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Getting ready to reassemble my 5.3 and need to know how to clean the composite gasket material from the heads & block. DO I block out the heads with WD-40 & wet or dry paper on a flat bar (2x3 steel).
Block is iron, so thinking that would be those red scratchy pads on a die grinder (so as not to remove any steel from the block).
Aluminum is soft, so you'll have to be careful not to gouge the surface. Sand paper is OK at the very end just to give the surface some texture for the gaskets and to make sure everything is flat. If you get too aggressive with a tool you can damage the surface and the head gaskets won't seal well. Take it slow and easy with a scraper that won't dig into the aluminum. You'll get a lot of advice so choose wisely.
Oven cleaner and a rubber scraper. If you do use a razor blade, keep it perpendicular at all times.
If you go with sandpaper, don't go any more fine than 400 grit. You want about a 50ra surface finish...too smooth can actually be a bad thing.
Ideal method is to take them to a machine shop and have the block decked and the heads surfaced just minimally, but that's spendy and often unnecessary.
Like every other job, use the correct tools for the job. For alum heads, use a plastic scraper specifically designed for this job. If you're very careful you can use a carbide blade, but you have to be very careful with that.
Sandpaper can be used but again you have to be very careful. Use a stiff sanding block and make full strokes. Don't sand any more than you really have to, so you don't end up with high and low spots.
Old fashioned head gaskets needed a little bit of texture to seal well and prevent shifting. 80-100 used to be O New MLS gaskets - Cometic and stock GM - do not. MLS gaskets need a surface that's a little bit smoother that what used to be acceptable. Cometic specifies 50 or less. But Fel-Pro accepts 50-60. Check with your gasket maker and see what they recommend.
Go to Walmart and pick up a jug of Super Clean, it's in a purple 1 gallon jug. Get a spray bottle and some rubber gloves, you'll need them.
I'm not exaggerating when I say this, use it full strength, spray it on there, let it sit for a few min, then spray it again and the stuff literally starts falling right off of it. There was literally only a couple places inside the ports that I scrubbed and these heads had over 250k miles on them. I just rinsed them with water and was surprised. I honestly just kept spraying the heads with it and it melted it all away until they were clean. This was before I cleaned off where the gaskets went for the valve covers and manifolds. But trust me, you will be shocked once you try it, it literally started laughing when it dissolved off and I was standing there ready to scrub.
Wear gloves or you'll have alligator skin, this stuff is no joke.
Deeohgie69,
wow. thanks for sharing. If anything works THAT good, you know its not safe for skin. I hope you don't have any unknown lasting effects. That stuff did wonders.
gsjimmy
EAGLE 1 mag wheel formula (NON polished wheels) works wonders too. There are several formulas out know. You have to read the bottle to find the right one. You want to look for the mild acid formula. It will say it on the bottle in the directions / warning section. It will work wonders. Between this and gsjimmy recomendation, you shouldn't have any problems.
If the heads were grubby, I'd use what gsjimmy used, then the EAGLE1 mag formula.
Last edited by Jimbo1367; Jul 6, 2016 at 08:45 AM.
No way I'd use oven cleaner (sodium hydroxide or lye) on aluminum. It reacts with aluminum (how Draino works) and it even says on the can not to use it on aluminum.
No way I'd use oven cleaner (sodium hydroxide or lye) on aluminum. It reacts with aluminum (how Draino works) and it even says on the can not to use it on aluminum.
I use some stuff that is basically straight sodium hydroxide..in this thread, post #48, you can see the after is quite convincing. I am hesitant to try it on cylinder sealing surfaces but for the topsides and ports I think it would do well.
Well, looks like the purple stuff from wally world. The motor was sold as a 60,000 mile motor. From the look of it, should be correct. Will use a flat bar to sand at the end to check for flatness.
From: Halfway back on the Highway to Hell...again!
If you have an air supply and a 90* die grinder, you can use the roloc discs. But beware, not all companies use the same colors for grit reference.
I use strictly 3M.
Brown - Med - for cast iron
Grey - fine - Iron or on non-sealing aluminum parts
Blue - very fine - Aluminum - But don't wanna push hard. With the right touch, you can damn near polish aluminum
Been using them for many years and never had an issue. Just picked up another box of 50 today.
Another roloc style is the little ones with bristles. Manufacturer Color plays a part here too. I have a few. I think Green is Med and white is very fine. But don't quote me. I don't use them much.
As for the cleaning, I have a parts washer that does ok, but I too use a tote filled with Purple Power.
Getting ready to reassemble my 5.3 and need to know how to clean the composite gasket material from the heads & block. DO I block out the heads with WD-40 & wet or dry paper on a flat bar (2x3 steel).
Block is iron, so thinking that would be those red scratchy pads on a die grinder (so as not to remove any steel from the block).
If you have an air supply and a 90* die grinder, you can use the roloc discs. But beware, not all companies use the same colors for grit reference.
I use strictly 3M.
Brown - Med - for cast iron
Grey - fine - Iron or on non-sealing aluminum parts
Blue - very fine - Aluminum - But don't wanna push hard. With the right touch, you can damn near polish aluminum
Been using them for many years and never had an issue. Just picked up another box of 50 today.
Another roloc style is the little ones with bristles. Manufacturer Color plays a part here too. I have a few. I think Green is Med and white is very fine. But don't quote me. I don't use them much.
As for the cleaning, I have a parts washer that does ok, but I too use a tote filled with Purple Power.
I like using the bristle brushes on anything aluminum. But if super clean works that well there will be no need for it unless you are working on something in car.
Lacquer Thinner for sure. Just wear gloves. It breaks pretty much everything up. I cleaned all the carbon off my motor with it. Just let it soak and agitate a little. Works great on gasket material too.
Heads... I throw them in the dishwasher when the wife isn't looking
For the block, I use "Aero-Croil" which makes PB Blaster look like a joke, and a razor blade. Hold the razor DOWN as far as you can, and use short little motions. Works like a charm. I've never used cleaners or pads or any of that stuff.
Heads... I throw them in the dishwasher when the wife isn't looking
For the block, I use "Aero-Croil" which makes PB Blaster look like a joke, and a razor blade. Hold the razor DOWN as far as you can, and use short little motions. Works like a charm. I've never used cleaners or pads or any of that stuff.
You know, I am always inspired when I see this posted, intend on trying it "next time" and then quickly forget. Going to have to put a sticky on a dirty set of heads to remember next time. Dish detergent is no joke...add the heat and agitation and you've got a pretty potent parts washer.
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How do I clean aluminum heads? 
