ALH Vacuum Pump Oil leak

Before you ask, YES! I've done my research. Still haven't found anyone whose had a solution that worked. My vacuum pump is leaking oil all down the back of the engine and on the ground. Even has gotten on to my flywheel and makes my clutch shudder bad in the mornings (something I will eventually have to replace). So I bought brand new o-ring gaskets, replaced the one that separates the 2 halves and the one that goes b/t the head and pump. The leak is at the bottom back side of vacuum pump where it connects to the head. I meticulously cleaned everything, bolted it back together and leaked. Tried lightly sanding with fine grit to make sure gasket had a good surface to cling to. Still leaked. Tried permatex black, still leaked. Tried permatex gasket dressing, still leaked but not quite as bad. Do these pumps warp after 200k miles that makes them impossible to seal or what? Cannot figure this one out. Thanks for any tips or advice on what has worked for you.

That's also a classic spot for the valve cover to weep oil from too. What are you torquing the bolts to? Are you oiling the new gasket lightly to get it pliable? I feel your pain on this, those vac pumps aren't cheap.

Do you know if the camshaft has ever been removed, i.e. #5 bearing cap disturbed?
People often forget to put sealer under the bearing cap feet when they replace a cam.


Is this a stock OEM VW head?

TM, what size o-ring did you use between the pump halves?

Surely no one is sealing under the Cam journal cap. Never, ever heard of that until now. Anything under that Cam journal cap would affect its machined clearance with the Cam shaft journal. Yes, put some RTV in the "corners" of the cam journal cap where the contour of the valve cover meets.

Likely the vacuum pump is leaking around the base of the vacuum nipple. JB Weld is the fix there.

Lastly, I doubt an oil leak there is making it to your clutch... most likely a separate issue! And, I wouldn't be sanding on anything.

AndyBees said:

Surely no one is sealing under the Cam journal cap. Never, ever heard of that until now. Anything under that Cam journal cap would affect its machined clearance with the Cam shaft journal.
.

Click to expand...

VW does.

Don't tell me you've never noticed that when taking out a factory assembled camshaft. Don't worry...what ever does not fit gets squeezed out with torqueing. It does not prop the cap up or misalign it.

Besides, you don't seal completely under the cap...just under the tips next to the vac pump mounting surface and the outer tips of the #1 bearing cap where the cam seal is being careful to not get sealant in the oil return channels. I always see squeezed out residue there. It needs to be scraped off before reseating the cap and new sealant applied.


See the illustration 10.27 in this and #27 in the directions:

https://books.google.com/books?id=H...ealing a bearing cap VW cylinder head&f=false

TurboModified said:

............................. My vacuum pump is leaking oil all down the back of the engine and on the ground. .......................

Click to expand...

Check the mating surfaces with a straight edge. The thing will seal best with just the o-ring.
Check it's not the pump itself leaking.
Check if it's from the head or cover.

JETaah said:

Besides, you don't seal completely under the cap...just under the tips next to the vac pump mounting surface and the outer tips of the #1 bearing cap where the cam seal is being careful to not get sealant in the oil return channels. I always see squeezed out residue there. It needs to be scraped off before reseating the cap and new sealant applied.

Click to expand...

I have to second this. Didn't seal a cam cap in the wife's car, steady oil leaks occurred there. Sealed it up with a dab of rtv smaller than a grain of rice, no leaks. Did the same on my car and my father's, no cam issues.

Nevada_TDI said:

TM, what size o-ring did you use between the pump halves?

Click to expand...

I used the kit from RKXtech
https://www.rkxtech.com/collections/vacuum-pump-repair/products/vw-alh-tdi-vacuum-pump-reseal-kit

JETaah said:

Do you know if the camshaft has ever been removed, i.e. #5 bearing cap disturbed?
People often forget to put sealer under the bearing cap feet when they replace a cam.


Is this a stock OEM VW head?

Click to expand...

This is the stock head, cam has never been removed or replaced. Only TB job done twice (2nd time at 190k miles).

BobnOH said:

Check the mating surfaces with a straight edge. The thing will seal best with just the o-ring.
Check it's not the pump itself leaking.
Check if it's from the head or cover.

Click to expand...

I think your right about the straight edge. But what could have warped? Surely not the surface of the head!?!
The Valve cover has been replaced and I just put a tiny bit of RTV at the crevices/ sharp corners. The valve cover is good, I've inspected it meticulously with a light and it does have some slight weepage on the back driver side, but its nothing to complain about. I've come to expect this engine to have some slight oil leaks, its still a diesel after all. But the rate of oil coming out of the vacuum pump is more than what is acceptable.
If you can see the image below, this is where I have pin pointed the leak to.

