Oil leak between oil filter housing and oil cooler

Joined
Apr 7, 2014
Location
Finland
TDI
VW Passat 2000 1.9L TDI 85kW AJM
I have a leak in B5 Passat 2000 with AJM TDI 1.9L engine. The oil seems to be leaking between the oil filter housing and the oil cooler (water cooled). I have marked the leak position in the image below (not from my car but similar enough looking part that I believe this is the same part): https://imgur.com/oQAErLx

The amount of oil leaking is not a problem for the engine itself so I have some time to figure out how to best proceed with the fix. However, I cannot just ignore the problem due the mess the oil makes.

Can you provide any pointers?

Is it possible to somehow tighten the seam (connection between the filter housing and the cooler)? Assuming, of course, that the seal just leaks and is not totally broken.

Do I need to remove all oil and water before doing any maintenance for this part?

Is this a common leak problem? Are there any preventive measures to avoid leaking from the same source again?

Does anybody have an exploded view of the construction of filter housing + cooler combination?

(Some additional text description to help finding this post in the future when you don't know the name of the things above: there seems to be leaking oil above the cube attached under the oil filter. The cube has two water connections.)
 

vwztips

Veteran Member
Joined
Aug 30, 2009
Location
Greenville, SC
TDI
2005 Passat GLS Wagon TDI 5 spd manual w/BSM delete 2011 Tiguan TDI/DSG 2005 Audi A4 Avant 6MQ TDI 2011 BMW X5 35d
This large diameter o-ring can/will harden over time and leak. Best to just replace it.
 

jayb79

Top Post Dawg
Joined
May 20, 2000
Location
Exeter,NH
Common problem on aging oil cooler o-rings. Easy enough job to replace it but it is very messy. The large flange at the bottom of the cooler simply unscrews and the cooler seals are easily accessed.
 
Joined
Apr 7, 2014
Location
Finland
TDI
VW Passat 2000 1.9L TDI 85kW AJM
Common problem on aging oil cooler o-rings. Easy enough job to replace it but it is very messy. The large flange at the bottom of the cooler simply unscrews and the cooler seals are easily accessed.
Thanks for info. Do you know if I can do this without removing all coolant and/or oil from the engine?
 

jayb79

Top Post Dawg
Joined
May 20, 2000
Location
Exeter,NH
I did mine without removing the coolant hoses, oil will be lost but only what is left in the cooler and the bottom of the filter (less than a quart). Run the motor and let is get the oil warm, then shut it down and open the filter housing so the oil can drain down while the motor cools.
 

burn_your_money

Veteran Member
Joined
Oct 16, 2012
Location
Missouri
TDI
99 Beetle, 96 B4V, 05 Passat wagon
I just did this last week on mine. I needed a 32mm wrench. I had to cut it in half (around 8" long) and used the box end. There is 1 o-ring at the top and 1 square edge o-ring at the bottom. I bought the seals at the dealer for about $18.00. I didn't drain the coolant or the oil. I lost around 1/2 a liter of oil but caught it all with a standard oil drain catch pan.



gaskets
https://www.idparts.com/oil-cooler-gasket-set-a4a5mkvi-p-6504.html


exploded view
http://www.oemepc.com/vw/part_singl...hg_ug/115/subcategory/115070/part_id/0/lang/e


Part 14 on mine had a shaft (like a hollow bolt) running up that held everything together.
 
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