Scraping an old gnarly head gasket

I got the head for my 87 civic back from the machine shop this weekend, and was excited to get the car running this weekend.

I anticipated scraping the old head gasket material from the block to be a 10 minute job. Oops. 3 hours of scraping yielded about 4 square inches of nice clean aluminum. I did a tard-check and scraped some gasket off a block I've had sitting in the garage for a few years. Came right off beautifully in nice big chunks.

For the hell of it, I used a wire-wheel on a pneumatic rotary tool for a second or so, which yielded great results, but as the block is aluminum, I was a little worried about turning the surface into wavy-gravy.

Any thoughts? Tips? I'd like to get the sucker running this weekend.

Roloc scotch brite pads and a die grinder. Brown or blue. Brown is faster, but can remove aluminum if you're not careful. Blue takes longer but polishes it up quite nicely.

agreed. I used the brown for the stubborn old miata hg

Sweet. Any thoughts on gasket spray to "fill" any imperfections? I've already managed to scratch up a few spots trying to "dig in" too aggresively with a razor.

there is some permex stuff that's headgasket specific. I use it every time.

Are you going to laugh? "aluminum" paint is an excellent gasket prep for "craggy" surfaces.

I smell a good topic for a tech article.

Who among us wouldn't want to know the answer to this question? Most of us have tried on thing or another, but with far from scientific results.

"high heat alum paint" is used for some flat head gaskets. Yes just paint. Permatex sells a gasket remover in a spray can stuff works better then anything else i've tried. Aircraft paint remover is a far second.

44

I don't know what the machine shop did to your head, but if I got mine back and there was still gasket material on it, I would never go back there again. A decent machine shop would have hot tanked the head and made it all clean and shiny. Anytime the head is off, I just go ahead and have it resurfaced or at least checked to see how flat it is. Putting a warped head back on is asking for trouble. I use a 90 degree die grinder with a scotchbrite pad to clean gasket surfaces. That works fantastic. Many people have suggested oven cleaner will take the old gasket material right off after some soaking. Careful use of a rotary wire brush should not cause any problems.

+1 on the scotchbrite pads. They are pricey for what they are but they do the job right.

I have a couple of gasket repairs I will have to do on my FC3S (thermostat and oil pan). I'll give that Permatex spray stuff a try. I was going to use a gasket scraper and acetone nail polish remover on the old thermostat gasket, since the Hayne's manual suggested I use acetone to remove it. I have no idea how well acetone works.

JmfnB wrote: Are you going to laugh? "aluminum" paint is an excellent gasket prep for "craggy" surfaces.

That little trick is the reason so many early Porsche 964s have heads drooling oil all over the floor. Of course... Porsche in their precision german minds thought the paint was enough and decided to forgo the gasket all-together... by '91 they were installing gaskets and sans the paint too... go figure.

Have the block decked.

I don't know what the machine shop did to your head, but if I got mine back and there was still gasket material on it

Reading comprehension skills pwn you. (wink.)

Sounds like a good idea on the scotchbrite. Hadn't crossed my mind, and it'll give me an excuse to break out the "DEATH GRINDER" (the HF model with the hard to access, often stuck 'ON/OFF' switch.)

I wouldn't use power tools. Too easy to screw up.

Use a Razor Blade and/or Wood Chisel to get 95% off. Use a combination of scotchbrite (hand powered) and WD40 to get it to 98%. Ignore the rest.

Or have the block decked.

I've found that razor blades make it much easier to damage the surface than a Scotchbrite wheel on a power tool. Wood chisels? Yikes. Having the block decked requires complete disassembly, of course.

My old Caddy called for a copper dressing on the head gasket. I haven't tried it anywhere else, although the gasket itself should take care of sealing minor imperfections. That's what it's for after all...

I've been quite impressed with my ability to remove the wrong metal with a powered sander. A scotchbrite type pad an aluminum head, I bet I could accidently destroy it in under 5 minutes.

The razor blade and wood chisel have been what I always come back to, and they've always worked well for me. Sharp is the key!

16vCorey wrote: Roloc scotch brite pads and a die grinder. Brown or blue. Brown is faster, but can remove aluminum if you're not careful. Blue takes longer but polishes it up quite nicely.

These are what I always use. No way in hell would I risk gouging anything with a blade or chisel.

Only time I use a razor blade its dragged backward, and only on an iron block. NEVER on aluminum.

the permatex stuff and some hand powered scotch brite.. Maybe a putty knife for the big chunks, but that permatex stuff will get anything that a putty knife won't get easy..

Once the permatex stuff sits for a while all you will need is some shop rags and the putty knife.

Something else that helps: heat. I've used a hot air gun to cook old hardened head gaskets with pretty good results. I have also used razor blades held vertically like another poster mentioned.

And I too would never use that machine shop again. If they can't be bothered to clean off the caked on gasket as part of their repairs, what else did they not do?

The machine shop worked on the head, not the block. The block is the problem.

I use a 1" tool blank. This is a 1" X 1" X 6" bar of high speed steel, grip one end with vise grips and push it all off.

Would heat help?

Dan

Keith wrote: I've found that razor blades make it much easier to damage the surface than a Scotchbrite wheel on a power tool. Wood chisels? Yikes. Having the block decked requires complete disassembly, of course.

It's definitely possible to gouge the block with either. As long as you are patient though and keep the angle of attack right, I've had good luck with the sharp stuff.

I've also abraded a lot of aluminum in my life with powered scotchbrite (usually a scotchbrite wheel mounted to a bench grnder, but still...)

Oh... I forgot my real answer last night...

I soak the crap out of it with sea foam overnight then I use a piece of hardwood floor cut to a 45 deg point. Brazilian cherry IIRC, very hard... but not hard enough to scratch aluminium. Scotchbrite plastic soaked in sea foam with a finger (no power tool...) and then a dremel with a mild buffing wheel to get the rest if there is anything left. This goes for decarboning the piston tops as well... you can lightly tap the sharpened hardwood with a craft hammer and not damage anything.