Working around galvanic corrosion on the cylinder head.

When I took apart the newer engine with 70,000 miles I found a small amount of galvanic corrosion on the head near the front water passage under the original gasket. I've seen this happen with steel gaskets between aluminum parts (dissimilar metals) that are exposed to engine coolant. It happens. Not a new problem.

I usually like to stay with OEM gaskets except in the case where I have to correct some surface integrity issue or I'm dealing with Subaru. Ha! In those cases, FelPro gaskets with the blue silicon seals help fill in and prevent any further opportunity for corrosion or leaks.

So I had already purchased OEM gaskets and decided not to use them.

Here's a picture of the pitting that occurred and the gasket that I'm using to keep the problem from returning.

 

So I'm assuming the OEM gaskets have steel or something around the coolant ports where the pitting is?

 

The ones I removed were steel with a black looking paint coating. I was surprised to see that at 70,000 miles. Since I've seen this before, I just pitched them in the garbage and moved on.

Nissan V6s have this issue with an aluminum coolant crossover pipe that runs between the heads. The factory gasket is steel. As it ages, galvanic corrosion sets in and causes pitting on the mating surface. Some times you can sand it away, and sometimes you can't. Many years ago, I accidentally bought some FelPro gaskets for a V6 project and found the silicone seal. It looked to me like FelPro must be talking to the shops and designing in product enhancements to deal with some of the issues that happen with older engines.

 

it might not be that only.

 

Excellent info. That is something to check. I like to increase engine grounding. I actually replaced the ground wire that ran from back of the engine to the firewall with a battery cable gauge lead. I would like to look into beefing up grounding. Some of my other car clubs have members that sell grounding kits.

Interestingly, and without knowing, I've added additional grounds to the engines where I found the issue.

 

So are you just replacing the gasket and hoping there are no leaks afterward? If it was me I'd get that machined before putting everything back together. I had to take a head off twice because of this..

 

Its already back together and running. No leaks so far.

 

Me and the wife had a 81 olds station wagon back in the day,,, long time ago,,,. It had a 305 in it and was one of the first "computerized" cars of it's time, electronic carburetor of all things. It had a aluminum intake and would start corroding at the water coolant passage on the head (cast iron) to the intake on the drivers side front corner. The corrosion would grow and start separating the intake, actually pushing up,, and then leak. I had to replace the gasket about every 60 k miles. Did it 3 times if I remember right. Electrolysis is what I always heard caused this, above my pay scale.

 

If I had an issue like that I would try jb weld, let it cure and sand down to the surface. I've seen youtube videos of jb weld being used in that manner and I think it might just work.

 

If it gives and trouble, I will give that a try. So far so good with the silicone seals.

 

I think, again, i think the supposed fix is to change out the coolant every two years to keep the electrolysis from getting started. It'll actually start a electrical charge in the coolant which starts the whole thing.

 

Yep. Im good about changing coolant and running extra grounding. Im always reversing damage from a previous owner.

 

So I was under the impression it was running good already, did you have a coolant leak or vaccum leak by chance? I really dig the felpro stuff especially the cardboard style gasket, that lip was something I used to screen print on copper head gaskets for SCE gaskets when they were in Lancaster,CA. I miss the days of giving my friends free gaskets and taking what I needed, we had tons of copper I could have made about 500 liquor stills, lol, the family were moonshiners from Tennessee.

 

I had this issue with the water passages on my VG30E, that has a water passage next to each intake runner so the opportunity to leak is pretty large. I used classic rubber and steel gaskets and coated each side of the rubber portion with Blue Hylomar and it's been leak free so far. Next time I have it apart I'll probably block sand the ports to make em smooth and pitless again.

 

It's running great. I was reflecting back on the build and the reason I've been using those FelPro gaskets for all these years and how I accidentally found they solved a problem that I called "gasket rash". I didn't know if this was common on the 3.4 so I posted about it. When I saw it I just said. Meh. I know what to use here.

 

I think every VQ30 that I've refreshed had it at that location. I haven't had it leak with the silicone gaskets . Life goes on.

 

That means some of your kin folks had a Rocket 88. Hehehe.