Cylinder head surface machining(home remedy)

[dom14]

These are the photos of my bench machining setup & the job I partially finished on the RB30 head.

Can you guys have a look at the photos and advise me whether I need to machine it further?

I'm particularly concerned about the pitted/porous surface around few of the water jacket lines(see photos).

I used 320 grit wet sandpaper with a bit of WD40 sprayed on it to machine the cylinder head surface.

[dom14]

The surface finish came out pretty good(smooth and even without much of visible lines from sandpaper) when I combined the sandpaper with WD40(wet/oily sanding).

The cylinder head is pretty straight and not warped at all.(Even with 0.05mm feeler gauge), so the reason to machine is basically to remove the markings left from the old head gasket. But, I realized how important to machine a cylinder head even if it's not warped. There are numerous areas of pitted surface, particularly around the water jacket lines. It is not possible to see them without machining the head.

I am also wondering what is the requirement about the surface finish of a cylinder head.

I mean, is smoother finish the better???!! Or is there a requirement for a particular texture??!!

I can get a really smooth finish by combining even smoother sandpaper with a wet spray like WD40, but I don't know the perfect smooth surface is a requirement or a hindrance for the best head gasket seal.

[GQtdauto]

You've done fair sort of a job Dom, personally the pitting and corroded bits look bad but some of the corrosion is full thickness by the look of it so not sure how you'll get around that .

[dom14]

You've done fair sort of a job Dom, personally the pitting and corroded bits look bad but some of the corrosion is full thickness by the look of it so not sure how you'll get around that .

Hi mate,
Not sure what you meant by full thickness of the corrosion, but yeah it is a concern.
I guess, to get rid of the porosity near few of the water lines I would have to machine it bit more, perhaps 0.1mm or so.
There is enough thickness in the cylinder head, so I don't think it would cause excess compression issues.
Bit of sanding for sure.

[dom14]

I wonder if there's a some kinda super thin paste that I can apply around the pitted water lines to prevent any water getting through them in the future.

[GQtdauto]

One or two of the water galleries in the pic aren't original shape , they look eaten away by corrosion so to me it looks like full thickness of the metal eaten away but it might just be the pic .
You can get different thickness head gaskets and I'm sure I've seen you tube vids on repairing cracks and corrosion .

[dom14]

One or two of the water galleries in the pic aren't original shape , they look eaten away by corrosion so to me it looks like full thickness of the metal eaten away but it might just be the pic .
You can get different thickness head gaskets and I'm sure I've seen you tube vids on repairing cracks and corrosion .

Yeah, eaten away a little bit, but not too far from the hole I reckon. My existing head had corrosion on water gallery holes that you wouln't wanna see.
Yeah, I reckon I can get a head gasket that is thicker(after machining the head bit too much) to get the compression back to normal range.

I've seen youtube videos of crack repair, but none that is doable at home.
If there are any cracks , I would have to get it professionally repaired, but so far it doesn't look like there are any
cracks(or at least cracks that leak oil to water and vice versa).

I'm wondering whether there is a way to fill the porous surface around few of the water galleries as in the pictures.
Something similar to thread sealant.

[bazzaboy]

Usually, if I have a head that shows that degree of corrosion on the water galleries, I get it checked for microscopic cracking. It's a real bugger to recondition it only to have it fail 3 months down the track. Been there, done that.

[dom14]

Usually, if I have a head that shows that degree of corrosion on the water galleries, I get it checked for microscopic cracking. It's a real bugger to recondition it only to have it fail 3 months down the track. Been there, done that.

Most places do pressure testing, but not the more expensive "ultra sound", "x-ray" type of crack testing for structural issues that don't show up as water to oil or vice versa issues.
There are no cracks in the combustion chamber areas, but I'm not sure about any cracks that may be hiding and will appear as water to oil/oil to water leakage in future. I guess I'm gonna have to deal with that later if that's an issue. Most heads do carry that risk I reckon?!!

If I can find a solution for the porosity around few of the water galleries without having to machine it too deep, I'm ok with that.
By "solution", I didn't mean the stop leak stuff that we add to the coolant, but rather a some sort of long lasting(not forever:) ) filler/liquid sort of thing that I can thinly apply to the porous area around the water galleries.

I'm thinking Loctite Red.

Any thoughs???!!

Thread sealant hardens in the absence of air, so I reckon it should be a good filler for those tiny pitting around few of the water galleries??!!!

[dom14]

This is the crack repair that I can do at home if I can get hold of those aluminium crack repair "studs".
But, it's not necessary in my case anyway, 'cos there are no cracks of that kind by the looks of it.

https://www.youtube.com/watch?v=P4cGvYBb9Ag

[billyj]

being an aluminium head its very important to have it crack tested and also hardness tested, doesnt matter how flat or perfect the head looks if its gone soft the gasket will fail again before long

[dom14]

being an aluminium head its very important to have it crack tested and also hardness tested, doesnt matter how flat or perfect the head looks if its gone soft the gasket will fail again before long

I haven't had it hardness tested yet mate, yeah definitely will take both heads to the local head guy to have them hardness tested before either one of them going on the block again.

Thanx.