Stubborn head gasket removal

[MadeThatMyself]

Any tips for removing stuck head gasket? These pieces are stuck on there good. I tried some degreaser with a plastic safety scraper to no avail. Just read to try paint stripper or maybe try some heat?

It also looks like there are small impressions in the mating surfaces from the old head gasket. Should I be concerned?

 

[Jim]

I use paint stripper. Let it soften the gasket remnants, scrape off. Reapply stripper and repeat until done..

 

[5twins]

Not paint thinner, paint stripper. "Paint" a coat on, let it soak in and soften the gasket for 10 minutes or so, gently scrape off the softened portion. It often takes several applications to get it all off, but this will do the trick without risking damage to the sealing surfaces from over-aggressive scraping.

 

[Jim]

try paint thinner and maybe add some heat?

Thinners gives off an explosive vapor. Heat sources can (and generally do) provide an ignition source. That's a combination that calls for extreme caution.

 

[5twins]

Another difficult to remove gasket you're going to encounter are the ones on the point/advance housings. Yamaha installed them with gasket sealer. Same technique applies - start by "painting" them with stripper and let them soak .....

..... then gently scrape off the softened portions .....

In this case, a 2nd application pretty much released the rest of it. A few dabs on the remaining little spots and it was a done deal .....

Paint stripper is also a good way to de-carbonize the pistons and combustion chamber. Basically it will just melt most of the carbon away in the course of several applications .....

I finish the job with some chrome cleaner and then, of course, a good scrubbing with hot, soapy water .....

 

[MadeThatMyself]

Sorry!!! Definitely meant to type stripper (not thinner)... I edited the original post to keep from spreading bad information.

 

[xjwmx]

Not just any stripper, esp. not the orange kind, but the kind that is very aggressive. It's like a translucent thin gel that will burn your hands. Usually comes in a rectangular metal can. Wally has some.
That pattern you see at the back, I got that off as much as I could with the stripper. It is stubborn and I'm not sure what it is, maybe some sealer, but I realized it wasn't really raised so just left the remnants there. I used good old nos gaskets they were selling on ebay for awhile for about $11 a set, same thickness as original. Saw very vehement advice/instruction to not use any sealer, and haven't had any problem from that. Also didn't use sealer on the rockers cap up top and have no leak there either. ymmv

 

[MadeThatMyself]

I assume we are talking about the "aircraft" paint strippers. I had some of that and it seems to be working- slowly. The plastic scraper didn't do much, so I am carefully using a razor blade...

 

[5twins]

If you place an order from MikesXS in the future, get one of these, it's a wonderful tool. It's one of the few things they sell that I can highly recommend .....

https://www.mikesxs.net/yamaha-xs650-scraper-knife-15mm.html

Besides this, I have a couple old small knives I use. Both had their tips broken off but sharpening that end allows them to be used as a push type scraper along with the obvious "carving" technique a knife will offer .....

 

[xjwmx]

I assume we are talking about the "aircraft" paint strippers. I had some of that and it seems to be working- slowly. The plastic scraper didn't do much, so I am carefully using a razor blade...

I think what is called "aircraft" on here is the same, like the stuff in 5T's pic. Let the stripper sit on thick for an hour or longer to do its thing before you scrape. I ended up combining that with a razor blade in a scraper holder. Plastic scraper was pretty ineffectual. Careful not to gouge it, but if you think about it a little gouge that doesn't run very far and that's just a trough isn't going to affect anything. You don't want to make a surface that's uneven though.

 

[5twins]

I've tried several different brands over the years. Some work slightly better than others but the difference isn't night and day. All take some time and several applications. I haven't found a "silver bullet" stripper yet, lol.

 

[canuck1969]

This was my go to on my rebuild for stripping paint and gaskets. No issues on either front.

 

[Jim]

This stuff works good too....

 

[canuck1969]

Permatex also makes a gasket stripper. Works very well but hard to control the spray if the cases are painted. You have to mask everything off and even then it can get under the tape. It will take the paint right off. Brush on works the best.