cracked head?

So I think ive pretty much figured out already that I have at the least a leaking head gasket as my cooling system is being pressurized. I overheated afew times months ago due to other cooling issues and fear this is the reason for my current issue.



Today I noticed that there are small bubbles occasionally coming out by the gasket between the exhaust mainfold and the head (on cylinder 4). That is what is making me think that the head may be cracked.


Any opinions?

Well it's either warped or cracked. Most diesels crack heads when overheated. The TDIs seem to blow head gaskets, perhaps due to warped heads. Either way it's coming off and going to the machine shop and maybe getting ditched and replaced.

ALL diesels are VERY intolerant of overheats. You can get away with it, sometimes, with a gas engine. You almost never will with a diesel.

Diesels are very intolerant of heat is an understatement. Had a piston explode on a 15 liter heavy duty engine once due to heat. Good times. Was on the dyno when it did it.

I wouldn't drive it long like that, the combustion gasses in the coolant can eventually start to rot the block out.

I had considered trying arp headbolts to see if i could remedy the situation for awhile. Is this worth a shot?

Nope. Only real way to fix it is verify flatness and replace head gasket.

iver read conflicting reports about if you should put in a hg of the same or thicker. I have a 2 hole now. Should I replace with a 2 hole or 3 hole?

Put the same HG as removed, if you are sure it was never changed before.
If you put a three hole gasket you will lower the compression ratio of the engine.

csstevej said:

Put the same HG as removed, if you are sure it was never changed before.
If you put a three hole gasket you will lower the compression ratio of the engine.

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Out of curiosity, is it enough to really make a significant difference?

I did the timing belt about 25k mi ago. That wouldn't be worth redoing, would it? Also the motor has about 200k on it now, what about the cam, lifters etc?

How's it behaving? Examine the cam (chamfer) and the visible portion of the lifters. You might proactively change them but you can do both from the top with the head on, so assuming they look ok and there's no need to send the head out then I probably wouldn't. Ditto on the timing belt.

Use the same number of holes for the gasket as the one in there. If you want to measure piston protrusion that's ok too, but assuming you have no reason to believe you've hydrolocked or had an "event" (e.g. you're not checking for bent rods) and the head hasn't been off the protrusion hasn't changed.

If the head is cracked it's junk. Don't buy a Chineesium one; I'd find a usable one off a pick-n-pull or similar and either use it as it sits or send it out and have it reworked (e.g. new guides, etc) and install that.

ajoncar said:

I did the timing belt about 25k mi ago. That wouldn't be worth redoing, would it? Also the motor has about 200k on it now, what about the cam, lifters etc?

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If you are going to go thru the effort/expense of getting the head fixed/replaced and plan to keep the car for an extended time or the long haul I would do cam and lifters. They are relatively inexpensive and don't generally last forever anyways.

Nero Morg said:

Out of curiosity, is it enough to really make a significant difference?

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Nero, from what I’ve read it does, I don’t have the actual numbers, I’ve seen them float around on various threads.
Hopefully someone more knowledgeable then me can post that info.

Also If the head is cracked don’t scrap it, contact Franko6 on here, he can do incredible things with heads that are considered trash, he useally has exchange ones, you give him yours and if salvageable you pay for an exchanged on the has been gone over and almost be like new.

There is a measurement to make to determine hg thickness. No need for stronger bolts.
But I think you need to go a bit further assessing the potential block damage.
Timing belt, it's good practice to at least install a new tensioner.

BobnOH said:

There is a measurement to make to determine hg thickness. No need for stronger bolts.
But I think you need to go a bit further assessing the potential block damage.
Timing belt, it's good practice to at least install a new tensioner.

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I second this. But still keep the belt as 25k miles old.

I had bubbles coming out of the exhaust manifold as well on 1 and 4, replaced the valve stem seals and that stopped. There was oil running down the back of the block under those ports.

So you were getting h2o/coolant coming through your valve stem seals? were you loosing a significant amount of water due to that, because I am. My coolant light comes on (overflow tank empty) after about 35 miles of mountain driving. Did you suspect a head gasket in your case? Im planning on pulling the head in afew hours but this is making me reconsider...