Head skimming tips & tricks?

[mole42]

I'll be taking my heads to the skimmers this week. They have done Stag heads before but is there anything I should particularly ask them to beware of, or anything that is good to mention before they wind the cut on? A brief measurement suggests that the heads will only need a light cut, I'm hoping that is all.

[jakesmig]

If there is anything you think you need to tell them they can't be much cop at what they do.

[SGN]

For what it's worth, I think you can't take anything for granted whoever is doing the work and you should be cautious, I would certainly mention the heads are close to the limit and to take off the least amount they can get away with.

Cheers
Steve

[new to this]

Did you have the heads skimmed on the last rebuild ?

Dave

[mole42]

Not the last time Dave, they measured flat on a faceplate. This time I'm being ultra-cautious and making sure the heads are flat by skimming as well as measuring the block faces for flatness. This time I had to encourage the heads to come off which might have left a little distortion to contend with.
Something encouraged a gasket to let go after only 25,000 miles and I would like to be sure I found out what it is. The BGA gaskets seem to be in good condition except where there is evidence of leakage.

As they say where I'm from - belt, braces and a piece of baler twine will stop your trousers falling down!

[flying farmer]

Where were the gaskets showing signs of leakage?

This is obviously the bit that needs closest examination.

I am surprised your heads needed encouraging to come off as all the previous examples I have come across, the heads just fall off. Unless of course the BGA gaskets have some sort of sticky surface which I have never come across before on Stag head gaskets.

Neil

[022Dave]

There's a consensus on here that, if an engine has a history of short head gasket life, check the block face for flatness. No amount of head skimming will make it better.

Dave

[mole42]

Where were the gaskets showing signs of leakage?

This is obviously the bit that needs closest examination.

No8 here looks a tad leaky....

Stag LH head.JPG

I am surprised your heads needed encouraging to come off as all the previous examples I have come across, the heads just fall off. Unless of course the BGA gaskets have some sort of sticky surface which I have never come across before on Stag head gaskets.

Neil

The heads were loose on the block, but both had a single stud that siezed in the head, I had to saw them off after using the rope trick to get anough room for the blade. Last time both heads came off without any trouble at all.

Desperate measures.jpg

I will be in the garage again this afternoon with my straight-edge and the feeler guages to check the block, especially around No8.

Richard

[richardthestag]

the only clusterf*** that my machine shop fell into was trying to skim back local corrosion on the head face which blank against the dead end coolant holes on the block.

Took a pair of heads with shed loads of life in them down to their last skim.

Unhappy was I

[mole42]

Ouch!

[mole42]

I'm fairly sure that I've found the source of the head gasket leakage:

Corrosion.jpg

Does anyone know a good TIG welder? The other head is nowhere near as bad as this.

I tried a quick check with a straightedge and a 2 thou feeler guage, I couldn't find anywhere near the rear of the block where I could get slide it under, I'll check further next time.

Richard

[wilf]

That does look a bit close to the fire ring, definitely worth welding up.

[flying farmer]

One of my spare heads looked a lot like that before I welded it up, but I haven't had it skimmed yet after I welded it.

Richardthestags experience with head skimming has always been my greatest fear, fortunately it has never happened to me!

I am surprised you had two head studs seize that hard after such a short period of time. Did you forget to use some sort of anti seize compound? I recently had to remove a head on my Estate as I couldn't remove the water transfer housing and that came off easily after nearly 10 years.

Neil

[mole42]

I am surprised you had two head studs seize that hard after such a short period of time. Did you forget to use some sort of anti seize compound? I recently had to remove a head on my Estate as I couldn't remove the water transfer housing and that came off easily after nearly 10 years.

Neil

I don't remember what anti-sieze treatment I used last time but it obviously wasn't good enough. What do you use Neil?

Richard

[flying farmer]

On the ones I have dismantled I used some of the copper grease stuff, but it does get rather stiff after 10 years.

For the last few years I have been using the ceramic grease used on diesel glow plugs but I haven't had the heads off any of these engines so I can't comment on its efficiency yet!

Neil