Cleaning mating surface of block

[E30 Wagen]

I'm getting ready to bolt on my freshly rebuilt 731 head onto the eta block I've had sitting for 7+ years. I made sure the keep the cylinder walls oiled but I didn't do as good a job on the mating surface, and there are a couple spots where there is some surface rust. I've googled some ways to address this, but I'm wondering if anybody has dealt with the same issue and what the safest way to clean it was. Thanks.

[TurboJake]

Getting it milled. Even surface rust causes pitting in the metal, so you'll need to address that for a proper seal. If you really don't want to go that route, wirebrush away.

[scarecrow]

Hit the deck surface with a plastic abrasive disk on a right angle grinder and slap the head on. As long as the rust isnt extreme you will be fine

[whodwho]

You can use a sharpening stone, I have a nice 2 grit one and works well to clean and keep it flat.

[AndrewBird]

If you can't feel it with your fingernail, an abrasive pad or wire wheel will be just fine. If you can feel it, there is likely pitting. How bad the pitting is will determine what needs to be done. Minor pitting isn't that big of an issue. Just clean it up and go.

[TobyB]

I like the whetstone idea. I use fine grit auto body paper on a sanding block, carefully.

And then clean the bejezzuz out of it.

t

[E30 Wagen]

If you can't feel it with your fingernail, an abrasive pad or wire wheel will be just fine. If you can feel it, there is likely pitting. How bad the pitting is will determine what needs to be done. Minor pitting isn't that big of an issue. Just clean it up and go.

If there is pitting, is there any product that can be used to fill it in and level it out, ie; some kind of high temp gasket sealer that would be safe?

[digger]

is the block still in the engine bay or this disassembled off the car

[E30 Wagen]

is the block still in the engine bay or this disassembled off the car

It is out of the car but the rotating assembly was never touched. I really don't want to take it all apart if I don't have to.

[raudonis]

I've used scotch brite for rust removal with great success on rocker cover, waterpump, thermostat housing and sump mating surfaces on my m20.

[Cabriolet]

I've used scotch brite for rust removal with great success on rocker cover, waterpump, thermostat housing and sump mating surfaces on my m20.

ASE just put out a memo, last year, on this. using scotch brite can leave material behind and cause catastrophic failure of the cylinder rings and other moving parts.

If you choose to use this, clean it VERY well after.

[pandaboo911]

ASE just put out a memo, last year, on this. using scotch brite can leave material behind and cause catastrophic failure of the cylinder rings and other moving parts.



If you choose to use this, clean it VERY well after.

+1 do not fucking use scotch brite. I used it and the abrasive dust got everywhere. I was lucky because I plugged all the oil passages beforehand , and managed to clean out the cylinders with water and compressed air.

If you do it anyway, get some high quality scotch brite and check beforehand to see if it leaves dust behind.

But please, get yourself a flat sanding stone or something equivalent, and prep well. I also did an oil change and ran an oil flush treatment after just to be sure none of that dust ruined all the pricey machine work I did.


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[NZM3]

ASE just put out a memo, last year, on this. using scotch brite can leave material behind and cause catastrophic failure of the cylinder rings and other moving parts.

If you choose to use this, clean it VERY well after.

Yes you are quite right what I do after cleaning is apply oil around the bore and turn the crankshaft to move the piston up in to the oil and then back down and wipe the grit and debris away and continue this process until only clean oil come back out.
Hope this makes sense give it a go and see what I mean.

If the engine is still in the car and you just want to refit the head use the sharpening stone method must be new or in still flat condition and using the smooth side only with some light oil etc.

If the engine is out for a rebuild get it machined flat.
Dave.

[Tisoc]

Lots of 'em.