oil cooler leaking... every couple weeks

I can't seem to keep a dry oil cooler for longer than a few weeks before it starts seeping out from the top seal again. It gets worse and worse until I tighten it up or replace the seals which never last that long either. I replaced the seals on my stock oil cooler a few times before I got a larger upgraded oil cooler. Now its been less than 3k miles and its leaking again. It was torqued to exactly 19 ft lbs when I installed it.

A few weeks ago it started leaking so I tightened it up a little and rearranged the coolant hoses so that they wouldn't work the cooler loose. Thought I had it whipped and now its leaking again. I also checked and doubled checked for cracks on both the cooler and the mounting flange. Anyone else have this issue? Do they even offer the top seal for an upgraded oil cooler?

Are you seeing anything funny with the seals when you take them out?
Any damage to the sealing area, old piece of the seal or such?
When it leaks do you see it coming out from there, nothing from above?
Any leaks from the injector pump?
It's not that close to it but just a thought.

I can't see anything wrong with the seals. I started inspecting them and the sealing surface after the second time. I double checked the filter housing gasket cuz i thought it may be that but no other leaks close by.

I have cleaned the whole area up, run it for a few days and then can see the leak starting from the top of the cooler. The longer I let it go the faster it starts to leak. Once I get tired of seeing the puddle growing under my car it gets changed. Speaking of which, I'm ordering another seal right now...

Are you using OEM seals or Oreilly's, etc...? It may make a difference.
What weight oil are you using?
What has the ambient temps been when you notice leakage?
Does it leak after the engine is warmed up?

Maybe try putting a straight-edge on the filter housing to check to see if that surface isn't somehow messed up? Do that on the cooler as well.

Not sure how much work it would be to change out the filter housing, but that's an option.

Someone up in Canada has one listed:

http://canadacatalyst.ca/inventory/mk4-engine-oil-filter-housing-35‏/

Other than bad gaskets/seals and coolers I haven't heard of anything else being a problem (not a filter housing). Always a first I suppose.

Friend has a 1.8T Passat that blew the cooler oil seal in an attempt to start after sitting all night in -20*F (and colder) temps. Pumped most all the oil out when it started. She's been letting her brother and/or local quick change oil places do the oil changes. Regular conventional oil gets incredibly thick in extreme cold. Not the first time it's been out of oil either. Previous winter there were two oil filter seals stacked on top of each other.
Even so it has 230K miles on it and it still runs good. 09A automatic has never seen any attention. Some cars never quit.

Mine leaked a fine mist constantly. I thought that the cooler was bumping into the radiator shroud due to weak forward and aft engine mounts. After I put in new engine mounts and it was still leaking, I had another idea; when I installed the cooler I put it in a little sideways. I eventually straightened it by loosening the cap a little then turned it, then tightened it. The seal must have been stuck and then I knocked the seal's ears off of the cooler, because when I replaced it with the really big cooler a little while later, the seal was not on the tabs. New cooler, new seals, straight, no leaks a few months later.

But, it wasn't much more than a heavy mist leak. Once a week or so I would start to see a drop form on the oil pan and get suspicious.

I'm going to throw a crazy idea in.
Diesel fuel ruins hoses.
Maybe the engine oil is contaminated with fuel somehow?
When was the last oil change and how is the fuel mileage?

I have fixed several. Cold weather really gets them leaking.

I feel 19 ft/lbs is not tight enough. 25 ft/lbs seems to do the trick. Don't bother trying to tighten one that is leaking. It will only leak worse.

When I put them together, I clean all the mating surfaces so they are oil free. Find a way to keep the cooler from spinning when tightening, so seals don't get messed up. Block of wood etc.

Thanks for all the replies. I'm gonna order an OEM seal for the cooler. Not sure what kind the upgraded one came with. It has been pretty cold lately but this happened earlier when it was warm too. I run 0w-40 synthetic (Mobil I think?) And fuel mileage is still high 40s when it's not insanely cold. I will also try putting the seal on dry. I usually put a thin layer of oil on it just by habit.

martron said:

Thanks for all the replies. I'm gonna order an OEM seal for the cooler. Not sure what kind the upgraded one came with. It has been pretty cold lately but this happened earlier when it was warm too. I run 0w-40 synthetic (Mobil I think?) And fuel mileage is still high 40s when it's not insanely cold. I will also try putting the seal on dry. I usually put a thin layer of oil on it just by habit.

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Your not doing anything wrong, this is normal behavior in 0 degree weather for all 4 cylinder VWs. However as suggested couples post up I would increase the torque and continue to lubricate the OEM O'ring before installing. Good luck!


Bajan