Former VWDieselParts.com Forum

A very close friend of mine who has been in the automotive repair business most of his life (he's in his late 70s/early 80s now) got me interested in the VW Diesels in my mid to late teenage years. One of the things he told me early on was to avoid the 11mm blocks altogether. He made his career as a diesel engine mechanic and he was very skilled. He told me if someone gave him one in running condition, he would run it until the block cracked or it broke and that would be it, and then he'd replace it with a 12mm block.

My first was an 84 Jetta that I bought with 296k miles and a blown head gasket. He put a new headgasket in, and reused the old "stretch bolts" going only a 1/4 turn on each tightening sequence instead of the prescribed half. I never had a single issue with that engine with the exception of the IP main shaft seal leaking, which I had him replace for me. The car ran until 430k miles when it blew the head gasket again under the next door neighbors ownership.

Given your struggles, I'm leaning towards a cracked block or possibly even a cracked head causing your problems. I'd seek out a 12mm block to replace it with. They seem to be much sturdier and less prone to the issues of the earlier iterations.

Thanks. Seems to be the general consensus about the early blocks. Haven't spent
much on this engine other than external fixes, I consider that lucky.
Trying to find a good engine someone has laying around isn't going easy tho, as people
have largely forgotten about the old IDI's
I found 1 rebuilt long block (bored .040), 800 miles away .
And then there are the pulled engines from qualitgermanautoparts
Shipping is steep

It would be great if you could plug the oil supply hole coming from the block
with the head off.
Then spin the oil pump and see if/where it's getting into the coolant passages.

I don't think any other bolt hole could leak oil into the coolant.
There's only one that is under pressure.

I still suspect the coolant reservoir cap.

I plugged the oil feed hole off with a 6x1.0 bolt w/ some thin poly fuel tubing slipped over it for a perfect seal.
Spun the oil pump for a minute or so
Left coolant in the block to see if more oil floats to the top. Kinda hard to tell but doesn't seem like anything different
than when it just sits.
The 11mm bolt hole next to the oil feed looks fine. No oil getting in it, no visible cracks anywhere.

I have a straight edge coming today for checking flatness of the block.

Block says GERMANY on it

I'm wonder what the odds are the head could be the problem.
It was skimmed .015 in the past by the PO

It could be the head. If it was skimmed, it means the PO suspected issues, or the shop that skimmed it did. I am always 100% suspect of any work previous owners do. While these engines are inherently simple to work on, there are a lot of bad mechanics out there that make, and excuse my french, piss poor decisions when it comes to fixing these engines.

The early 11mm blocks remind me of the early GM 5.7 diesel engines. A lot of people thought that GM simply turned the 350 gas block into a diesel, but that isn't the case either. They just had some really bad design flaws from the factory (the early ones, my understanding is the later ones corrected some of these inherent deficiencies.)

If your head was skimmed, that's a good place to start.

I think that's the only bolt hole that's surrounded by oil.
Especially one that has oil under pressure.

Talked to the machine shop guy, he was nice enough to ponder this
thing over the phone for a while. With no visual indications, (and no water in the oil)
the cause seems to rather odd to him.
Tomorrow I'm gonna try a soapy water test while spinning the oil pump.
Wish I had a working head (to put on there).
This old head is pretty beat up, lol.

Well, I ditched that engine and got a 12mm 1.6 that was already rebuilt to replace it.
It may just have a hidden crack in the head and the block is fine. The valve shims in that one were
all really thin. Even with studs the HG never did seal well.