Minor pitting on Cylinder head

Anyone ever have issues with using a head having this minor pitting?

If there’s enough meat to have the mating surfaces milled it should be fine. Good photo, but I can’t tell from it.

I’m guessing that’s where the antifreeze contacts the head - is it?
Make? Model? Year? Miles? Why did you remove the head?

That pitting is between two water jackets of the head/engine.

I’d install the head/gasket and never give it another thought.


The reason its pitted is from my stupidity of trying to use electrolysis for cleaning. Don’t ask, I’m dumb sometimes. It’s a 2005 Mazda 3 2.3L . I bought it cheap to rebuild the engine, cylinders 1 and 3 had no compression due bent valves, timing chain issue. The pits are so little depth that I can’t measure them

I’ve read others scraping on JB Weld or the “DIY decking” with a piece of glass as the “true” surface and sandpaper glued to it. I’m going to phone tomorrow and see how much milling is, but I was hoping non of that would be necessary. Guessing I’m wrong.

I have used spray Copper-Coat on head gaskets when there was an issue with sealing the water jacket but when the compression sealing ring on the head gasket will be mated to a rough surface on the head I would be troubled.

The seal on a head gasket for the cylinders is called the fire rings.


There’s no way I would accept that surface on the head of a modern day engine. For the few beans it would cost to resurface that head I wouldn’t do it any other way.

I’d have to agree with @asemaster on this one. You’ve got the valves out so it’s ready for machining. Play it safe.

Yep no good option besides getting it surfaced by a pro.

I suppose there’s no harm done to try to sand those blemishes out using a thick piece of plate glass as the backing for the sandpaper. I’ve never had to have a head surface machined flat, but I wouldn’t expect it to cost much. If you’re worrying that if you take it to the machine shop they’ll try to get you to do other stuff to send up the bill, well, you may have a point there. If saying “no” isn’t your thing, go with the sanding I guess. Or just try it the way it is, don’t do anything. I’ll bet it will work ok without doing anything.

There’s no way I’d install a cylinder head in that condition. Around here anyway, surfacing a head is about 40 bucks and it’s money well spent.

A flat piece of tempered glass and emery cloth will smooth it out but that’s going to take a lot of elbow grease and will likely lead you to wonder why you didn’t just have the auto machine shop surface it and be done with it.

Making a mistake while using electrolysis does not mean that you’re dumb. Just consider it part of the learning curve.

One other thing did come to mind. What effect did the electrolysis treatment have on the spark plug hole threads?

You need to inspect those very carefully on the offchance that the threads were eaten up a bit and weakened. That could lead to plugs stripping out or getting blown out while the engine is running.

I would also hope that the camshaft saddles were not eroded due to the electrolysis. If so, it may be time to go head hunting… :slight_smile:

Thanks alot for all the replies. First forum I’ve found with great responses and it’s really appreciated. Definitely going to do some closer inspection and hopefully it’ll be less then $75-$100 to get it decked if I don’t need to go head hunting.

Gotta enjoy those learning curves.

I’ve done electrolysis thing with rust removal, chrome removal, etc and the learning curve on chrome removal snagged me a bit.

There was an antique motorcycle part that had been chromed and chrome was an option at the time. I wanted the non-chrome option so I chose to remove it by electrolysis.
In spite of using extreme care and keeping the electrical current down I damaged the part by leaving it in the solution too long. The chrome was stubborn about coming off and the extra time I allotted ate up the edges of the distributor cover; essentially making it a display piece and useable on a bike only if looks and keeping water out was not important. sigh

How were you cooking that thing?why did you think electrolysis,was the way to clean something like that?A rebuilt cylinder head may be the way to go.

I’d play it safe and get a full work up at a machine shop: mill the head, clean up the valve seats, lap the valves, check the valve guide clearances and replace if needed

Good point, @circuitsmith - there are lots of areas that would be damage by this. It’s a DOHC head - what about the bearings, etc?