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By 46yblock - 16 Years Ago
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I stumbled upon this guide in ebay, provided by member machinedave0 . It englightened me, so am passing it on:One of the biggest mistakes I see my customers make when they come into our automotive machine shop is there use of the rotary gasket removing disc. These are made buy several companies and they claim that they "only remove gasket material". Many well intentioned people use these discs on there die grinders to quickly remove gasket residue from cylinder heads and manifolds. Its quick, easy and brings the sealing surfaces down to bare clean metal, but it also leaves small pits and valleys in the sealing surfaces, especially around edges and corners. Customers have brought me there cylinder heads that have been cleaned with those "safe to use discs" for resurfacing and in some cases I have had to resurface up to .003" more than needed due to the aggressive nature of those discs. In response to some of the complaints of these discs, several years ago the manufacturers of these discs offered a new, less aggressive and safer version of the discs that were not much better than the old ones. Many automotive dealers and shops have created a zero tolerance policy on the use of these gasket discs buy there techs. The problem is even worse for engines that use MLS gaskets (multi layer steel) that require a very smooth surface finish to seal properly. The damage caused buy these discs is easily noticed when resurfacing the head. The first pass on the resurfacing machine will reveal the flat areas and will show all the valleys created buy those gasket discs. The best way to remove gasket material safely is to use a carbide scraper. They are very sharp, machined perfectly flat and safe on aluminum. They are available from most shop supply companies for about 30 bucks. They will remove the gasket residue without removing metal from the sealing surfaces. You will still see the gasket stain but thats all that it is remaining, just a stain left from the old gasket. As an owner of an automotive machine shop my advise is do not use these discs and if you have bring the parts to a machine shop to have the heads resurfaced properly before installing them.
Guide ID: 10000000005686042Guide created: 02/16/08 (updated 01/10/09)
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By charliemccraney - 16 Years Ago
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I just carefully remove the gasket with a razor blade.
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By mctim64 - 16 Years Ago
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I am very glad you brought this up. I have been telling My customers for years to throw these things in the craper. I will bring a guy back to the surfacer and show them what is left after a .003" cut and they are amazed to see the rolled edges into the combustion chambers. It's no fun to argue with a guy that has blown a new head gasket that it's his own fault for cleaning the gasket off that way. Also try to explain that the only proper way to fix a block is to pull and disassemble the engine completely so it can be resurfaced after the deck was ruined with one of these things. The guy who sold this process should be strung up! OK, maybe I'm being a little harsh, but it's something I feel strongly about. 
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By mctim64 - 16 Years Ago
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charliemccraney (1/10/2009)
I just carefully remove the gasket with a razor blade.That is an excellant way to do it, may take a little time but why get in a hurry. Do it right!
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By pintoplumber - 16 Years Ago
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I have been telling My customers for years to throw these things in the craper.
Tim, don't do that, that just creates a whole 'nuther set of problems.
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By 46yblock - 16 Years Ago
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I never used the disk method of gasket removal until my trusted (formerly trusted) mechanic showed me how easy the disk made the task. This last set of heads I removed had been cleaned of material with die grinder, by me. I noted a number of areas on the head's deck surface that the gasket apparently hadnt sealed, and wondered why. Now I know.
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By charliemccraney - 16 Years Ago
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I've never used them. Now I may be glad I haven't. However, I wonder how many people read and follow the instructions. It would be interesting to see if the same poor results occur when the instructions are followed exactly. Don't push down on the disc, use a 2 to 5 degree angle, do not continue to abrade once the gasket has been removed, never use coarse discs, etc.
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By DANIEL TINDER - 16 Years Ago
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Tim,
Your comment re: "rolled combustion chamber edges" got me thinking. I had heard that when grinding/polishing chambers, the sharp edges left from milling should be smoothed to prevent pre-ignition/detonation. Sounds like a delicate compromise is warranted?
Your opinion?
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By 46yblock - 16 Years Ago
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charliemccraney (1/10/2009)
I've never used them. Now I may be glad I haven't. However, I wonder how many people read and follow the instructions. It would be interesting to see if the same poor results occur when the instructions are followed exactly. Don't push down on the disc, use a 2 to 5 degree angle, do not continue to abrade once the gasket has been removed, never use coarse discs, etc.Instructions  ?
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By mctim64 - 16 Years Ago
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pintoplumber (1/10/2009)
I have been telling My customers for years to throw these things in the craper.
Tim, don't do that, that just creates a whole 'nuther set of problems.Took me a minute, you are a plumber. I get it!
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By mctim64 - 16 Years Ago
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DANIEL TINDER (1/10/2009)
Tim,
Your comment re: "rolled combustion chamber edges" got me thinking. I had heard that when grinding/polishing chambers, the sharp edges left from milling should be smoothed to prevent pre-ignition/detonation. Sounds like a delicate compromise is warranted?
Your opinion?Daniel, it is good to take the "sharp" edge off the combustion chamber to prevent detonation, but what I was talking about here is the gradual roll that you can see when a strait edge is laid across the deck surface and slip a feeler gauge between the chambers. That's not good for holding a gasket. 
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By pegleg - 16 Years Ago
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mctim64 (1/10/2009)
Took me a minute, you are a plumber. I get it! Tim, If you ever saw the sign on the side of his truck "Leeking Plumbing" you wouldn't forget it!
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By Y block Billy - 16 Years Ago
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Why would Dennis Mind? thats job security for him. I would not use those disc on any flat mating surface, I have many scalpel sets around and razor blade scrapers made for that task. Although I use those disc for buffing welds smooth. I have dissassembled many items where gaskets were not available, so prior to separating the parts I go on each side of the gasket with a narrow pointed scalpel and make sure the gasket is free prior to separating the parts, I have saved many gaskets this way and if I am too lazy to make a new one I just coat the old gasket by rubbing it between my fingers with Motor honey, STP or similar product, that way it has a good seal and will not be stuck next time you need to take it apart. In making gaskets, if you do not have the proper hole punches and are working with tiny carb orifice holes and whatnot, you find some small tubing the correct size, install it in a drill and sharpen the end with a file. A round file or reamer and sharpen from inside works best but a flat file from outside may get you by but when you punch the hole it may tend to spread the gasket with the taper of the end. The scalpels work great for the bigger odd shape cuts. Always stone the surfaces flat if possible before reassmbly.
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By bird55 - 16 Years Ago
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cool, I learned some more stuff here.
Always used a putty knife or razor blade, but didn't know about the combustion chamber edge thing.
gots to be exxxxtra careful with my new aluminum heads. 
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