Squealing noise and oil leak from front diff area

Hi I have just discovered an oil leak at the front of my 2004 C4S tiptronic. Before I noticed the leak there was an occasional high pitched squeal from the front of the car (like a fan built slipping) which lasted for a couple of seconds and then disappeared. I assume the noise is the oil being pushed past the seals from the diff. I will be taking the front splash guard off this weekend to see if I can see what is happening. Could anybody advise on what I can expect to put it right? thanks in advance Graham

Is the oil gear oil or hydraulic fluid? That's the only thing you have in the front of your car. It's probably hydraulic fluid, which would indicate a power steering fluid leak from the steering rack. The power steering will squeal when the fluid id low, especially when you turn the wheel. Check your PS fluid, if it's low, it's likely a leak.

I hate to tell you this, but your description of symptoms above sounds exactly like the symptoms that I experienced in my C4S when the front differential failed. It sounded like a slipping belt in the front, and I really noticed it on deceleration. I also had a leak in the front that left a noticable spot on the garage floor. Porsche doesn't consider the front differential unit to be servicable. A dealer will order a new front differential and replace the entire unit. The part is roughly $7K US, and you'll add the labor on top of that. Another option is to buy a used differential. There are many available from salvage cars or from people who convert their turbo or C4S into a RWD car. Some come with a warranty, and the price varies depending on the mileage, etc. I found these units to be roughly half on the cost of a new unit. In my case, I was fortunate enough to have a local independent mechanic who was able to locate all the parts and rebuild my front differential. The gears in my differential were not damaged, but the bearings were in very bad shape. One of the bearing cages was broken open and ball bearings were close to being released inside the differential case. I also had my viscous coupling replaced. The rebuild was a great option for me. It was roughly $3,500 and it took about 3 weeks for the repair, including finding the parts (several came from Germany). Sorry to be the bearer of bad news. I hope your situation isn't as bad as mine was, but it sounds like it might be. Good luck.

Hi I jacked the car up on one side and to my relief when I tried rotating the wheel it had some resistance (similar to pushing up a damper). Which I am told is a way of checking the viscous coupling. Consequently I jacked up the front and put the car on blocks giving me enough clearance to get under the car and remove the splash shield. Again to my relief there was no leak around the driveshafts (completely dry) there was however oil further back near to the filler plug which I suppose indicates that this is the problem. (I have taken a few pics which I hope to show tomorrow if I can find the lead to download to the pc). Is there anywhere else that it could be leaking from? The oil stain is gathered at the back of the housing and is at a level up to just above the filler plug (which I find slightly confusing) and is completely dry above that. The OPC had it in to change the diff oil and stripped the thread of the filler plug and got a company in to cut a new thread with a helicoil I think. I have to say that looking at it I am surprised it is leaking. I am in a bit of a catch 22 in that if I remove it, the angle of the car will make the oil run out as I want to check the level. I guess I will have to get some more blocks together to raise the car all round to make it level and then check. Is there anywhere else that I should be looking? cheers Graham

A suggestion. Remove the diff, very easy. Push out old side bearings and replace them. Refill with diff oil and see if that fixed the problem. Bearing will cost $30, seal around $25. With fluid change you are in the neighborhood of $150. Search on google for photos and description of the job.