im trying to finish up this geadgasket job on my 96 impala . i just got the heads back from the machine shop they look super clean. how clean do i need the block surface i scraped all the old gasket material off and used a few cans of part cleaner, also gone over it with several razor blades . there still seems to be a imprint of the old headgasket still there. its smooth to the touch but looks like a light film is still there. i been scrapping at it for about an hour and a half and wont go away. am i bieng to paranoid about this?

 

It's fine, just hit it with something like "Brake Clean" that doesn't leave any residue and your good.

 

Agreed.
Brake cleaner and a lint free cloth.

 

Run your fingers over the entire surface- if you feel anything it needs to come off. Touch is more reliable than sight when it comes to this.

Every once in a while I'll get a head gasket job that looks clean, only to find some old gasket hiding or pitting that needs to be filled when feeling around.

 

I'd also check and run a razor blade around where the dowel pins stick up out of the block, seems stuff likes to stick their.

 

I used real fine grit sandpaper (don't remember the exact grit, just that it was very fine), which seemed to take just about everything off. Followed that up with a couple applications of the white/green can of crc brake cleaner, the non-chlorinated stuff. Don't remember why now but I was told to use that instead of regular brake cleaner. Doing this cleaned it up beautifully, looked like a new block. I also used the brake cleaner to clean up the sealing surfaces of the heads even though they had been cleaned at a machine shop, I'm just a stickler for ultra-clean mating surfaces.

 

i have always used a 90degree die grinder and a scotch brite pad.. plugging cylinders and intake valley with rags and cardboard and tape.

 

You have to be very careful use any grit type cleaner. It can get into the rings and scratch the cyl.

 

Keep abrasives away unless after using them you thoroughly clean the entire block.

Rich

 

Do not use sandpaper period unless the block gets flushed clean. If it gets into the cylinder or the rings it could cause big problems.

Can use for lack of a better term "sandless" emery cloth or maybe crokus cloth. I have seen the stuff before and it does not use sand to "cut".

 

Yeah I used the stuff that's so fine it's hard to tell the difference between the rough side and the paper side. And I did this with shop towels overstuffed into every cylinder...and I shop vac'd the heck out of the cylinders afterward a few times...now you guys have me paranoid..lol. Never occurred to me how bad the grit could be for the motor. It was aluminum oxide sandpaper too for whatever it's worth.

 

thanks guys for the advice. i ended up using a some emory cloth to smooth stuff out. then went over with acetone and lint free cloth.... one more question for you guys . when i went to put the pass. side head on i accedentally scratched the head gasket some with the corner of the head . will that affect sealing? i scratched the gasket on the top corner closer to the lifter valley , it doesnt look like it seals anything there

 

I used a razor blade and lacquer thinner. I would not use ANY type of emery cloth or sand paper.

You must also be careful with a razor as not to gouge the surfaces of the heads or block(more dangerous on the heads). Take your time, keep the razor blade flat on the surface and be careful of the corners of the blade. That is that is the most likely thing that will cause gouges. Especially when going over a coolant or bolt hole where the corner of the blade transitions off and back onto the head surface.

If you damage of the razor's edge by hitting something too hard...change it. That damaged spot can create gouges too.