Gasket Surface Cleaning and Prep

[mercurymang]

I may be making too much an issue out of this but I thought I would throw the question out there and see what comes back. I plan to be putting everything back together on my merc in near future and am at the stage where I need to clean up all the mating surfaces in prep for new gaskets. What is the best method to get off the old material. A razor blade tends to dig into the aluminum. I have actually tried block sanding and it seems to work pretty well and it allows you to see if you have any high/low spots. Anyone have any advice on this?

 

[Maxz695]

Re: Gasket Surface Cleaning and Prep

pretty much waht I did all day today. Block sand the exhaust port for the baffle as I was after the rebuild getting water in the engine causing missing. I took a peice of OAK 8 X 14 and glued medium sandpaper to it with a spay adheasive I have. I then used a finer sandpaper and it came out nicely. Problem is I sanded the outter cover that was apperently warped but i did not sand the inner ridge for the smaller gasket and it drips out of the boltholes. I,m going to take the cover back off tommorro and hit the inside some to even the case off. I did not use gasket sealer as I have been through 4 gasket sets trying to get it to seal and keep water out of the engine. Torquing the cover with sealer can cause the gasket to spread and break. I may use a slight bit when re installing the outter cover though this time due to the uneven ridges of the inner (small bolt holes) and outter surfaces.

 

[Faztbullet]

Re: Gasket Surface Cleaning and Prep

I bead blast my customers clean, leaves it nice and clean, no warps, and a little surface friction so gasket doesnt slip. Works great on transfer port covers!!!!

 

[mercurymang]

Re: Gasket Surface Cleaning and Prep

I can see bead blasting of disassembled parts but not sure I would want to bead blast an assembled block with the potential for getting that stuff everywhere. I'm pretty sure you know more about it than me though so you must have that process down. At any rate, I don't have a bead blaster but I'm thinking a wire wheel is my best bet.

 

[Maxz695]

Re: Gasket Surface Cleaning and Prep

I used tin foil in the exhaust cavities to keep out the remnants when sanding mine. Use a couple of layers to help protect the ports. I then hoesed it down to remove the aluminum particals. then carefullt removed the foil and wiped the surface with a dry rag to make sure nothing remained. As I stated earlier no gasket sealer on the inner gasket for the baffle to block and it ran good. You did the right thing in getting the new outter cover though. Does your manual call for using sealer on these areas? I had to use it on the outter cover and will test it out later on today.

 

[Texasmark]

Re: Gasket Surface Cleaning and Prep

When you finish with all the above and get the surface clean, like using aerosol brake cleaner; cheap, has a good blast of liquid, doesn't damage paint, degreaser, and evaporates fast with no residue, a good coating of Zinc Chromate primer would do wonders to prevent future problems. Zinc Chromate is used for preserving aluminum surfaces and actually chemically etches the surface making a deliberate (thin) layer of corrosion to prevent future corrosion. Probably the inside of every aircraft of any size or use has it. On military aircraft it is clearly visible. Krylon makes it in the rattle can which is what you want....easy to apply a thin layer. If you can't find it go to an automotive paint store.

Mark