Head gasket Repair - How to clean the block deck with the pistons installed.

[BogusSVO]

Head Gasket Repair
How to Clean the block surface
Pistons installed.


This is for a composite gasket, NOT a MLS.

The subject block is a 4G63, 7 bolt

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First roll the crank over till all 4 pistons are at mid stroke

Now find some sort of grease, I am using wheel bearing grease

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Get a finger full

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Now smear it into a seal around the wall of the cylinder and piston

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Now as the block deck is cleaned, the grit will not work down on the rings.

Now the head alignment dowels need to be removed, find something, back side of a drill bit, large bolt, or a ¼ drive socket, Is should be close to the ID of the dowel.

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Now take vice grips and clamp onto the dowel.

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Start with wiggle movement, going to a twist when you feel movement,

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Walk the dowel out of the block.

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I prefer a long hard back body board with 80 grit sandpaper.

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Now go over the deck surface with light to moderate force to remove the gasket residue.

Use different angles across the block.

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Once all the residue is removed, rotate the engine over, so one pair of pistons is at TDC.

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Now with rags, or blue paper towels, wipe the grease away, Wipe the Pistons at TDC, and the walls of the cylinders that are at BDC

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Now rotate the crank 180*, and repeat.
Do this till you can see the top ring on the piston at TDC.

Once the grease is cleaned up, Wipe the cylinders with a blue paper towel with clean engine oil on it.

Use a solvent, such as brake cleaner, and wipe the block deck.
Install the head alignment dowels back in.

You are now ready to install your head gasket, and finish your build.

 

[4gfun]

I see, thanks.

Those are a lot more abrasive than the one that I use. The bristles are real fine on it and it is a wheel, not a cup.

 

[4gfun]

Those are a lot more abrasive than the one that I use. The bristles are real fine on it and it is a wheel, not a cup.

Could you tell me exactly what I need to pick up and where to pick it up from? I think that I have a pretty good idea, but don't want to assume anything.

 

[4gfun]

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these are the results of this garage decking method i achieved.

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i decked this block using this method and instead of the long hand sander, i used a 13x13 porcelin tile that is FLAT. i spray adhesive onto the tile and applyed 80 grit sandpaper it take it down. it took three sheets of 80 grit paper and 1 hour of labour. i stacked the tiles on top of eachother and ther pile weighed probably 20-30 pounds. after i got down to flat, i switched to 150 grit to finish.

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Man that is gorgeous. Nice implementation of the technique!

 

[ncdsmer]

Good how too for composite gasket removal. Will have to remember this method the next time vs removing the pistons

 

[4gfun]

Where is the oil port that needs to be blocked?

 

[darknezz7]

80 seems so coarse, as long as you are FLAT I guess it would be ok. I've used rolocs on iron blocks in the past, now I use a soft wire brush and acetone. The last few aluminum blocks I did I used 220 grit then 600, mls head gasket was stock. They seem to be doing well.

I like the grease idea, I usually just put a paper towel in the cylinder to catch most of it, then use compressed air nose and carb sray to clean around the piston real good moving it up and down cleaning the wall. Crude in passages should also be able to be sprayed out with compressed air and or flushed.

 

[BogusSVO]

Where is the oil port that needs to be blocked?

On a DSM block the oil port is on the exhaust side of the block on the pass side. About .250 Dia.

 

[4gfun]

On a DSM block the oil port is on the exhaust side of the block on the pass side. About .250 Dia.

Is this it? Dial calipers found these to be pretty much .250 diameter. Also, what would you protect it with? I am considering paper towels or grease but I think both have their drawbacks. Scared a paper towel would get stuck in it! Worried about grease just falling down into the hole along with shavings.

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[BogusSVO]

Yes that is it.

The tear drop shaped hole in the HG will go around that oil port and the head stud.

It is the same shape as the oil port mod done in the head.

**EDIT**

Those look to be NA pistons, 63D
The turbo pistons are 63DT

 

[4gfun]

Yes that is it.

