ALH Oil Leak Help Needed

Hi. I have a 1" spot of oil under the car every night. I jacked it up and there was oil on the engine on the passenger side of the transmission. (not on the transmission) There was oil on the axle, the dog bone, and on the hoses to the turbo, as well as the whole firewall side of the engine. I took it to the car wash and cleaned it today. (jacked it up at the car wash) I will put the URLs of the pictures I took in the next post. Any ideas as to where my leak is coming from? (Valve cover, turbo hoses?)

http://irata.com/Jetta/IMG_20200528_113245.jpg
http://irata.com/Jetta/IMG_20200528_113357.jpg
http://irata.com/Jetta/IMG_20200528_113546.jpg
http://irata.com/Jetta/IMG_20200528_113309.jpg
http://irata.com/Jetta/IMG_20200528_113456.jpg

Had something similar on my 2000 tdi ALH engine, took off valve cover, cleaned it and degreased it and put rtv gasket. It's been a while and still bone dry.

It could be a leaking EGR valve. I had the O-rings between the egr valve and intake become brittle and wasn’t sealing.
I would also pull the valve cover off and clean with a degreaser and make sure the 4 corners where the cam caps are have a dab of rtv there.
The vacuum pump O-ring/ gasket is also known to leak.

Yeah all of the things mentioned are possible. You just kinda have to go through it methodically. Start from the top and work down.
Honestly could be a couple things, it just one.

Sent from my moto g(7) power using Tapatalk

Thanks guys. My EGR has been deleted, so no leak there. The vacuum pump is in the front side of the engine, so that cannot be it. I just got some engine degreaser and jacked it up and sprayed it on all the oil that was left. I will spray it off and then rtv the valve cover. I will update this thread and let you know if that fixes it.

mrfiat said:

The vacuum pump is in the front side of the engine, so that cannot be it.

Click to expand...

The vacuum pump is located on the drivers side of the engine driven by the cam shaft , so why don’t you think it could be a/or the problem?
I had one leak and ended up on the dog bone mount.

You are right, I was wrong about the vacuum pump being the source of a possible oil leak. I looked at it and you would be able to tell from the top of the engine if it was leaking though. There was no trace of an oil leak from my vacuum pump. The leak would have to be in the rear of the vacuum pump to go down the block.

I just finished pulling the valve cover, cleaning it, and sealing it with RTV. I forgot how that top left bolt is such a pain. You have to pull the shutoff valve and the pipe or blockoff plate under the shutoff valve to get to all the bolts. My blockoff plate's bolts were a little loose and it had a rubber seal, which I think is incorrect. I had a regular gasket in stock and replaced it with that.

I think that the oil leak was mostly coming from the blockoff plate and the rest was coming from the valve cover. I will drive it tomorrow and see if I get a drip. I want to put my Panzar plate back on, but I've been waiting until I fixed this leak.

mrfiat said:

You are right, I was wrong about the vacuum pump being the source of a possible oil leak. I looked at it and you would be able to tell from the top of the engine if it was leaking though. There was no trace of an oil leak from my vacuum pump. The leak would have to be in the rear of the vacuum pump to go down the block.

I just finished pulling the valve cover, cleaning it, and sealing it with RTV. I forgot how that top left bolt is such a pain. You have to pull the shutoff valve and the pipe or blockoff plate under the shutoff valve to get to all the bolts. My blockoff plate's bolts were a little loose and it had a rubber seal, which I think is incorrect. I had a regular gasket in stock and replaced it with that.

I think that the oil leak was mostly coming from the blockoff plate and the rest was coming from the valve cover. I will drive it tomorrow and see if I get a drip. I want to put my Panzar plate back on, but I've been waiting until I fixed this leak.

Click to expand...

