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Prepping S3 Engine Mating Surface

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Old 03-17-2016 | 06:04 PM
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zekgb
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Default Prepping S3 Engine Mating Surface

So I am now ready to reassemble my engine and have been prepping the block mating surfaces using CRC gasket remover and plastic razor blades. After several hours I've been unable to remove all of the residue from the mating surface. The rust colored areas in particular still feel slightly rough to the touch, is this normal? If not normal then what else can I do to safely remove the residue in these spots?
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Old 03-17-2016 | 06:36 PM
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That staining won't come out unless you cut the surface, as long as it is smooth, flat and clean you wont have any issues w/ the new head gaskets sealing.

Edit: I would pick up one of Greg Browns Oil Fill baffles, that stock one is "Cr@#"
Like this:
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Old 03-17-2016 | 06:42 PM
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Greg's baffle is in there with the stock baffle installed on top, definitely reduced oil in my intake in the 1k miles I drove the car prior to burning a valve.
Old 03-17-2016 | 07:01 PM
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Oh OK good!
I don't think you need both of them as it would make more layers to seal up, being there's only the two # 10mm bolts pulling that sandwich together
Old 03-17-2016 | 07:36 PM
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Pretty sure Greg's instructions said to use both and it's all sandwiched together with dreibond which I guess is magic.
Old 03-17-2016 | 07:41 PM
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Using a Roloc disc usually does a good job on mating surfaces.
Old 03-17-2016 | 10:38 PM
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How about a flat sharpening stone? Should work well knocking down the high areas but ideally the block should be decked.
Old 03-18-2016 | 11:26 AM
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Roloc disc is a bit sketchy for a sealing surface as critical as a head gasket. Personally I wouldn't chance it. YMMV. With the studs installed it makes it a pain to do, but a super fine piece of sandpaper/crocus cloth on a piece of glass or flat steel so it prevents creating any low spots works. I didn't like the staining on mine because it made it hard to tell if there were any problem areas. So I cleaned it with PASA Jell 102. Stuff works wonders.

Now I'm trying to figure out how to clean out the coolant area around the cylinders.
Old 03-18-2016 | 11:29 AM
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Stay away from the sandpaper and glass combo if you can. A flat sharpening stone works anlot better, just keep it lubricated.
Old 03-18-2016 | 05:13 PM
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Those sealing surfaces need to be really clean, in my opinion.

I take apart the blocks and have those surfaces cut.
Old 03-18-2016 | 05:20 PM
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I wish I knew about Pasa-Jell 102 when I did a rebuilt 944 motor a while back. My block still had the stains, but the mating service for the head gasket was smooth after spending HOURS and HOURS of scraping as well as using gasket remover.

It couldn't hurt to try Chris' chemical recommendation first before opting to send the block out for a cleanup, which would up your costs as they would most likely recommend removing the pistons, rods and crank.
Old 03-18-2016 | 05:50 PM
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Do you have a supplier for smaller qtys of Pasa-Jell? Googling isn't turning up much, best I found was a whole quart for $230.
Old 03-18-2016 | 06:09 PM
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Flat honing stone is all that is needed. Knock down the high spots left by prying and banging things around. the critical area is the fire ring. Imre is right to keep it lubricated(water is fine) . Place rags in the cylinders and apply a ring of grease at the top of the cylinder. That should catch any aluminum filings (there won't be much at all). Pull each rag and clean out the bore before rotating the crank.
Old 03-19-2016 | 08:41 PM
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Originally Posted by zekgb
Pretty sure Greg's instructions said to use both and it's all sandwiched together with dreibond which I guess is magic.
I don't use a gasket between any of these layers.

The stock baffle works very well, sitting on top of my oil separator.

Make sure the filler neck is flat....usually not, so usually will need to be made flat.

Use thin layer of Dreibond between each layer. Tighten bolts to 72 inch pounds. Wipe off excess.
Old 03-21-2016 | 12:01 AM
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I went with the razor blade 90° scraping method. After the better part of the afternoon I managed to get all of the rust colored deposits and I'm only left with the black staining on the deck. I've only used a plastic scraper on the bore sealing surfaces but they all feel very smooth.



Last edited by zekgb; 03-21-2016 at 12:48 AM.


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