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Engine Specific Info and Questions => IDI Engine => Topic started by: 92EcoDiesel Jetta on July 29, 2011, 06:42:52 am
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What's the best way to clean the block surface in preparation for a head gasket install? Bear in mind that the block is in the car so can't put it in a hot tank or parts washer afterwards.
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i use a die grinder fitted with scotch bright pad...
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i use a die grinder fitted with scotch bright pad...
Scotch brite is too abrasive IMO, use a piece of brass, or mild steel
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Really? Scotch Brite is too abrasive?
CRSMPS, you mean the plasticky, rough pad, not the steel wool, right? Like this stuff:
(http://www.4mailers.com/Images/ProductImages/3734_xl.jpg)
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On a die grinder he means these
(http://site.skygeek.com/yswimages/3m-roloc-scotchbrite-disc-tr.jpg)
Not too abrasive if you can get the super fine. Maybe ok with the very fine. But nothing coarser. Even the very fine is capable of radiusing the corners of water passages and making leaks if you aren't careful.
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Really? Scotch Brite is too abrasive?
CRSMPS, you mean the plasticky, rough pad, not the steel wool, right? Like this stuff:
(http://www.4mailers.com/Images/ProductImages/3734_xl.jpg)
I think that plastic is a misnomer, I think that's harder than steel wool. Having said that, the fine scratches will probably help the gasket bond.
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been using red round ones for 25+ years... even on head surface... if you worry.. do it on block.. then use same pad on head.. it is much more worn in that order.. and simple.. do not sit in 1 area too long.. your just cleaning it up... :D not decking the block/head.. and honestly.. you would really have to work at it on the block to screw it up...
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I'm with ya CRSMPS but, you'd be surprised what those little discs can grind.. That being said I've used them cautiously if I'm going to be using a fiber gasket.. With a MLS, no way!
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I don't have air tools here or those Scotchbrite pads. I do have a scrap piece of1/2 thick Lexan 4"x8" so I taped a piece of 400 grit wet dry paper to it for a sanding block.
(http://i1183.photobucket.com/albums/x480/Ecodiesel92/Photo_073111_001.jpg)
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(http://i1183.photobucket.com/albums/x480/Ecodiesel92/Photo_073111_002.jpg)
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I hope 400 grit is not too coarse. I used WD40 as a lube/cleaner.
before
(http://i1183.photobucket.com/albums/x480/Ecodiesel92/Photo_073111_003.jpg)
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Cleaned up really well.
After
(http://i1183.photobucket.com/albums/x480/Ecodiesel92/Photo_073111_005.jpg)
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Sorry, it seems I posted the same pics twice, twice! Couldn't see it I was on my phone on the WAP site. Fixed!
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scotch brite lot less harsh then 400 grit.. :P
how did you clean the head??
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I used the same 400 grit sanding block on the head after using it on the block.
I've read that cylinder heads on performance engine are finished to RA 50. I did a search for RA 50 and came up with a table of stainless steel surface finish in this thread:
http://www.finishing.com/98/42.shtml
Per the table, RA 50 is around 130 US grit, so the 400 grit I used is not too coarse, but too fine.
I assume you do not want a super smooth surface on the head and block such that the head gasket can slide around against but rather a coarser surface like 130 grit to "bite" into the head gasket. I am just theorizing so forgive me and set me straight if I am wrong.
scotch brite lot less harsh then 400 grit.. :P
how did you clean the head??
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scotch brite lot less harsh then 400 grit.. :P
how did you clean the head??
I sell 3m and the maroon scotch brite is in between a P150 and P180 or exactly equal to ansi 150. The very fine = greenish blue is in between P360 and P400 grit. If anyone is interested I could post a chart showing different grades, they even have micron grades in Trizact
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I never knew what the colors coresponded to, grit wise, so I'd be interested in seeing a chart.
Otherwise, I always thought:
brown = coarse
red = medium
blue = fine
gray = ultra fine
I was never sure where the green pads fell.
-Todd
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The green hand pads are identical to the maroon hand pads but they are safe to eat. Selling to dairy companies you have to sell the green, but grit wise they are medium just like the maroon.
In the roloc discs the blue to me is green. It looks green to me anyway and that is why I always say greenish blue. I will copy the chart and post it soon.
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The green hand pads are identical to the maroon hand pads but they are safe to eat. Selling to dairy companies you have to sell the green, but grit wise they are medium just like the maroon.
In the roloc discs the blue to me is green. It looks green to me anyway and that is why I always say greenish blue. I will copy the chart and post it soon.
A bit like Shredded Wheat then ;D
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(http://a3.l3-images.myspacecdn.com/images02/131/be81cacaaff5428f8a07c3f43d16ada2/l.jpg)
I can read it on my screen but not great. If you have a 19" LCD or bigger like me it should work.