helps - taken as if you were looking toward the front of the car from underneath.