Useable Head??

swankyrabbit · Post by **swankyrabbit** » Sat Feb 16, 2008 1:45 am

I cleaned up my head on my '80 bunny running a 1.6na and I came across a crack that might be to large (see pics). Another awfully odd thing is the 4 punch marks around the valves, does anyone know why someone would add those?

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woodrat · Post by **woodrat** » Sat Feb 16, 2008 2:09 am

I'm guessing those punch marks are to keep the valve seat from coming loose.

82vdub · Post by **82vdub** » Sat Feb 16, 2008 10:16 am

woodrat wrote:I'm guessing those punch marks are to keep the valve seat from coming loose.

X2

libbybapa · Post by **libbybapa** » Sat Feb 16, 2008 10:24 am

Probably someone who was used to working on Type-4 motors...

Andrew

woodrat · Post by **woodrat** » Sat Feb 16, 2008 11:06 am

yeah, no kidding. Many years ago I bought a rebuilt bus engine off of a reliable guy, installed it in a friend's bus and it dropped a valve seat less than a month later. Heads had been rebuilt by a reputable shop, but that was right around the time that the castings on those things were starting to drop seats everywhere. That month there was an article in hot VWs or something like that about dropped seats and peening them in.

CoolAirVw · Post by **CoolAirVw** » Sat Feb 16, 2008 6:17 pm

Maybe you should put some punch marks around your Pre-combustion chambers. The one in the pic looks like it may have some clearance between the PC chamber and the head. (maybe its just the picture though.)

Oh, and I guess your wondering if the crack is too large? Answer, I dont know. But since no one else seemed to respond to it maybe they'll see what I wrote and answer.

I would at least pull the valves out and look for cracks between intake and exhaust chamber. I think I would dremel the crack out a little with a cutting wheel so that there's less chance of a peice "falling" off and crashing your valves.

coke · Post by **coke** » Sat Feb 16, 2008 8:03 pm

Jack told me the cracks are fine as long as you can't get your thumb nail in the crack.

However, I had an 84 that had these cracks and I'm quite positive they violated this rule, and I ran it for another 150k miles like that.

ahistand · Post by **ahistand** » Sat Feb 16, 2008 9:01 pm

A little off topic, but someone commented on pre-chambers being too loose. Well i'm rebuilding a TD head and one of the pre chambers will come out quite easily....almost fall out. I never gave it a second thought in terms of it being dangerous....wouldn't the head gasket keep the pre chambers in place? I know at least part of the gasket covers the pre chambers. Whats the concern with that? Surely they dont need to be super tight for compression reasons, seeing as how they have a hole in the middle which makes the pre chamber volume part of the combustion chamber, effectively. Has someone seen one drop out and cause damage?

Clue me in please, because this is the second time I have seen someone raise an eyebrow to a loose pre-chamber.

Quantum-man · Post by **Quantum-man** » Sat Feb 16, 2008 9:17 pm

ahistand wrote:A little off topic, but someone commented on pre-chambers being too loose. Well i'm rebuilding a TD head and one of the pre chambers will come out quite easily....almost fall out. I never gave it a second thought in terms of it being dangerous....wouldn't the head gasket keep the pre chambers in place? I know at least part of the gasket covers the pre chambers. Whats the concern with that? Surely they dont need to be super tight for compression reasons, seeing as how they have a hole in the middle which makes the pre chamber volume part of the combustion chamber, effectively. Has someone seen one drop out and cause damage?

Clue me in please, because this is the second time I have seen someone raise an eyebrow to a loose pre-chamber.

Could they be blown out by off TDC detonation?

libbybapa · Post by **libbybapa** » Sat Feb 16, 2008 9:34 pm

In the last 4 or 5 years I've seen pictures of 4 different engines that had a pre-chamber fall into the cylinder... Certainly I've heard of Quite a few more engines in that time being destroyed by someone not installing the timing belt cover and yet have still heard people promote not reinstalling the timing belt covers... Most likely you won't have a problem in either case. Then again you can easily make sure you won't have a problem in either case.

Do you feel lucky, punk? Do you?

Andrew

mattbondy · Post by **mattbondy** » Sat Feb 16, 2008 9:42 pm

viewtopic.php?t=7799

Recent post with what could have been a loose prechamber.

woodrat · Post by **woodrat** » Sat Feb 16, 2008 9:43 pm

It always gives me the willies when I see rigs running with a naked timing belt...

not only could you kill the car, you could do some pretty major damage to yourself, too.

surfcam · Post by **surfcam** » Sun Feb 17, 2008 2:03 pm

I believe when the first rabbits came out (gasser). They had gaps in the guard. My dad phoned me to come and get him one night because his rabbit quit. We looked under the hood and we seen some white flakes and broken belt. It seemed like the tell tail sighs of a rock. People in a house where he broke down invited him in for coffee and sandwiches. He was telling me about the great time he had all the way home. It wouldn't had been so great if he had owned a diesel.

Former VWDieselParts.com Forum

Useable Head??

Useable Head??

pre-chambers

Re: pre-chambers