The tear drop shaped hole in the HG will go around that oil port and the head stud.

It is the same shape as the oil port mod done in the head.

Yep I noticed that. I think we posted at the same time. What about covering that hole while doing this? Scared that paper towels or grease have their own drawbacks.

Thanks

Yes that is it.

The tear drop shaped hole in the HG will go around that oil port and the head stud.

It is the same shape as the oil port mod done in the head.

**EDIT**

Those look to be NA pistons, 63D
The turbo pistons are 63DT

Wow, car is down for a year and now this....lool!

Guess I'll shoot you an email about this.

EDIT** I just checked and they are indeed 63DT pistons....thanks for catching that...optical illusion!

All, I got the sanding board he is referring to for only 7 bucks at Harbor Freight. I got the sanding strips at northern tool.

 

[miliman13]

I too have always used a razor blade in the past. And I was careful enough to not need grease, but it did take a long time.

I always thought Rolocs were OK to use on the deck of an iron block to remove composite gasket residue. Is this not true? I can't imagine soft plastic can cause damage to iron, but maybe I'm wrong.

Hey bud found this, though of you.

Art's Automotive Berkeley, CA -- misc pictures & info

 

[4gfun]

Highly suggest having a smaller block sander ready as well. There is a bracket on the driver's side that gets in the way unless you remove it first.

EDIT: The bracket is easy to remove. I just removed it.

 

[88BB8B]

I know this is a super old thread, but i noticed nobody seemed to mention anything about the oil drain holes from the head. They are the largest holes on the deck and they lead straight to the oil pan. I magine relying on your oil filter to collect any metal dust/sanding grit falling down there would be inadvisable. I would suggest blocking those off as well. When I do this I'll likely turn the block upsude down. Thats the best way I can think of to make sure it stays clean.

 

[pauleyman]

I know this is a super old thread, but i noticed nobody seemed to mention anything about the oil drain holes from the head. They are the largest holes on the deck and they lead straight to the oil pan. I magine relying on your oil filter to collect any metal dust/sanding grit falling down there would be inadvisable. I would suggest blocking those off as well. When I do this I'll likely turn the block upsude down. Thats the best way I can think of to make sure it stays clean.

If the block is out of the car I wouldn't do this with anything in it so no need to be upside down.

I also like carbide scrapers better than razor blades. I did a block a few weeks ago and the scrapers got stuff the razors didn't. Have to have a light touch as these scrapers are hard and can gouge the surface if abused.

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I was a little surprised by these.

 

[Yokai]

I know this is a super old thread, but i noticed nobody seemed to mention anything about the oil drain holes from the head. They are the largest holes on the deck and they lead straight to the oil pan. I magine relying on your oil filter to collect any metal dust/sanding grit falling down there would be inadvisable. I would suggest blocking those off as well. When I do this I'll likely turn the block upsude down. Thats the best way I can think of to make sure it stays clean.

You should use a thick glass sheet with sandpaper sheets adhesived to it. It's much bigger and flatter than a sanding block. I think I used something like 400-600-800 on mine, there's not really that much grit as long as you're just cleaning. Plugging the holes is a good idea, I felt like my normal paper towel wads would have fell in so I swabbed vasoline around the holes to catch grit instead. The oil filter will easily grab anything else and just do an oil change after a very short period. you can see progress pics in my thread (where I was also questioned about the drain holes)

Razors and roloc discs are not suitable to convert to an MLS gasket which requires a much smoother surface and is less forgiving of imperfections

If you have the engine out, you should just be taking it to a machine shop. The only reason to fuss with this BS is if you can't or won't pull the engine

 

[jakk220]

I personally would never use this method to clean a block, but it should also be mentioned that you are going to need to clean the grit out of the head stud holes/threads as well. All you should need to clean it is a razor blade, some patience, and some brake cleaner.

 

[Red Rider]

I'm about to do this myself. The machinist I used for the head recommended a gentle razor blade followed by a carbide scraper. That's the plan. No abrasives.