Be careful using abrasive pads to clean head gasket residue
I always hate how it takes 2+ hours to clean head gasket residue off a block, so I took the advice of an auto parts store manager and tried those little abrasive disks that you can spin with a drill.
Things were going fine until I scratched the top of the cast iron sleeve.
The small scratch ran out from the cylinder toward the cooling jacket so I knew the solid metal ring on the head gasket wouldn't seal it. By the time I had polished it out with 400 grit sandpaper, I had taken .002 inch off that spot (as measured with a straight edge). The tip of the screwdriver points to the spot.
I was too nervous about the new head gasket sealing this "divot" so I decided to play it safe and get it flat. I had to strip the block and take it in to the machine shop to get the deck refinished.
So, just take your time and spend the 2 hours scraping the head gasket residue off with a razor blade and maybe a little steel wool. Otherwise, you might spend an extra 4-6 hours and an extra $50 to get the block machined. Thankfully I already had this block out on an engine stand when I messed it up.
Another issue that I have read about (after the fact) is the abrasive grit that these pads will leave behind in your cylinders.
I have read several places and been told by knowledgeable experienced people to never use abrasive pads to clean a head or any other mating surface for exactly the reason your post illustratates. solvents and razors (or other suitable hard flat sharp edge), no matter how long it takes.
don't forget to take the rags out, I've seen people forget and leave them in intakes, the rag wrapped around the camshaft on a v-8 and broke it. or someone got one sucked down the intake and into the cly. I only use the abrasive disks on iron blocks, alum parts we should use a chemical that loosens the gasket and using an old ice scraper(plastic is good) it comes right off. or a brass scraper not hard metal. they do make soft abrasive disks but that takes forever to remove gaskets.
^^^yea a razor blade can carve right through aluminum... not that I'd know
on my cressida, I spent about 4 hours on the block and more on the head but it's a straight 6.
1991 Toyota Pickup 22R-E 2.4 I4/5 speed
1990 Toyota Cressida 7M-GE 3.0 I6/5-speed manual
mechanic, carpenter, stagehand, rigger, and know-it-all smartass
"You don't get to judge me for how I fix what you break"
I always used abrasive, both when working in a shop and on my own cars - never a problem.
However, I would not recommend doing it with a drill, as in that application it's to awkward to hold and you don't have the control you need. Just get an air angle grinder for ~$20 like this:http://www.harborfreight.com/cpi/cta...emnumber=93157 I've used it on many engines - cars, bikes, outboards - you name it.
Razor-blades are scary with the aluminum parts. I've never used the abrasive disks personally but I have used some course steel-wool. Never had a sealing problem afterward. I should have used some solvent though, that is something I will do next time for those aluminum surfaces.
On the never-ending quest for better gas mileage...