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Thread: Prep Engine Block Deck and Cylinder Head Mating Surfaces for New Gasket

  1. #1
    Commander Member
    Join Date
    May 2016
    Los Angeles, CA

    Prep Engine Block Deck and Cylinder Head Mating Surfaces for New Gasket

    Any tips, dos, don'ts, for mating surface prep for new gaskets? I am doing prep work before re-installing cylinder head onto engine block... Mind you, this is a cast iron block.

    From what I've read, there seems to be heated debate about what is the best way to clean and prep each surface.

    Here's what I've read/viewed:
    1. Some say use 3M Scotch-Brite Roloc Bristle Disks attached to a drill, others say never use because you can round off edges of the deck.
    2. Some say use 3M Scotch-Brite Scouring Pad (red or green), others say never use because you can scratch the surface too much.
    3. Some say use a wire wheel on a drill, others say this is too aggressive.
    4. Some say use a blade scraper, others say not to because you may gouge the surface
    5. Some say to use fine grit sand paper and a sanding block, others say it makes for too much dust and particles that can get "into the engine"
    6. Some say to spray shaving cream into the water jackets and various holes in the block to prevent particles from falling into the holes

    I have noticed so far in examining the engine block deck.. there is hard crusty buildup in the holes of the engine block deck... some is dark black, some is light brown in color... I imagine pieces of this crusty stuff will easily fall into the holes when scraping, scrubbing... here are some pics:

    IMG_1292.jpg IMG_1293.jpg

  2. #2
    Commander Member
    Join Date
    Sep 2009
    Watts, OK, USA.
    I use a putty knife aka a painters knife,sharpened on the end with the corners rounded off.If I need to prevent the trash from going into the engine I hold the end of a shop vac. next to the scraper.

    to sharpen hold putty knife at about 20 to30 degrees on the side of a grinding wheel.Dont hurt to finish with a few strokes on a oil stone.

  3. #3
    President Member BRUCESTUDE's Avatar
    Join Date
    Jan 2005
    Yakima, Wa, .
    I use a razor blade type gasket scraper (with a shop vac as Chipmaker sez) then I follow with a blue Scotch Brite sponge/pad (doesn't scratch) with a little solvent on it followed by a rag and bare fingers to check for any spots I missed.

  4. #4
    Speedster Member
    Join Date
    Aug 2016
    North Port Fl
    I like wet and dry sand paper with mineral spirits or stoddard solvent.

  5. #5
    Golden Hawk Member StudeRich's Avatar
    Join Date
    Dec 2005
    Ferndale, WA, USA.
    Do not worry too much about getting whatever abrasive you use into the Water Jacket Holes, it is easy to knock out a Core Plug and flush it out.

    What you need to be concerned about is getting debris into those Push Rod Holes and into the Crankcase!

    The other place to keep very clean is in the cylinders, as debris will lodge between the Piston and Cylinder Wall.
    You could try sealing that gap with wheel bearing grease. Carefully removing it when finished should take a lot of debris with it.
    Second Generation Stude Driver,
    Proud '54 Starliner Owner

  6. #6
    President Member
    Join Date
    Apr 2005
    Sharpened scraper.
    New razor blade for stubborn areas.
    Clean rag with lacquer thinner to finish.

    Just don't go crazy with what-ever you use. Use care because most everything mentioned can...damage the deck surface. I would NOT use any sand paper of any kind, unless it's mounted to a hard, flat block of some kind. Like maybe a body tool, and even then, use great care to not use it like a rag (short strokes)...use it like you were carefully sanding (long strokes) fresh Bondo and preparing for paint..! Then "lotsa" cleaning.


  7. #7
    President Member
    Join Date
    Mar 2008
    , , .

    A lot of "don't do this" without any "DO do this."

  8. #8
    President Member swvalcon's Avatar
    Join Date
    Apr 2012
    princeton mn
    I just put a sheet of 40 grit on my air file and hit it once over. Makes it look like new.

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