Help with S3 oil leak

adms3

Registered User
Hi all.

I've usually been able to find answers to car problems just from browsing the forum but this isn't just a normal thirsty TFSI engine. I've got a very slow leak of oil which first appeared the week before Xmas (small egg sized patch left on drive). I whipped the undertray off to find it holding a pool of oil and a smearing of oil all over the the sump. No obvious sign of the source and too slow a leak to see dripping. Since I first noticed the oil on the drive the oil level has gone from max to half on the dip stick. Then from half to just above min in the space of 2 weeks. The last oil change was done by Audi back in Dec 16 (so its due now) but this can't be the cause as the car hasn't needed any oil top up since.

I'm the only person that drives the car so I know it hasn't bottomed out and cracked the sump. Suspect that would lead to a rather catastrophic loss of oil lol. So the only other connection is to the waterpump which was replaced at the beginning of December after the thermostat failed. I can't see how the replacement of the waterpump would be the cause of a slow oil leak but looking for some ammunition before I take the car back to the garage on Friday.

Since the pump was replaced the car has only done about 150miles. In total it's done 38k in 3 years.

Anyone any ideas?

Cheers.
 

Svenedin

Registered User
Can only suggest you wipe off as much oil as possible, top it back up and try to ascertain where the oil is coming from. Is it the sump plug or maybe the sump gasket or is it coming from higher up?

A trick might be to take the undertray off, park the car with newspaper underneath and run the engine. Then look for drips on the paper. Some leaks only happen when the engine is hot with some oil pressure.
 
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Svenedin

Registered User
Incidentally, I also can’t see how replacing the water pump could lead to an oil leak either. There are no oilways to the water pump.
 

adms3

Registered User
Cheers. When I had the tray off I cleaned the sump and let the engine run for a bit. Couldn't see any obvious source so cleaned the tray and put it back. Two weeks later I'm shocked to see it's filled up the tray again. Think I'll just have to take it to the garage and prepare for more bad news:

IMG_7084.JPG

I've read a few things on forums suggesting that it's easy to wreck the composite sump if incorrectly tightening up the drain plug but can't find any instances of cars with a slow leak like this.
 

Svenedin

Registered User
Yes I have also read that the composite sump can crack if incorrect torque is used on the sump plug. However, your oil change was done a year ago so a crack would surely have shown up ages ago? I think you should take the car in for further investigation. It may not be as bad as you think. In any case, it has to be sorted.
 

Svenedin

Registered User

adms3

Registered User
£13 part. Had oil change done at the same time so saved a bit on labour costs.

Mechanic said he'd never heard of one going on the S3. But in the last month he's done 3 waterpumps :blink:
 

CanadaA3wales

Canadian living in South Wales - Audi A3 8V 150BHP
I think you are better off posting a new thread as this one is 3 years old.
If you have the same issue as this one, then supply the link in your new thread.
Best of Luck with the leak

Also get some pictures up - Clean the area and let it run and take pics of where the oil is coming from.
Oil leaks are usually only seals or a damaged sump.
 
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