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DIY Guru
96 Ranger-stock
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637 Posts
Discussion Starter #1
How to Clean a Head Gasket Surface

There are many ways to clean a head gasket surface.
This is just one way, and it is the method I prefer.

I do not like the use of “rol-locs” for cleaning a head gasket surface, for block or head.
Cast iron or aluminum.

This is for COMPOSITE Head gaskets, Not MLS

MLS Head gasket surfaces need more prep.

A rol-loc can an will “wave” a gasket surface when used improperly. In most cases it is.

So do not use this!!


What I prefer to use is a hard back body board with 80-100 grit sand paper.




The reason to do it this way is….
1) more coverage area
2) will not “wave” the gasket surface
3) will show low spots in the gasket surface

Use moderate pressure when going over the gasket surface.


and go at different angles, using long steady strokes


and




You want to go over it enough to just “shine” the surface and remove all the old traces of the head gasket but not remove the metal of the block or head.


You should end up with something like this.


Now the surface is prepped so the head can be checked for warp and other imperfections.


Notice the dark marks above the exhaust valves and around the water ports, this shows the low areas and fire rings.

This head needs to be surfaced so to hold a head gasket properly.
 

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Yikes that thing needs to be milled.

80 grit won't leave a seal-able surface. It needs to be like a mirror.

Don't "clean" a head like this and then expect to put it back on.

My preferred method is still solvent and a razor blade. It's slow and tedious but will leave a seal-able surface.
 

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DIY Guru
96 Ranger-stock
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637 Posts
Discussion Starter #3
yes it did need milled.

With a composite HG and the head flat this method will seal and be just fine.
With a MLS HG, thats when it is dicey,

The surface finish has to be correct for the head gasket being used.
 

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My preferred method is still solvent and a razor blade. It's slow and tedious but will leave a seal-able surface.
Yeah, I normally use a plastic scraper and solvent for the majority of the job. An old credit card also works if you have nothing else available. For stubborn spots, I'll carefully use Scotchbrite and solvent.
 

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Meat Popsicle
91 CRX Si
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2,936 Posts
My god, 80-100 grit??

I realize that you do machine work but this is the absolute last thing I would do aside from the angle grinder which you mentioned in your other thread.

Safer scraper, roloc discs, non-scratch dish pads...all things I would try before I used sandpaper, especially of that grit
 

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DIY Guru
96 Ranger-stock
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637 Posts
Discussion Starter #7
If it was on a power tool It would do horrid dammage

But by hand on a long board, there is the slightest os scratches.

the grit clogs quick with gasket and carbon
 

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crx
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2,683 Posts
For the block I use a wire wheel on a drill but I don't put a lot of pressure against the surfaces when doing it. for the head and cylinder portion of the block I use a soft plastic wire brush. than when I'm done with that I clean everything up with brake cleaner and a fresh rag. this method always worked great for me.

I never really cared for the permatex copper seal, if the car manufacturers don't use it why should I ?


 

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Classic Man
Civic
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I would say use something like 200 grit then 300 grit or so. This will work if done very carefully, evenly, and consistently.

The problem is most people dont know how to block something evenly, and the edges will be low spots, the center of the cylinder head a high spot, and the chances of people screwing it up are greater than the chances of it working out. IMHO.
 

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Love the Civic
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I think the op is old school and he has a touch few probably have, just approach this as with any technique with caution. There is a reason we pay good money to have a knowledgeable machinist do the head and block work.

I dont think he means any harm with the thread, just not a rookie job, no matter what the material. In fact it is nice to see some insight to what a shop is doing for those less in the know. I am not doing anything but scrapping my gasket off, if it looks warped upon straight edge, I step away from the head.
 

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all i see is 1 spec of sand in a guide ruining your day... less than $200 pretty much anywhere in america, milled, and a valve job

maybe just maybe if it was completely disassembled and you finished with 2000 grit, but this is just a waste of a good head in my opnion
 

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DIY Guru
96 Ranger-stock
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Discussion Starter #14
I think the op is old school and he has a touch few probably have, just approach this as with any technique with caution. There is a reason we pay good money to have a knowledgeable machinist do the head and block work.

I dont think he means any harm with the thread, just not a rookie job, no matter what the material. In fact it is nice to see some insight to what a shop is doing for those less in the know. I am not doing anything but scrapping my gasket off, if it looks warped upon straight edge, I step away from the head.
yes I am a bit old school, I grew up around domestics from the time I could walk. Rebuilt my first engine back in '87
Went to votech from '91-'93
Started in machine work in '92 that majored in ford small blocks
Worked in a few other shops, most small, but a couple large production shops
In one I learned about "full pull" tractor stroker cranks.
Started my own shop in '02

Like I stated in the beginning, this is the method I use, there are others that work just as well, the main thing is you are comfortable with it and you trust it.

The razor blade method is a good one, but is slow and time consuming. but nothing wrong with it as long as you do not gouge the surface.

This method that I laid out is commonly used in shops in the country.

I personally do not like rol-loc abrasive disks, shown in the first photo. So I advise to keep away from them.

all i see is 1 spec of sand in a guide ruining your day... less than $200 pretty much anywhere in america, milled, and a valve job

maybe just maybe if it was completely disassembled and you finished with 2000 grit, but this is just a waste of a good head in my opnion
With the vales in, I doubt a a bit of grit would make it into a guide, Considering most guide clearance is less than .002, or less than .001 at any 2 points 180* from one another.

You be more likely to get carbon flake from cleaning the exhaust gasket surface and/or runner in there. Or some sort of carbonized oil from the egr/pvc system on the intake side.
 

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0000 Steel Wool is for polishing, Has a hard time wearing aluminum away but cuts through rust and gunk Fantastically, especially with a touch of WD-40!

When using wire brushes or wheels, I strongly recommend Brass over Steel when working with Aluminum, as the Steel can erode the base metal faster than a similarly performing Brass brush!

Also use an oil or Lubricant, (Again WD for me) to reduce the effects of tracking from abrasives.
 

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97 honda coupe
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This is an old school trick, we used to do it on cast iron heads where i worked with a machinist stone. Although it may work on graphite headgaskets id be more than worried about using an MLS gasket with a surface like that. With an RA of 80-100+ your turning that head into sandpaper that is abrasive to the gasket with expansion and contraction during heat cycles. On a composite gasket its probably not noticeable as they basically vulcanize to the mating surfaces anyways.

i would do this is if i wanted to find if the surface was warped, or had high spots. Probably would use 300 or 400 grit sandpaper and a piece of marble/granite finished flooring tile. But around here 30$ gets a stone surfaced head so its hard to see doing this by hand and chancing it.
 
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