This is the tool on a 1/4 inch wobble drive will get those two rear bolts off the valve cover without stripping them. No need to remove anything else.

https://www.idparts.com/metalnerd-stubby-driver-mn0005-mnhb5s-p-3585.html

Thanks for the tool tip. It is $15 with shipping from IDParts and they are out of stock. I ordered this whole set of them for $26: https://www.amazon.com/SHM400-Metri...590718697&sprefix=short+allen+,aps,236&sr=8-6

Only problem is it makes the bolts difficult to get off. Remember, you need to torque those bolts correctly, otherwise, you can warp the valve cover and it'll leak.

Sent from my moto g(7) power using Tapatalk

I torqued it in a crisscross pattern in stages by feel. I did it that the way on my wagon and it hasn't leaked a drop. I know a lot of folks on here are big on using a torque wrench on every bolts, but I used to work on my older cars for years and only used a torque wrench on critical engine bolts, etc. (i.e. head bolts, wheel bolts, etc.) Never had a failure. I don't think every little bolt on the car requires a torque wrench. The valve cover just has to be evenly tightened and it shouldn't leak. Just my opinion.

Is this an OEM cylinder head on the engine?
Some of the cheaper replicas have less height to the cam blocks and it does not compress the gaskets in the arched areas.

mrfiat said:

I torqued it in a crisscross pattern in stages by feel. I did it that the way on my wagon and it hasn't leaked a drop. I know a lot of folks on here are big on using a torque wrench on every bolts, but I used to work on my older cars for years and only used a torque wrench on critical engine bolts, etc. (i.e. head bolts, wheel bolts, etc.) Never had a failure. I don't think every little bolt on the car requires a torque wrench. The valve cover just has to be evenly tightened and it shouldn't leak. Just my opinion.

Click to expand...

I agree, My statement was more reflecting the metal nerd tool that is a 1/4" drive versus the kit you posted a link to.
The nice thing about the metal nerd tool is you can use a screwdriver style driver and maintain the 7lbs torque requested on those bolts.

The other thing is if you bow the cover it never gets straight again.

Moving down the back of the block the most likely thing is the turbo supply and return lines, then turbo seals.
The unlikely thing is the bolt hole for the engine block being broken through to the oil galley, and the vacuum pump seal is more likely.

The front seals leaking would run down though the timing belt area and could blue back up and around as the rear seal could.
The oil plug would be more likely to cause an issue though.
One more thing to look at is the oil cooler. Without the engine cover on it can leak down and blow around also.

Sent from my moto g(7) power using Tapatalk

The kit I posted is 1/4" drive the same as the MetalNerd tool. I guess that makes it easier to get the wobble and extension in there. The front of the engine is as clean as a whistle, so I don't think the oil is coming from the front of the engine. I will try tightening the turbo supply lines if this fix doesn't work. If the turbo seals are leaking, then the only solution is the replace the turbo, I believe. (or live with the oil leak)



I think the leak could come from the air output of the turbo. The outlet hose was wet with oil, but most likely that came from above.


As far as I know the head is OEM. 220,000 miles on the engine and running strong. The cam looked to be a great condition.

I tighten the valve cover from the outside in in two stages. I didn't have much luck looking the for the tightening sequence on this forum. One post said to tighten from the center and work your way to the ends in a X sequence. If that is correct, then I did it wrong. I tightened it this same way on my wagon two years ago and no leaks yet. I didn't realize that the valve covers were so delicate on these cars. After 15 years, I'm still learning new things about these cars. Which is why I don't want to switch to a different car, since I know ALHs so well and have all the tools. They run forever unless someone hits you. (like what happened to my first ALH) It actually still runs great, but insurance totaled it out, so I sold it for $1000 and they are still driving it.

Wouldn't say terribly delicate. I remember the old Chevies doing the same thing. I actually think the ALH has a sturdier valve cover.
I think the reason it said to work from the inside out is so the middle doesn't buckle. I don't think it matters as much if you snug then down then tighten then up uniformly.
You probably didn't mess the cover up, not sure if you put that cover on though.
The gasket only lasts so long and unfortunately their not the replaceable kind. A previous owner could have tightened it wrong and you just get the repercussions...
Like I said before the turbo and oil lines are most likely the issue, the return line can be difficult to get tight. It's the one I usually have issues with, but, I have a braided flex line for oil supply.

