i am replacing my head gasket on my '87 740 turbo. I've sent out the head to get a valve job done and a resurface. i read about that you have to be very careful to clean the engine block surface where the head gasket goes.
My question is, can i use a fine rotating wire brush to clean the surface? I would use my electrical drill to do the job, and use lacquer thinner to clean up. Or shall i still go for the razor blade as described in FAQ. Basically, what's the best and easiest way to clean the surface.
Also, when i removed the head, a lot of carbon deposit fell into the cylinders. can i "just" vacuum it out with a vacuum cleaner?
thanks!

A razor blade (single sided) works great. Scrape, don't slice. Keep the angle low (30 degrees UP from FLAT is good to start). High angles make razor blades skip.

If there are trouble spots, some 00 or maybe 0 steel wool might work, but... there are lots of steel hairs floating around. A softish scotch brite pad might work too.

Whatever you do, I would thoroughly oil the bores and piston tops before scraping anything. The oil will capture the small scraps when they touch the oil, and cleanup is easy.

Good Luck!

I'm seconding John Sargent's method, and would avoid using power tools. I use an old woodworking chisel that I resharpen on the bench grinder as my scraper, and plug ALL the holes in the block deck with bits of rag or paper towel. I also put oily - almost to the point of being wet - rags in the bores with the pistons halfway down. After the scraping, the shopvac goes into action all around the deck after pulling the rags, as well as on the piston tops.

Turn over the engine by hand for a couple of turns so that any particles that have gotten down onto the rings will be lifted up and left behind when the pistons go back down. Then wipe the bores with a clean, oil-wet rag. When the inside of an engine is exposed you can't be TOO clean.

With the head off there's no better time to replace or at least remove and try to clean out the oil separator box.
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Bob: son's 81-GL, dtr's '94-940, my 83-DL, 89-745(V8) and 98-S90. Also 77-MGB and some old motorcycles.

Either way should work fine. Be sure you suck all the old oil out of the head bolt holes. Try to also replace the valve stem cushions. They're probably all worn out.

I put the pistons in a position half way down the bore and stuff the top half with rags. I use a die grinder with a wire brush and clean the top of the block being careful not to come in contact with any of the rags.

Carefully remove the rags and vacuum the bores. Wipe the surface with solvent.

Randy

In the cylinders that are down, stuff paper towels/shop rags to collect up your scrapings.
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Post Back. That's whats makes this forum work.

Hi,


That’s just what I do! It works really well. Be sure not to remove excessive casting material. I also wear a mask, because of the manganese and lead component of the fuel deposits (lead was present in appreciable amounts in motor fuel until 1993).


Goatman

Are you certain about lead being present in motor fuel until 1993? Lead is immediately fatal to O2 sensors and catalytic converters, and we've had three mid-eighties Volvos running the original catalytic converter with over 300,000 miles on them.
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john

A razor blade scraper works great for removing any deposits from the block surface. I wouldn't use the wire brush because you might lose some wires, and if you don't get all of them out from along side the pistons it isn't good. Don't use anything abrasive either. You can never get all of the abrasive back from alongside the pistons. Yes, just use a vacuum cleaner to get the debris out of the cylinders.
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john