several newb questions/head off for first time.

[strad]

Took the head off in order to fix an oil leak from the high pressure supply to the head -- head gasket was leaking from there to the side of the block, right above the rear of the oil filter. In the process of taking the head off, got some oil and coolant into several of the head bolt holes. How do the experienced people deal with that?

I was planning on using transfer pipettes (where do you buy those?) to get most of it out, then hit it with compressed air, then chase the threads before reinstalling the head. What else should I be doing?

I think I understand how to get the block surface clean (pelican's headgasket diy). My plan for the head is to check it with a precision straightedge and feeler gauge for warping, and if it's all good clean it up. I know aluminum is very soft, so what is safe to do to it? I have a razor gasket scraper which I can drag backwards to prevent gouges, but that's not going to get it totally clean (it'll probably be smooth but will not appear brand new). What chemicals, if any, should/can I use?

[jlevie]

I just use compressed air to blow out the head bolt holes when it time to reassemble. Unless the threads in the block appear to be corroded or damaged such that you can't spin in the new head bolts with your fingers, I would not bother to chase the threads.

Any auto parts house should have products designed for assisting in gasket removal. They will make the task of removing the old gasket much easier. I us an ordinary putty knife to scrape off old gasket material. With reasonable care you aren't going to damage the head.

[learningcurve86]

i just used a linoleum razor (flat blade) and that worked really well. i can't remember the exact chemical i used though..

[strad]

Alright, story's changed a bit. I found that the straightedge needed to assess flatness to a proper standard costs half what I can get a basic head refresh for. So the head is going to a machine shop. I found a machine shop that does a lot of business and has been in business for awhile.

So it's just the block surface that I'll be cleaning. One parts guy I talked to suggested using a rolodoc (I think that's what it's called) to clean. Does that sound right or should I be using something else? It looked a bit agressive to me, but what do I know? I'm planning on cleaning the piston tops as well.

[strad]

The machine shop called after pressure checking and looking it over. No cracks (YAY!), but nine of the valve guides are bad. We're replacing all of them. Should be a nice tight head when it's finished.

[a_thomasmr23]

DON'T clean the piston tops! the crap form that will get down in your rings and tear you block a new a-hole.

If you want to clean the piston take them out of the engine

[strad]

I've been wondering about what to do there. They're not that dirty I guess. I just want to get the block surface really clean.

[Knockenwelle]

A standard razor blade, used by hand, is a great tool for this. Just keep the edge flat to the deck, and you won't scratch anything. It takes a while and a few blades; just be patient. For more stubborn deposits, I like a 1-piece long-handled scraper:

Be sure to use a lint-free rag--like a clean well-used cloth rag--with quality solvent for the final clean. Vacuum everything to pick up stray particles.

[strad]

What's a good solvent? Brake cleaner, acetone?

[twothrees]

DON'T clean the piston tops! the crap form that will get down in your rings and tear you block a new a-hole.

If you want to clean the piston take them out of the engine

He's probably right, but I cleaned mine anyway when I re-did my head. I have been running it for the past 15k with no problems. I may be good or just have gotten lucky. Be that as it may, there is a plastic wheel that you can get from autozone, et al. that attaches to an electric drill. It does a good job of getting the carbon deposits off. Do not use a wire wheel!

[strad]

:-( Closely inspected the cylinder walls. 1-4 and 6 are all perfect, crosshatching still there and all. 5 has had some trauma. I had given it a compression test about 10k miles ago, and it came out about 15 psi lower than the others (150 vs 165 iirc). It has several scored areas that I can catch a fingernail on. What I suspect happened is that the p.o. had left the spark plugs in for 55k miles, and when I removed them (at the same time as the compression test) #5 was missing part of the insulator. Actually at least one other plug was missing part of the insultor as well, but as I said, other cylinders are perfect.

My intention is to run it that way for awhile while I maybe find another M20 to build up properly. Anybody see any problems with that? I don't think the engine is burning much oil, although it was leaking a LOT from the headgasket (hence the reason for this adventure in the first place).

[jlevie]

While having a cylinder be 15psi lower that its kin is not ideal, that difference is less than the 10% limit generally accepted as cause for concern. So that engine should be okay in that regard.

[ForcedFirebird]

I've cleaned the tops of pistons on many shortblocks without problems. As mentioned above, use a vacuum cleaner and just be cautious if you do. Use acetone , ether, or brake cleaner as they will evaporate completely, then before putting the head back on, squirt a little oil on the cylinder walls since they will be bone dry, and change the oil/filter after.

[strad]

Well damn. I'm learning a lot more than I ever wanted to know about this motor. Started cleaning piston tops with brake cleaner and a rag. Got to #3 and found some FOD under the carbon. Found even more FOD on #5. It's not a life-ending amount, but still. Rather it not be there lol. All this on a motor that ran reasonably well.

[strad]

Well it is back together and running. I spun it with no fuel to prime the oil pressure, then put the fuse back in and it fired right up. After about thirty seconds, it settled down to a smooth idle. I warmed it up and bled the coolant -- that seemed to go fine. Have yet to drive it. Currently looking all over the place for the little hose clamps I just bought for the windshield washer check valve. As soon as I find them (lol), I'll be able to put the hood back on.