Rep Power: 0

Hey,
Doing a head gasket job for my friend who doesn't do too much mechanical work. Got the head off today, found that gasket was definitely blown through. Also, there are deposits on the head where the coolant that flows around the cylinders touches. The deposits scratch off with a knife.
Is it worth getting a rebuilt head or sending this head to a machine shop?
I tech heavy equipment, so generally replace anything I don't trust, but he'd like to save some money- and I am gauging how much I can trust re-useing this head.

Thanks for any info,
Chad

 
Rep Power: 216

There is a term for the process to flatten and clean up the surface of the head, but I can't remember it. If the space between the head and a straightedge is still within spec(not sure what it is for 7th gens), you should be fine. If it's warped or the space is outta spec though, you'd be better off with a new one.

 
Rep Power: 312

DO NOT scratch the surface of the head with a knife. (I'm pretty sure that's what you were talking about where the cylinder touches) Especially where the head meets the block. If you marr the surface deep they won't be able to correct it at a machine shop and the head and block won't meet correctly any more and you will blow gaskets like crazy. Take it to a shop and get it checked for trueness and cleaned up. There are special white plastic die grinder bits you can use and it's the only way to clean the head up. I used 1500 grit sandpaper on a 2x4 but even that I can't recommend. 1/4 of a mm scratch in the surface is enough to pop a brand new head gasket. Get it sent out, don't bother getting a rebuilt. The head is probably okay.

 
Rep Power: 811

a machine shop can make it good as new (test valve seals and compression, mill the bottom mating surface if its not perfectly straight, hot tank it to clean all the residue, add assembly grease, etc). almost always the head can be milled and reused at least once when changing the headgasket. the mating surface of the head was surprisingly not very smooth from the factory. a new head costs over $1k and is no way needed. used heads go for $150-200 on ebay and should be checked at the machine shop anyway. just reuse what you have.