Oil leak on 1.8 T

[FrenchAudi]

My Avant just failed its French Controle Technique (CT - equivalent to the UK MOT Test), because of an oil leak.

The amount of oil lost is insignificant, but it pools on the lower engine cover and spreads all over the underside when driving.

Running the engine while stationary with the lower cover removed results in about one small drop per minute, which drips from the flange at the bottom of the block immediately below the oil filter housing, onto/into the main cross member, and eventually down from there.

It is definitely not coming from the turbo oil feed connector, which is clean and dry, which leaves the oil filter gasket, the oil cooler O-ring, and the oil filter bracket to engine block gasket as possible suspects.

There is also a very small steering oil leak from one of its cooler connections, which is obvious.

I plan to start tomorrow by putting the lock carrier in the service position, necessary to access the steering oil cooler connections, and drain most of the coolant.
This will enable me to remove the oil filter and cooler, check the gasket and O-ring, and check tighten the mounting bolts for the filter housing.

I have ordered a new filter housing gasket as a precaution, and have a spare oil filter, and a cooler with new O-ring in stock for my VW camper, which is the same as the Audi one, but don't want to use these unnecessarily.

I'm wondering if someone distorted the oil cooler sealing surface in the past by over tightening the filter, and if this is a possibility.

Has anyone here had a similar small leak, and what was the cause, please?

[Crasher]

I would say oil filter bracket gasket, 028 115 441 C or cooler O ring N 901 442 01 as these go very hard with age. Don't forget the bolts N 901 442 01 x 2 and N 903 396 01 x 1. Thinking about it, more likely the oil cooler O ring than the gasket.

[FrenchAudi]

Thanks Crasher, that's cheered me up a bit. I'm hoping it's the cooler O ring, as it's the easiest to replace, but Sod's Law may apply.

I just realised I can access the steering oil cooler without moving the lock carrier. The leaking connection is on the return hose from the rack, the fluid seems to have turned the rubber to jelly.

I'll see if I can get away with cutting off a few cm's to good hose.

[FrenchAudi]

I have removed the oil filter and cooler, their seals are intact and don't seem to have been leaking.

After cleaning up all the mess of oil I find that oil seems to be weeping from the aluminium casting of the filter housing/bracket in the crevice between the two mounting bolts at the bottom, where the flat surface for the RH bolt begins. See picture below, the RH bottom bolt is not shown, but its position can be seen from the gasket - just where the red ring crosses the gasket.

I have cleaned the area and everywhere above and around it a few times, but a film of oil still appears in the crevice. The housing seems to be either porous or possibly cracked due to excessive force when tightening the filter.

If oil leaks visibly like this from just whatever is left in the space behind the housing, the leak will be much bigger when the oil is pressurised.

Has anyone come across a similar leak?

Oil filter housing.jpg

[Crasher]

Probably corrosion between the ally filter holder, steel gasket and iron block.

[FrenchAudi]

Probably corrosion between the ally filter holder, steel gasket and iron block.

Or brute force vs a flimsy bracket with heavy items hung from it.

I'll take the housing off tomorrow and have a good look at it to see if it's repairable with epoxy or similar, but it might just fall apart when removed.

If not repairable I need a part number to get a new one, as there seems to be a variety of filter housings used on 1.8 T engines, and an old on Ebay might be just as bad.

[FrenchAudi]

I was relieved to find that he housing is not cracked; the oil must have been running down in a thin film and collecting in the crevice before dripping further.

I replaced the O ring for the oil cooler and the gasket for the filter bracket, which I obtained from a French supplier, Mechatechnic, for €1.95 and €2.55 respectively, and the leak has stopped.

There is a minute leak from the sump drain plug, although I fitted a new crush washer when I last changed the oil, but I'm not going to replace that right now.

Now I plan to clean the oil off the underside of the car using white spirit with my cleaning gun, with some large sheets of cardboard underneath to absorb the mess, which I will burn afterwards.

I have also ordered some large oil absorbent pads. (Pack of 10) Premium Oil Absorbent Pads/Mats (Oil/Fuel Only) : Amazon.co.uk: Automotive

I will put a couple of these on top of the lower engine cover to catch any future leaks or spills, such as when changing the filter, which will stop them coating the underside of the car, and be easier than cleaning the cover itself.