Quote:
Originally Posted by Mr Basil
I am all ready to install the new valve guide that was supposed to arrive yesterday. My exhaust guide failed on a cylinder that fouled plugs. When I was replacing the seal the guide lifted right out. My repair guide says to heat the head up to 174-194 degrees and cool the new slightly oversize guide with liquid air or dry ice. I'll be heating mine in a little makeshift hot air oven and cooling it in a bag surrounded by salted ice. If I didn't already have the head off for another problem, I would be tempted to run the engine and have a cold oversize valve guide ready to put in. It's more time consuming than I expected removing the head, because you have so much stuff to clean and keep clean. That's assuming your valve is too loose like mine. If not, I know that some shops don't bother with heating and cooling but use a little air powered "rattling" device. It seems like in the long run that could do more harm than good, but you can think about it if you're doing a bunch of cleaning... 
I have read some people think there should be no loosness between the guide and the valve stem but it would seize if there wasn't a tiny bit of room around those fat stems.
Hope you have an easy time of it and don't have to remove the head -it can become a can of worms!
Basil |
I watched a ham fisted mechanic ruin two VW air cooled heads using a "air chisel" valve guide installer. He cracked both heads, because he failed to heat the head and cool the guide. Then he blamed it on "mislabled" valve guides.
The machinst that I used to use years ago, specialized in Harley Davidson drag bikes. He would turn the oversized valve guide down on the lathe until he got it fit the way he liked it. It took him forever, but the racers could ill afford a blown motor at high speeds.