Well my picture didn't post too well (technology )
But what I was trying to show is that the oil is leaking around the bottom of the vacuum pump under and on both sides of the tiny port/circle of the pump. from there it goes down the head on to the block on the back of engine and driver side on top of the trans. And collects on my nice clean driveway!

Here we go ---->

From your picture I'd still have to say the cam cap. It's really easy to do at least. My wife's car I never had hers off, but just a little bit of side stress made the seal leak. The torque on those bolts is really low, IIRC it's like 7 or 8ftlbs

Yeah, I've seen that brownish crud on VW heads. But, I've never put any sealant under the Cam Cap on either end of the head. Yes, as I stated previously, I do put sealant (RTV) at the "corners" where the valve cover meets the surface of the head and curvature of the Cam Cap .. no leaks. I bet my formerly owned 2000 Jetta is the most oil-free on the bottom of any at 370k miles.
---------
---------
In the pic above, notice that the top part of the sealing area is the largest part without a bolt to apply pressure... maybe someone tightened the unit way too tight... maybe it now has a hair-line crack that only leaks when the engine is hot......

Thoughts...?

Nero Morg said:

From your picture I'd still have to say the cam cap. It's really easy to do at least. My wife's car I never had hers off, but just a little bit of side stress made the seal leak. The torque on those bolts is really low, IIRC it's like 7 or 8ftlbs

Click to expand...

Cam cap nuts on ALH and AHU/1Z are 15LB-ft. M6 valve cover bolts are 7 LB-FT.

JETaah said:

Cam cap nuts on ALH and AHU/1Z are 15LB-ft. M6 valve cover bolts are 7 LB-FT.

Click to expand...

I knew there was a 7 in there somewhere. Thank you for the correction.

A week or two ago I replaced the gasket shown above in post #13, because I also had oil running down the back of the engine. Thought it was the valve cover but no. After having read all of the reports here of leaking after replacing the gasket, I decided to put a coating of Hylomar on each side of the new gasket. For those who don't know, Hylomar is a pretty unique sealant; it dries to a putty-like consistency and never gets harder. You can leave it in place and essentially re-use it. It's pretty old school but still very useful.

Anyway, the leak appears to be gone. It was really pretty bad there at the end, with many drips on the ground every time I parked. My parking lot here at work looks awful. I haven't seen a fresh drip since replacing the gasket, though, and honestly the old one didn't seem that bad. Still pliable, but a bit ovalized in cross-section.

AndyBees said:

Yeah, I've seen that brownish crud on VW heads. But, I've never put any sealant under the Cam Cap on either end of the head. Yes, as I stated previously, I do put sealant (RTV) at the "corners" where the valve cover meets the surface of the head and curvature of the Cam Cap .. no leaks. I bet my formerly owned 2000 Jetta is the most oil-free on the bottom of any at 370k miles.
---------
---------
In the pic above, notice that the top part of the sealing area is the largest part without a bolt to apply pressure... maybe someone tightened the unit way too tight... maybe it now has a hair-line crack that only leaks when the engine is hot......

Thoughts...?

Click to expand...

Hi

I know this is an old thread but I'm suffering from the start of ( or actually probably has been leaking for a bit) and oil leak around the vacuum pump.

I will be buying the reseal kit but I figure while everything is off I'd better check the area that everybody seems to be mentioning regarding the valve cover

As far as I know my cam has never been out but I'm guessing my valve cover and vacuum pump have come out probably during standard timing belt work?

My car has 440000 miles on it so I can't begrudge a little oil leaking but I would like to fix it.

Could some new pictures be posted so I can see where this small bit of RTV sealant needs to be dabbed?

I plan on ordering my vacuum pump seals on Monday and undertaking this project hopefully before too long.

Thanks in advance for any and all help

Andrew

I don't have a photo, but it is easy to see where the sealant needs to go once you have the Valve Cover off...
As I said in the post you quoted: " sealant (RTV) at the "corners" where the valve cover meets the surface of the head and curvature of the Cam Cap"

TurboModified said:

I used the kit from RKXtech
https://www.rkxtech.com/collections/vacuum-pump-repair/products/vw-alh-tdi-vacuum-pump-reseal-kit

Click to expand...

I just did this on my 2002 New Beetle - There are 2 seals, and one fits great, but the other is a simple circle that doesn't really fit the groove. This one kept popping out of the groove, and I could imagine that if you weren't careful, you could end up pinching the seal while installing it.

My solution was to take this circular o-ring and gently stretch it in my hands a few times, until it would lie in the chanel without popping out. Only then did I reinstall the parts:

Picture of the troublesome seal that was is a circle, but the groove is not a circle, and as a result you need to stretch it so it's not a wee-bit too small: