shallow headbolt treaded hole ??

on my 1.6 1985 vw diesel (in a 92 shadow) I seem to have a minute amount of oil coming out between the head and the block suggesting head gasket issues.
it it not even enough oil to run down the block but rather be safe than sorry .
the engine was a re build with a new head about 2 years ago, the head was loose on the block when I got it . when I torqued the head (in sequence and to correct torque ) I noticed one of the head bolts not taking the same amount of revolutions and appeared to "bottom out" in the block .
I chopped about 12 mm off the bolt and secured to spec.

now : if I replace the head gasket(and install new head bolts) it is likely I will be running into the same problem.

am I better off to shim up the bolt(12mm) with washers rather than cutting the bolt?? any suggestions?/

thanks

How long were the stock bolts? How long were the ones you put I? Which one bottomed out early?

I don't know that head or block, but if it's like the 1Z, each hole is blind, that is they don't intersect coolant or oil gallies in the threaded region. However, there are two holes, one for coolant and one for oil that the shank passes through so when the old bolts are removed, they fill up a bit. When torquing down a bolt you have to give it some time for the fluid to make it past the threads and normalize pressure so the bolt can be torqued all of the way.

12 mm is a big difference, too big to ignore without confirming the passages and holes are uniform or free or debris.

The 1.6D / TD take the same head bolts as the TDI from about '82 up, there shouldn't be any interference in there at all.

I can't imagine what might be in there that was obstructing the one bolt but I would think it should be checked out. Maybe it bottomed because there was a bolt accidentally dropped in there at some point?

Steve

In that case, the stock bolt length is 115mm and either 110mm or 120mm bolts should fit. M12 that is.

the hole that appears shallow is near cyl #3 ,toward the front of the engine. probing the hole did not show anything loose or foreign.

how tight and how fast did you try and torque it? When it's bleeding out the oil or coolant it can feel like you bottom out if you go too fast.

Digital Corpus said:

how tight and how fast did you try and torque it? When it's bleeding out the oil or coolant it can feel like you bottom out if you go too fast.

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I have not tried to RE torque it but for the price of a valve cover gasket it is worth a try . 66 ft/lb?

IDI is different than TDI, sorry. That and my lubricated threads makes it a different matter entirely.

I'm confused about the fluid in the holes. Don't you drain the coolant, prior to pulling the head? Otherwise, you'll have a mess when pulling the head.

I'd think the oil would drain back down to the pan.

Regardless, I always chase the threads with a modified bolt, then always blow the debris out.

-Todd

You'll never get everything out of the holes and even with draining the head of oil and coolant, some stays behind. The holes are blind meaning they don't drain anywhere so paper towels etc are needed to remove the oil/coolant.

The head bolt in front - between cyls 3 & 4 , just happens to have an oil feed / supply hole next to it. A retorque might patch you up.

As for the original problem with having to trim a bolt - that is not normal at all. If you end up pulling the head eventually and replacing the head gasket , measure the depth of that hole and compare to others.

If you plan on replacing the valve cover gasket - order a 1-piece rubber gasket for a 95 Jetta Gasser . Its re-usable .. and .. 1 piece versus 3 .
Then go to hardware and get new studs that are strait . The originals will be shouldered and won't jive with the metal eyelets made into the gasket.
The studs i get locally have allen head at top.

Digital Corpus said:

You'll never get everything out of the holes and even with draining the head of oil and coolant, some stays behind. The holes are blind meaning they don't drain anywhere so paper towels etc are needed to remove the oil/coolant.

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That's where blowing the holes out with the air line comes in. I run my makeshift thread chaser a few times with lubricant, then blow the excess out with the air line. Spray carb cleaner or brake clean into each hole then blow them out again. There shouldn't be anything in the hole, once I'm finished.

If the OP needed to trim a bolt or torque slowly, that means there's a significant amount of fluid in that hole. I don't consider that to be a proper installation.

-Todd

Baron VonZeppelin said:

The head bolt in front - between cyls 3 & 4 , just happens to have an oil feed / supply hole next to it. A retorque might patch you up.

As for the original problem with having to trim a bolt - that is not normal at all. If you end up pulling the head eventually and replacing the head gasket , measure the depth of that hole and compare to others.

If you plan on replacing the valve cover gasket - order a 1-piece rubber gasket for a 95 Jetta Gasser . Its re-usable .. and .. 1 piece versus 3 .
Then go to hardware and get new studs that are strait . The originals will be shouldered and won't jive with the metal eyelets made into the gasket.
The studs i get locally have allen head at top.

Click to expand...

yes , I did just that and lets see if it stops the weeping. measuring the depth is also on the schedule is the head has to come off . if the hole just has not been drilled deep enough , my options are limited .

If the wasn't drilled deep enough, I'm sure yours wasn't the only one and Google would tell you.

Digital Corpus said:

If the wasn't drilled deep enough, I'm sure yours wasn't the only one and Google would tell you.

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Yes, I'm sure something would be mentioned somewhere online, but I can't imagine that it would have ever gotten out of the factory like that originally.

Wonder what the chances are that a head bolt broke off a chunk in there?

Steve

Also worth mentioning, it's very common for the IDI engines to seep a little oil between cylinders 3 and 4. The high pressure feed is there to the head. Unless it's a LOT of oil I wouldn't worry about it too much, it's not a sign of anything combustion related happening.

The "one short bolt" thing is definitely not right. What did you use to chase out the holes? The last 1.6 I did a head gasket on had a couple of holes that really had a lot of goop that needed to be cleaned out.