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Valve cover leak on ALH engine

 
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Steffen G
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Post14-04-2025, 20:54    Subject: Valve cover leak on ALH engine Quote

Hello!

I took my old Golf to the TÜV (technical inspection agency) last week.

Okay, so it's a 1997 model, one of the first Volkswagen Golf 4s.
I have the ALH engine with a 1.9L displacement, 90 horsepower, and a distributor injection pump.

So far, the issues with the defects have been relatively minor.
But I need to find a way to seal the valve cover gasket.
Something is leaking.
I also need to go for a follow-up appointment.

As far as I understand, they are not available individually.
but I would probably have to buy a new valve cover.
If I understand correctly, the gasket is either glued in place or vulcanized.

If you search a little more thoroughly,
You can also buy the seals individually.

Okay, I'm just going to ask a simple question.
Has anyone had any experience with this?
I've never done anything like that myself... simply because it's never been necessary. Even where we had the workshop in the family, it was never necessary to do anything about it.

What's the best and most reliable way to seal it?
Grüße, Steffen!

Golf 4 TDI,
T4 Doka-Pritsche, paar Oldtimer


Last edited on 14-04-2025, 20:56, edited 2 times in total.
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Post14-04-2025, 21:13    Subject: Valve cover leak on ALH engine Quote

Hello Steffen,

The cylinder head cover for the ALH engine is actually very good.
If the hood doesn't have any cracks or is warped (due to unevenly tightened screws), I would recommend removing it, cleaning it, degreasing it, and reattaching it with a suitable sealant.

Tighten the screws in multiple steps, in a criss-cross pattern. I don't remember if there was some kind of rubber half-moon shape on the camshaft sprocket side, or if I'm confusing something. If there was, it's best to replace it.

Let's also check if the leak is actually coming from the hood and that there are no leaks in the oil feed line or the oil separator/hose leading to the oil separator.

Best regards, Rainer.
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Last edited on 14-04-2025, 21:15, edited 2 times in total.
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Steffen G
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Post15-04-2025, 21:30    Subject: Valve cover leak on ALH engine Quote

Hi!

Well, the engine is leaking everywhere.
But that's all minor.

There were no oil stains, so the car wasn't leaking.

The ventilation area is slightly oily, and the charge air hoses are...
Basically everywhere, but only in very small amounts.

"Well, that was just a new, young inspector. He used a light to look at the engine block and saw that there was some oil on it."

The old inspectors would have only checked to see if there were any oil droplets on the lower panel (there weren't), and then they would have been satisfied.

And yes, behind the VDD, in a depression, something also accumulated.
It can only be caused by that.
What has accumulated over the past 15 years.
I've never had the lid off before either.

I've already cleaned the engine, and I've even let it run for half an hour.
Okay, yes, if you look closely, there is something there, but it's really, absolutely minimal. So, you can kind of see it starting to emerge now.
"There's a leak, but it doesn't get any worse."

Well, I still have 3 weeks.
I'll take the lid off and have a look.
I'm even more interested in what the camshaft and other components look like.

I will report...
Grüße, Steffen!

Golf 4 TDI,
T4 Doka-Pritsche, paar Oldtimer
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Post16-04-2025, 14:35    Subject: Valve cover leak on ALH engine Quote

If I remember correctly, on my A3 with AHF (the valve cover/oil separator should be the same as on the ALH), the round oil separator once became clogged and leaked. It's possible that a seam has come loose on yours as well, causing oil mist.
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Post16-04-2025, 17:57    Subject: Valve cover leak on ALH engine Quote

Remove the valve cover, verschandeln the sealing surfaces (make sure they are grease-free!), apply a thin layer of sealant like Dirko HT to the surfaces, and you're done.
Before use, allow to dry completely. See the enclosed instructions.
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