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[T3] Stretching valve stems?

You may recall that Randy H. was asking us last week about his # 3 & 
4 cylinders which weren't firing at idle. Well, he did as much as he 
could working at home, and then drove his '71 square up here so we 
could look at it together.

The FI checked out just fine. 

The ignition was also okay.

But # 3 & 4 cylinders had zero compression.

I checked the valve adjustment and found that # 3 & 4 exhaust valves 
were tight. # 3 adjusted okay (I probably had to back it out 1 turn), 
but # 4 just adjusted out and out, until the valve spring was hitting 
the rocker rather than the valve stem.

Randy drove it home, and reported that # 4 was actually contributing 
something (I had originally disconnected the # 4 injector, but he put 
it back on the trip home.) I'm surprised at this, because it just 
seemed that there was no way for this cylinder to be building up any 

At any rate, here's the question: Do valve stems sometimes actually 
stretch before they break?

I've seen valve seats which have sunk into the head, which would mean 
a new head is in the works, but I've never seen a stretched valve. 
OTOH, the fact that VW gives the total valve length and tells you to 
check it, makes me wonder if there's actually something to this.

There's also a warning here for those of you who might be new to air 
cooled VWs. The valves in these engine require regular checking and 
adjustment. Just because you've never had to do this in anything else 
you owned doesn't mean that you can get away with that here. While I 
was under this car, I adjusted all the valves. All of them needed 
adjustment, but only the exhaust valves on the left side had gone 
completely tight. 

Randy admits that he should have checked these, but had never gotten 
around to learning the process. I agree that it's a bit intimidating 
the first few times, but it's really not rocket science; anyone can 
do it, and with minimal tools.

Jim Adney, jadney@vwtype3.org
Madison, Wisconsin, USA

List info at http://www.vwtype3.org/list | mailto:gregm@vwtype3.org

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