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Danny, VW Mechanic
Category: VW
Satisfied Customers: 4004
Experience:  ASE Master Certified with L1 Certification, Volkswagen Certified, VW and Audi repair shop owner
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Passat: it has an oil leak at top of oil filter housing..gaskets..blow

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I have a 1999 WV Passat--it has an oil leak at top of oil filter housing, as best I can tell. Pumps oil at even when starter turns motor over. I have re-seated plug at top of housing--did not fix.

Are there gaskets/o-rings at top of housing that can leak/blow-out???

There's a few seals and a few gaskets. Here's a picture of the system. Number 6 is the oil supply line to the turbo, it has a seal numbered 8 in the picture. 9 is an oil pressure sender which has a seal built in, that can leak, the sensor can also fail and leak. Number 11 is also a sensor that has a seal or the sensor can fail and leak. Also there's a seal between the oil cooler and filter housing which is number 12 in the picture. That's the most common thing that leaks. You need to get carb cleaner and clean the housing off really well then have somebody crank the engine and observe exactly where the oil is pouring out.


Customer: replied 7 years ago.



What holds the oil/water cooler housing (13) against the oil filter cast housing?? Is it nut(14)?? (I would like to know before I take this unit apart)


I believe seal 12 is the problem-- just from my observations.


I just wanted to be sure of the parts order since I had no print/schematic to go from before you sent this print.


In case I am unlucky--how does the cast oil filter housing (10) seal against the engine block?? Is it just the gasket (5)?? How likely is it that this gasket/seal has failed??

Is part (12) an o-ring?? Easily available from a dealer? Is Gasket (5) ALSO READILY AVAILABLE??







The filter housing is bolted to the block yes. It's a metal gasket, I have never seen one leak before, also never seen the housing break without the car having been in an accident. 99% it's that seal number 12 which is about $10 at the dealer. You remove the oil filter, then there's a 24 mm nut that sandwiches the cooler too the filter housing. This is very common, I've got a car on its way to my shop with this problem right now. All the gaskets are available, number 12 they definitely should have at your dealer because it's used on all VWs basically since the 80s. The rest of them they probably don't stock because they never fail (except possibly the oil supply o-ring).

To remove the oil cooler you might have to drain the coolant so you can remove the hoses from the cooler but I'd attempt doing it without draining the coolant first and then do it if necessary. There's a drain that's accessible from the front of the radiator on the driver side you have to remove the lower driver side grill to access it.


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Customer: replied 7 years ago.









Customer: replied 7 years ago.

Danny: If I can continue this question--willing to pay additional.


I fixed the starter, fixed the oil leak--but engine will not now run.


What I know:

-As soon as I replaced the starter, I tested it and the engine started in 3 piston compressions--I shut it off because I had not replaced the A/C belt.

-I then replaced the A/C belt and noticed the oil leak we discussed before.

-I cranked the motor several times after the first short run to try to find the oil leak--the motor would never start again, but did fire several times on 1 cylinder.

-I then used your feedback to fix the oil leak--but could not get the motor started again. I did refill the lost crankcase oil so that I would not get a low oil lockout/shutdown signal.


-I then pulled the plugs--No. 1 very oily in boot, in plug gap area and could have shorted. The remaining 3 plugs were relatively clean. I cleaned all plugs, checked the gaps in-spec, checked all for spark-->spark was/is strong on all plugs.

-Tried to start the motor again, would not run but there were several cylinder firings.

-Pulled the plugs again--they were dry. I sprayed a little starter fluid in each and replaced thinking that with good spark, the starter fluid might kick the engine over. Same results as before. I then loosened the intake rubber boot to the intake manifold and tried to start the motor again while spraying some starter fuid into the maniflod. Still would not start.

-I puled the plugs again--they were very wet--thought I might have then flooded the plugs.

-I then used a piece of tubing on an air hose and blew into the top of each cylinder with the plugs out to dry out each cylinder, then dried and replaced the plugs.

-I then tried to start the engine again, but it would not run--only got one firing pop from 1 cylinder--that is even less response than beofre.

-I then pulled the plugs again--re-verified spark to each plug.

-I then checked the fuel pump outlet pressure into the fuel rail--80 psi. I checked for water in the gas being delivered to the fuel rail--none detected.

-At this point I cannot understand why the engine will not run, especially since it started up quickly right after I replaced the starter.????

-Then, I got my son's VW diagnostic computer program/cable since he also owns a WV and uses this setup successfully on his car. When hooked up, the computer scrren stated that connection could not be made to the car's computer. I then bought a different style OBD II Hand Held Scanner and cable--this scanner also said that it could not connect to the car's computer. Therefore we could not diagnose the causes.

-At this point we thought that the car's computer could be defective--but that does not make sense because the engine has good spark, the starter engages/turns over the engine, the dash warning lights work, and the fuel pump operates as it should??

-We did find a leak in the vacuum hose to the fuel rail pressure regulator and we replaced that hose.

-I know of nothing that I've moved or disconnected since replacing the starter and the inital engine start that might cause this problem.


-One change since the initial engine start is the oil leak at the top of the fuel filter that we discussed previously--oil is now over/run down the driver's side of the engine in a spreading v-pattern-->could this oil have gotten into a relay/sensing device that could cause the above mentioned problems?? This is not something that I can easily clean in my driveway.


-I need your help at this point--I have tried what makes sense to me. There could be a third failure of some component but a 3rd failure after the starter and the oil leak seems fairly unikely??


-Any suggestions??? I'm afraid if I just take it to a dealer, and the computer diagnostics is defective, I could go through a very expensive Easter-Egg Hunt.


Please reply.





This is very common on the V6 model Passats and I actually have a 1.8t in the shop here right now doing the same thing.

Engine rotates a bit fast like lack of compression? I think you flooded it. Remove the fuel pump fuse its the third from the bottom on the left row of vertical fuses on the side of the dash.

Hook a battery charger up to the battery on normal charge mode, or use jumper cables. Then crank the motor over while somebody puts starting fluid in the intake. It should start to fire up, once it does start feathering the fuel pump fuse in and out.

Customer: replied 7 years ago.



I tried what you suggested--it made sense for the symptons.


I got the engine to fire several more times while cranking, following your suggestions, but I could not get it to run. I tried this approach numerous times.


What I don't know is that if your suggestion is a "very narrow window" of getting the conditions just right to get the engine to run by this approach and I just did not hit that narrow window, --or if their is another problem.?


For more information, my son worked on this car independently for a while. He found that the ABS (brake system) module was faulty and that was why the diagnostic computer devices gave a "could not make a connection to the on-board car computer". He disconnected the ABS and now both of our computer diagnostic devices connect to the car's computer. However, both diagnostic systems do not indicate any problem issues????


Is this another indication that the flooding that you described is still the most likely cause??


On another note, that I forgot to put forward in my earlier email: I thought the the engine timing may have slipped. I pried open the top of the timing belt cover--belt looks relatively new and is very tight--does not seem likely to have slipped, but I couldn't tell. If this could be an issue/problem, how do you check the timing on the crankshsaft with the camshaft without taking the front of the car/grill off?? Are the timing marks visible fron just the top-front timing belt cover, and the bottom of the crankshaft?


For the electrical timing part of the engine operation, is that not controlled by the car's computer, therefore, if the computer diagnostics shows no problem, then the electrical timig is not the cause of problems?


Thus/bottom-line, if the timing is not a likely issue--is the flooding still the most likely cause, and I need to repeat the process in your last reply until I can get the engine running? Or might there still be another cuase of the no-run problem?


(I'd sure rather tune my old 79 Corvette than this VW!!)


Thanks for any further suggestions.

Ok, so for the ABS module you can remove it and send it off to rebuild at the instructions for removal are on their site although I recommend taking the driver front wheel off and removing the fender liner it's MUCH easier than trying to use a small bit driver to do it like shown on their site. The rest of the process is the same so take a look at their pictures.

The trying to get it to run is a very narrow window yes it isn't easy at all.

The 1.8t I did yesterday I had to remove the fuel pump fuse, remove the spark plugs, clean them off, blow air into the cylinders to clear the flood, then add about a tablespoon of oil, crank the engine until it starts sounding normal again (20 seconds) and then as I was cranking just barely tap the fuel pump fuse into position for like a 10th of a second, the car starts to fire, tap the fuse again, the engine is almost fired up, tapped it again and it fired up then I jammed the fuse in and reved it to 2000 rpm for about a minute. Then it would run. Also all of the cranking is done with your foot all the way on the gas pedal to get max air in the cylinders.

The reason I KNOW this is the problem is because every time this happens to one of my customers the story they give is "I started the car to pull it out of the garage, forgot something in the house, shut the car off then it wouldn't start." or something very similar. It's caused by starting the car, not letting it get into the point where the oxygen sensors are working and it isn't just dumping fuel, and this causes the flooding.


Edited by Danny on 1/6/2010 at 5:25 PM EST
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Customer: replied 7 years ago.



Thanks for your response. This start-up is indeed a 'very narrow window". After several repeated attempts, we finally got the engine started.


Truly, thanks again.

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