Diagnosing a stuburn oil leak

Cabrales · Nov 13, 2012

2003 Jetta TDI Wagon, approximately 150,000 miles.

I've had an oil leak for about a year now. I've had two mechanics look at it and they can't find the source. The mechanic who is looking at it not is stumped. He says he can see the oil running down the back of the engine, and oil seems to be coming from the intake manifold and exhaust manifold bolt (I may not be translating this correctly). He said he can't make out where that oil would be coming from. FYI, he is not a TDI mechanic. He is a close friend who works out of his house, and I left the car with him about a month ago so he can get to the bottom of this. Before that I took the car to one of our gurus who also couldn't figure it out.

Any thoughts?

oilhammer · Nov 13, 2012

The ALH engine is a VERY simple engine... it simply does not have many places that oil CAN leak. So I am somewhat perplexed as to why someone looking at it couldn't figure it out.

Since you said it is up high, but not which end of the engine, is it possible the vacuum pump is leaking?

Cabrales · Nov 13, 2012

Oilhammer, the way he described it is a good amount of oil that looks as if its coming from the area of the intake manifold/exhaust manifold bolt. But he said he doesn't know what could be leaking to have oil show up there. The oil looks is on the back of the engine, and if I recall correctly, closer to the driver's side.

oilhammer · Nov 13, 2012

Yep, sounds like it is in the area of the vacuum pump, but maybe could be something with the valve cover, although those rarely ever leak.

JB05 · Nov 13, 2012

Could the EGR be the cause of such a gross leak?

Cabrales · Nov 13, 2012

We replaced the valve cover & gasket, thinking this is where the leak was coming from. It didn't make a difference.

YEAAAAH · Nov 13, 2012

Is the oil coming from/on the turbo? Perhaps the oil lines on the turbo are loose.

IndigoBlueWagon · Nov 14, 2012

Like oilhammer said, the ALH engine isn't complex. If a guru has had it for a month and can't find the problem I'd get it to someone else for diagnosis.

Cabrales · Nov 14, 2012

Indigo, just to clarify. I took it to a guru who had it for a couple days but couldn't find the source of the leak. It is now at a friend of mine who is a mechanic. He has no experience with TDI's, but is willing to spend lots of time with it, repeatedly cleaning the engine compartment, and running the car to see if he can locate the source of the leak. But as I said, all he can see is the oil coming from the bolt at the intake and exhaust manifold bolts.

Cabrales · Nov 14, 2012

Thank you all for your help. The ideas floated so far have been the vacuum pump, egr, and oil lines on the turbo. How would I go about checking those individual parts?

turboii · Nov 14, 2012

i actually have a leak in the very same spot. it looks to be coming from the where the intake manifold bolts to the head on the far drivers side. i havent taken anything apart yet to be sure though, hoping someone else who has fixed it before speaks up

Cabrales · Nov 14, 2012

Turboii, your description sounds like what my guy said. I'm sure we are not the only ones who've had this problem.

Herm TDI · Nov 14, 2012

When performing any oil leak tracing start by washing the engine.
From the discription that "cabrales" provided I would replace the vacuum pump seal and remove the valve-cover. Clean the sealing surface and then apply a small dab of sealant

At the corners where the valve cover "arch" mates to #1 & #5 bearing caps.

These are the two most common oil leak areas on the driver's side of the engine.
Sealant P/N: D-176-404-A2

turboii · Nov 14, 2012

im thinking its the vacuum pump seal too..

http://forums.tdiclub.com/showthread.php?t=328336

ordering it now, will post results.

next i will try the valve cover. i just discovered apparently you cant replace the valve cover seal without ordering a new valve cover, and its $170

http://www.idparts.com/catalog/product_info.php?cPath=29_125&products_id=654

Cabrales · Nov 14, 2012

Sorry for my major lack of knowledge. Is there a thread that shows where the vacuum pump is, and better yet, the steps for replacing the vacuum pump seal?

Cabrales · Nov 14, 2012

I just talked to my buddy (the mechanic), he said he checked the turbo already, the lines are good and the turbo area dry. He's going to check the vacuum pump later today.

Ohnoitsthexops · Nov 14, 2012

I have a leak on the bottom/ back by the dog bone that it thought was coming from the main seal. But this made me want to see if it could be from the vaccume pump now

Newflee · Nov 15, 2012

Drivers side of the engine attached right on the side of the valve cover/head. You will feel and/or see a finger size black rubber pipe leading from it to the firewall where it attaches to the brake booster.

Newflee · Nov 15, 2012

looks like thishttp://www.google.ca/imgres?um=1&hl=en&safe=off&sa=N&biw=1366&bih=635&tbm=isch&tbnid=avGMkpuXtWLJlM:&imgrefurl=http://www.ebay.com/itm/Genuine-VW-Golf-MK4-Bora-1-9-TDI-Vacuum-Pump-90-BHP-AGR-AHF-ALH-038-145-101-B-/320993471629%3Fpt%3DUK_CarsParts_Vehicles_CarParts_SM%26hash%3Ditem4abcb3ac8d&docid=XgUxcp_dddyEdM&itg=1&imgurl=http://i.ebayimg.com/t/Genuine-VW-Golf-MK4-Bora-1-9-TDI-Vacuum-Pump-90-BHP-AGR-AHF-ALH-038-145-101-B-/00/s/NzY4WDEwMjQ%253D/%2524(KGrHqNHJBUE63VVILHMBOzlkuJH2Q~~60_35.JPG&w=300&h=225&ei=PMOkUMygKaSj2QXz7IDIAw&zoom=1&iact=hc&vpx=1089&vpy=281&dur=498&hovh=180&hovw=240&tx=186&ty=61&sig=107335249858158179869&page=2&tbnh=136&tbnw=182&start=18&ndsp=24&ved=1t:429,r:35,s:0,i:179

lojosh · Nov 15, 2012

I have a small oil leak on my 01 TDI, could not figure out where it was took it to a trusted mechanic. he looked at it and one of the problemshe found was the O-Ring going into the PCV valve was not a tight fit. He replaced it. I have not checked it out since he replaced it, i plan on looking it over today. But i will get back later today and give an update.

moterhead · Nov 15, 2012

Check your oil cap i had a leak there

Cabrales · Nov 15, 2012

Thanks Newflee. That helps me visualize. My mechanic still has the car, so I'm sure he knows where the vacuum pump is.

vwdsmguy · Nov 16, 2012

oil leak

I made a similar thread and was told that it could be from the back of the head gasket, but have not pulled the head yet until i'm sure. Actually the amount of oil lost is minimal because a little spread out looks like a lot.

sootie · Nov 16, 2012

Only difference with the head gasket leaks is that it will leak below the manifolds. Very hard to figure out if you did not think that there was an oil passage there.

turboii · Nov 26, 2012

replacing the vacuum pump seal appears to have fixed my leak

nokivasara · Nov 26, 2012

VW's doesn't leak oil, they just mark their territory...

At least that's what we used to say when me and my freinds had old 1.6 n/a diesels, I very much doubt there is a single old VW diesel that doesn't leak any oil. TDI's seem to be better.

Diagnosing a stuburn oil leak

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