Whats the best way to clean the head gasket surface of the block for new head gaskets without having it machined? Can you get away with not machining the block or does it absolutely have to be done every time the head gaskets are changed? My block is straight so I'm hoping I don't need it machined... Thanks

 

Just because you take the heads off doesn't mean you have to machine the heads. The way to measure them is with a true bar and a set of feeler gauges. If the heads aren't true then you should machine them.

When cleaning the deck and heads for assembly make sure you chase the threads with a tap. Also, you should make sure the head bolts are clean and lubricated. I cleaned the deck and head machined surfaces with denatured alcohol before assembly.

 

I've been cleaning the surface with lacquer thinner. I can still see the outline of the old head gasket on the block, is that ok? My engine shop guy said to scrape the block with a new sharp razor to remove anything leftover from the old head gasket. I tried this but there are still some very thin pieces of old head gasket stuck to the block that the razor won't take off. Does all this residue have to come off? If so any suggestions on how to get it off? Thanks

 

Green scotchbright pads should do the trick. Rub vigorously.

 

Make sure you get it COMPLETELY clean before installing the new head gaskets and heads.

 

Yes, it needs to come off. Even though it might look true, the slightest bump or imperfection can create a sealing problem.

Easiest way is to use "Scotchlok" Scotchbrite cookies on a die grinder or good electric drill. Use the lightest grit that will take the crud off. You can get a special mandrel that the scotchlok cookie threads into.

 

ok I'll try that...thanks!

 

What ever you decide to use, if abrasive materials are in the scotch pad or some type zip wheel or anything of that nature. Be very, very, very, careful the abrasives don't end up in oil holes or down in the cylinders. A friend of mine told me (he works for an extended warranty company) that many professional mechanic shops have been using those abrasive wheels/zip wheels etc and what has been happening is the dust or abrasive residue left behind has been finding its way into the oil and clogging up oil pumps or worse yet finding its way to the bearings and spinning the bearings. Apparently many shops have had to replace engines due to this. Just a word of caution. Please don't take offense as you may already know this.

 

yeah you are completely right. I was thinking the same thing so I decided to do it by hand, that way I can control the pad much better. I also used some very fine razor blades and this second time around I was able to remove a lot more of the stuff that was stuck on. I think patience is by far the most important tool to have for this... but anyways thanks for the help!

 

The place that did my engine had numerous warnings on the paperwork about using Scotchbrite. They are a production shop and rebuild thousands of engines a year so they have some experience. The guy that brought the engine back also told me in very forceful terms not to use Scotchbrite under any circumstances or it will void the warranty. He told me years ago they and others had a lot of problems with customer finished engines until the engine rebuilders association had research done and found the culprit.

Allan

 

Did they give a reason why? It didn't seem to work all that very well anyways, I used the razor blades mostly and I made sure no threads or whatever from the pad got into the block The trick with the razor blades seems to be to always use brand new ones and not to use any single one for too long. I asked my engine guy and he said pads can create low spots but there is no way I used the pad long enough to make a low spot...

 

Mr gasket spray on gasket remover, let set as directed and scrape of with a professional grade scraper has always worked well for me

 

I would not use the scotchbrite with an assembled motor. If its just a bare block the scotchbrite is fine since you can clean it all out. If its together a new razor blade and laquer thinner used sparingly works well.

 

Yeah,elbow grease and a nice sharp scraper will work great. Just be careful when scraping old gaskets off aluminum!

 

I know this is an older thread, but my cylinder heads just arrived from the machine shop Friday, and this thread has been by far the most helpful information I have seen for a neophyte like myself. The folks at the machine shop gave me good instructions on cleaning the cylinder head mating surface of the block, but this clarified everything nicely for me.

 

another vote for lacquer thinner and a single edge razor blade in a holder. Please don't use abrasive pads and a grinder or drill. Not only will you get the cr## spread around, the surface will end up rippled and uneven instead of dead flat.

 

I have always covered the valley and then clean the head surface and the threads out. I use a air compressor to blow out holes and the dust off.
Gene

 

If you want one of the best gasket/deck surface cleaning tools in existence, go to www.goodson.com. They have a super scraper, 2" or 1 1/4", that is very nice to use. I have both of them and clean aluminum block deck surfaces pretty often on the LSX GM motors. Part # SS-4U2 for the 2", SS-4U for the 1 1/4". You can do iron blocks as well, great tool to have!

 

Hmm, I've been working away at this for about an hour now, and the gasket material is coming off nicely, but there is what looks like a black gasket template on the surface. It's not a gasket-like material, it more appears to be a paint or die. the razor won't touch it. any thoughts? This is an original, never machined block.

Thanks!

 

Even when clean you might have a little bit of color where the gasket was. As long and its smooth you are fine.