Sent from my moto g(7) power using Tapatalk

Thanks, we will know in a day or two if this fixes it. I just did a search and it sounds like it is better to replace the turbo than try to replace the seals. (If it is the turbo seals) I put a VNT 17 in my wagon and it was a pain to replace, but it works great now. On my old 128 Fiats the valve cover was thick aluminum and I never had one warp.

Yes, better to replace the turbo than the oil seals. However, supply and return lines are often the culprit.
Pull the boost hose coming out of the turbo, if there's a lot of play then plan on a new one. Otherwise, plan on new oil lines if the leak doesn't stop. Generally if there's not much play in the turbo the seals should be fine.

Sent from my moto g(7) power using Tapatalk

I put a flexible oil line in when I installed my VNT17 in my wagon. It was much nicer than the hard line. If it is the oil line, then I will replace the hard line with a flexible line. That boost hose is a pain to pull as I recall. If I do get a new turbo, I might just go VNT15 again. The VNT17 on my wagon has awesome power, but the lag is annoying. The FE is less on the wagon as well due to the VNT17 and the more aggressive tune.

I have driven it two times in the past two days. It has a small drip from the bolt that holds the transmission to the engine right where the dogbone attaches. I did read on here that an oil leak right there could be from the top of the engine leaking down to there. I looked into the holes between the engine and the tranny and didn't see gobs of oil or anything. I took off the timing hole cover on the top of the tranny and everything looked dry. I know this could be from the rear main seal or the tranny input seal. Any way to be sure of where the leak is coming from?

I think my leaks on the passenger side of the engine (firewall side) are mostly fixed. There is a little bit of oil on a bolt by the turbo. I cleaned it all off yesterday and there is a little more now. (unless I missed that or it was pooled above and dripped down)

So I may have the majority of my oil leaks fixed. The rear main leaking would not be good especially since the clutch was replaced 3 years ago.

Vacuum pump leaking? The oil seal can fail and run around. You should be able to see where it comes from beings you cleaned it recently.
Honestly can't be that hard to find.
Rear main seal and input shaft seal are inside the trans housing there.
And double check the oil cooler for leaking.
Sent from my moto g(7) power using Tapatalk

I removed the vacuum pump and sure enough, I was wrong. There was a leak from the bottom corner of the pump near the firewall, right where you can't see it. I didn't have a gasket (not sure if that gasket is replaceable), so I sealed it with RTV. I took it out yesterday and this morning still had a drip by that transmission bolt near the dogbone. I cleaned all that up and will take it out again today. Hopefully that was just old oil dripping down. I do have a spare used vacuum pump that I could put on there if needed.

The good news is, no leaks from the turbo side of the engine now.

Where is the oil cooler you guys are talking about located? I didn't think the ALH had an oil cooler?

Directly below the oil filter house.

Thx. So a leak from there could go into the transmission housing and then drip out that bottom bolt?

To the left there with the hose coming off it is the oil cooler, and the right the transmission. Wind easily blows it in the engine and the point you're speaking of is the lowest point in the area. Where else could it go?

Sent from my moto g(7) power using Tapatalk

Thx. I just felt the whole oil cooler and no oil at all. I never noticed that thing before.

I've only driven it a few times due to the pandemic, but no oil spots on the floor now. Thanks guys!

RTV Silicone vs a gasket. Will either work? Looking at this other thread too which is going at the same time: http://forums.tdiclub.com/showthread.php?t=506537&highlight=valve+cover+gasket+leak Seems all of us are having this same problem now.

WantingaTDI said:

what is this RTV? I just ordered one of these from Ebay (https://www.ebay.com/itm/174066822552) but will cancel if RTV works.

Click to expand...

Rtv is gasket maker. Often doesn't work terribly long on valve covers.
The ALH has interested gasket and rtv is much cheaper, just starts leaking quicker.

Sent from my moto g(7) power using Tapatalk