Head gasket keeps blowing

Post by **smithwi** » Mon Sep 08, 2003 2:26 pm

Hi,

My head gasket has blown twice in the last year. I was wondering what might be to blame. There's no obvious crack/buckle in the head and the engine didn't seem to be overheating when it blew. I wasn't driving *too* fast - I generally try not to go above 60mph, not that it would go much faster

The last time the gasket was fitted the cylinder head wasn't ground - could this be worth doing this time?? Could it just have been a defective gasket or problem with the way it was fitted (I know it can be a tricky job). Anything else I should look out for? Don't want it to blow again in the near future!

Post by **Cam** » Mon Sep 08, 2003 2:37 pm

We have had reports recently of bad quality head gaskets. Try using a copper type one if you have been using one of the cheap fibre type ones before.

Also it's worth getting the block face checked as well as the head.

If the block face and head are OK and you use a good quality gasket and tighten it down correctly, then there should be no problems.

Post by **Kevin** » Mon Sep 08, 2003 3:38 pm

As Cam said there have been a few problems with the non copper head gaskets, the correct ones are only around £10:00.
you can check the head yourself if you have a piece of plate/float glass and some engineers blue, you just spread a thin layer of blue on the glass and slide the head across and it should have an even coating of blue if there are areas with none on it you will need to get it skimmed, also the head bolts should be tightened in the correct sequence and make sure the push rods go back in the holes they came from.

Post by **rayofleamington** » Fri Sep 12, 2003 1:18 pm

Copper head gasket £4.95 from Bull Motif
01386 831755.
Or you can pay about £10 for one on e-bay

An engine machinist can check the head for you, and if you watch them carefully you may be able to repeat the test on your block - It can be done withs a strong flat steel bar and some feeler guages (I think..)
That can be a bit less skillful and messy than the engineers blue.
I tended to have mine skimmed anyway if doing a rebuild to avoid any risk.

Post by **Kevin** » Fri Sep 12, 2003 2:17 pm

It can be done withs a strong flat steel bar and some feeler guage

Only providing the bar is true and ground flat

That can be a bit less skillful

I should think so
If you are not sure or know how to do this just ask a workshop to check it for you, or ask a friend who works for an engineering company.

Post by **rayofleamington** » Fri Sep 12, 2003 7:44 pm

Only providing the bar is true and ground flat

Yes - I should have stressed that. You can of course use the sheet of glass to check the flatness of the bar. Most engineering workshops will have a nice flat bars, but as kevin mentioned, if you are unsure, ask someone who's a bit more experienced.
Don't use an old sheet of glass, as glass changes shape under it's own weight over time... Then it won't be flat.

Post by **Kevin** » Sat Sep 13, 2003 11:55 pm

Don't use an old sheet of glass, as glass changes shape under it's own weight over time

Forgot to mention that, I was amazed to find out many years ago that old glass is semi fluid in structure and sags/runs with age, because if you measure glass in an old window its thicker at the bottom than at the top although when put in it is the same thickness, I am sure some law of physics must apply here, I will have to ask my daughter maybe the princepal applies to other things as well.

Post by **paulg** » Sun Sep 14, 2003 10:06 am

I remember being taught that glass is a "supercooled liquid" and that is why it "flows" and reacts to gravity. It is a bit of a slow flow 'though!