Valve Cover Coating Peeling Question

[Joshbot007]

Like many others the insides of my valve covers are peeling, and I don’t want that coating falling off and getting in my oil. I read many posts about this, but everyone says either to replace or recoat (usually outside and in via powder coat). Has anyone ever just had the inside blasted clean and left that way? I assume the inside coating is some temperature resistant stuff but is that really necessary or can I just leave it as bare magnesium in there? I cannot think of any reason why I couldn’t as I do not believe oil negatively reacts to magnesium nor do I believe it would start to corrode due to it being constantly coated with oil from the moving parts throwing it around in there. Any legitimate reason on why not to have it blasted down to the magnesium and run it that way?

[pbonsalb]

It won’t hurt anything. BMW magnesium valve covers have been flaking inside for 25 or 30 years.

[Joshbot007]

Originally Posted by pbonsalb

It won’t hurt anything. BMW magnesium valve covers have been flaking inside for 25 or 30 years.

It won't hurt anything as in removing the coating and running with bare magnesium or as in it's fine to just let it go as is? If it's the latter I agree and disagree. While it's likely not to it could get bad enough at some point the chips could (in theory) plug up the oil pickup or passages.

[OmairK]

So my E36 S50 (1995 only) also has a Magnesium valve cover, I noticed a very small amount of warping which lead to very minor oil leaks. I replaced the entire valve cover and no more oil leaks. In this case, whenever my VCG decides to leak or my valve covers start flaking, I’m just going to replace both covers or buy new powder coated ones from Future Classic.

[Joshbot007]

Ok this is all great but I am still wondering the answer to my original question. Can you or can you not strip the coating from inside the valve cover without any negative effects of having a bare magnesium cover on the inside of the engine? If there are any negative effects what are they? I can't envision any but I have been wrong before

[SYT_Shadow]

Originally Posted by Joshbot007

Ok this is all great but I am still wondering the answer to my original question. Can you or can you not strip the coating from inside the valve cover without any negative effects of having a bare magnesium cover on the inside of the engine? If there are any negative effects what are they? I can't envision any but I have been wrong before

the valve covers I had powdercoated had the inside just sand blasted, it was the outside that was powdercoated

I saw a friend's setup, powdercoated+clear coated exterior which looks very nice

[pbonsalb]

Originally Posted by Joshbot007

It won't hurt anything as in removing the coating and running with bare magnesium or as in it's fine to just let it go as is? If it's the latter I agree and disagree. While it's likely not to it could get bad enough at some point the chips could (in theory) plug up the oil pickup or passages.

If you want to worry about it, you can. Many cars have had magnesium valve covers going back decades. I have never read of engines failing as the paint flakes off. None of the thousands of people changing rod bearings have reported clogged pickups.

If you must have pretty undersides, media blast them, bake them to get the oil out, and leave them bare or recoat with something close to what the factory used. I think the paint helps protect the magnesium from corroding.

[SkiFly01]

If you remove the coating on the inside they will be fine, it won't corrode because it's going to be fully coated in oil unless you let the car sit for months at a time.

[pbonsalb]

That makes sense, at least for cars that are drive regularly.

The corrosion seems to be occurring under the paint, causing it to flake off. I was assuming the paint was out there for a reason since it would have been easier for BMW to leave the undersides uncoated.

[white_4door]

i havent had any issues yet, sandblasted my covers inside and out and only painted outside with high temp paint, taped off where all the seals go. i have put 3-4,000 miles on it since then

[Mpow-wow]

Seems retarded to have paint on the inside of the valve covers. 🤷*♂️

[wfdeacon88]

So reading this thread I don't think I understand how to take used valve covers and refresh them the correct way. As I understand it, no need to coat the inside, but what is the safest way to get the inside of the covers (I just bought a used pair for $200) clean? Do I tell the shop that's doing the powder coat to blast the inside with something? or like steam clean? I just want this to be a 'permanent' fix for me. I'm going to do wrinkle red powder coating on outside. here's the inside of the ones I just got for reference.

Thanks!

[Joshbot007]

Originally Posted by wfdeacon88

So reading this thread I don't think I understand how to take used valve covers and refresh them the correct way. As I understand it, no need to coat the inside, but what is the safest way to get the inside of the covers (I just bought a used pair for $200) clean? Do I tell the shop that's doing the powder coat to blast the inside with something? or like steam clean? I just want this to be a 'permanent' fix for me. I'm going to do wrinkle red powder coating on outside. here's the inside of the ones I just got for reference.

Thanks!

The shop I used dipped them in a solution (they were not sure if it was needed but wanted to be safe) then glass bead blasted them on both sides. It was a fine glass bead I was told as to not cause damage or surface roughness to the magnesium. After that they just powered coated the one side and where the gasket sits (the bare magnesium is actually very rough so a coating on the gasket area will help it seal).

As far as getting any powder coat on the insides, it's inevitable. That is unless you wanna pay tons of money to have them perfectly mask off everything. The little over spray that is in mine should be fine and it's not continuous enough to "peel" like the original coating. If anything a speck or two of powder might come off during the lifetime of the car and be easy picked up by the filter but I doubt even that will happen with properly bonded powder coat.

I had a local race and restoration shop to mine and I think they turned out good and Im confident in the work