Good day Melissa,

Your mechanic is right, it' a crack or a stripped plug thread and/or both!
Don't panic, no here is what you can do since you have some time.

You should remove the left cooling tin, the big one that cover the heads (#3
&#4), not very dificult unless a few screws a rusted there. The 2 most
dificult screw are the one in front, you need to reach them from underneet
the van. (unless the vanagon is different from my Bus), anyway, remove this
 one so you can have a close look at the left head.

Now have a look at that thread, take a flashlight and look at/in the thread,
is there still some thread over there? Insert the plug just a few threads
deap! is it very loose? Do you see aluminum particle near the plug hole?
Compare thread with cyl #4? removing a head is very simple on air-cooled,
the head is not the problem, it's the dam* heater box that are the real problem.

You won't see any carck from outside but the good news is if you have a
crack BETWEEN one valve and the plug hole it CAN be fix, if the crack is
elsewhere, you will need a new/rebuilt head, sadly you cannot change one
head only, both have to be rebuilt/change to keep the engine compression even.

Now lets asume that the head is out and you have a crack where you don't
want one, you will need to find a good core (head) or buy a rebuilt one, now
here is the problem; the new/rebuilt head will have been "Machined", in
other words, some metal as been remove to get the matting suface flat and
even, your good head (the right one) as more metal left than the new rebuilt
one, not good! (we call that "deck high"), this is where the engine make is
"Compression", so in simple words, if one head as more metal than the other
one, the compression ratio won't be the same each side. This is not the only
problem, of course when you have a new head you have new valves, that mean
high compression, the other head as old valve!!!! you follow me. one side of
the engine will produce more power than the other side...Very bad, this
would result in an uneven engine, shaking and premature wear of other
internal parts. In conclusion, both heads as to be the same! This is only if
the crack cannot be repair!!!

If the crack can be welded, you nly need a new insert for the plug thread
and a good weld.

Just so you know, i just did mine on my 73 bus's, the total cost of 2
rebuilt head including new..everything and "WELDED SEAT", yeas welded seats
was about 455$ CAD(about 300USD).
http://www.desert2002.com/heads.htm

Good luck, Ben
http://www3.sympatico.ca/huotx/engine1.htm

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I had to cut short a road trip yesterday because my 81 Vanagon has ejected
the #3 spark plug twice during my travels, which I replaced by the side of
the road with a new one each time. I was able to tighten it down, or at
least so I thought. I called my mechanic from the road after the second
occurrence and he assured me I could make it home safely and I did.

Now that I am home, I am looking for wisdom from the list. My mechanic says
either I have stripped threads or a cracked head (horrors!), which is
heating up, expanding and letting go of the spark plug. I won't be taking
the bus in until Monday, so any other thoughts, wisdom, advice and anything
you all think I can check out on my own will be appreciated. I have a few
days off and time to tinker since I am no longer camping under the watchful
eye of Mt. Shasta :-(

Thanks! -- Melissa Mourkas 81 Westy Basic Camper