Head gasket failures - why so many?

[rip]

replaced leaking water pump a couple of months back.

Most of that hard work involved with getting to that will have to be repeated to get to the HG

[chris.t]

Sorry to hear that Mark but i had my suspicions that night at the H&C. If the head doesn't need to be skimmed then Steve should be able to have you back on the road fairly quickly although some skim the head as a matter of course these days.

[Specky]

- I'll keep my fingers crossed that it doesn't arrive until after he's done my head gasket then

Aye aye cheeky...

TTFN

[Jackonicko]

- I'll keep my fingers crossed that it doesn't arrive until after he's done my head gasket then

Aye aye cheeky...

TTFN

And you can both wait until he's done my fans!

[markv]

I think we should be prioritised on the basis of how much work we've previously put his way..... and on that basis I win hands down

[chipp]

add another one to that list

chipp

[bratboy_y2k]

For those thinking the HG problem is average on these cars, their wrong. They go on Isuzus very frequently with low milage. It seems to be a combination between low torque on the head bolts with a crap head gasket. The guys on the isuzone site are getting a group order for a steel HG. Imagine Owning an Isuzu in the 80s. It was basically an economy car that the gasket would go prematurely. Then the thing would cost a mint to replace because of the crazy way they were put together took a lot of time to work on.

[HJ2]

low torque?
Will re-(over) torque do any good on a still good headgasket then?

[DeeAitch]

:( add another one to that list

chipp

Make that 2

At least Lotus seem to have topped up on their stock of Gaskets

[bratboy_y2k]

low torque?
Will re-(over) torque do any good on a still good headgasket then?

not sure about retorquing the head bolts. If you look at the factory numbers they are quite low plus the material of the gasket itself is just crap. they go way more often then other gaskets. there are way toyotas and hondas running around with way more miles on them with no hg issues. it sucks.

[racerstev]

The head bolts are really big compared to most, 12mm is huge. It's really the gasket that's
the problem.

This will fix the problem, multi layer steel.

[rip]

This will fix the problem, multi layer steel.

I've heard that MLS gaskets are really good but are pretty unforgiving about the condition of the block & head so these need to be REALLY smooth before the gasket is fitted.

[racerstev]

I've been told the same thing, but saw some pretty bad surface's get sealed with them on other
engines.

I had to remove .005 from the block and .004 from the head to make mine perfect.

Steve

[bobbrown]

That's not an unreasonable amount to remove, 0.127 mm and 0.1 mm when you have more to play with, hope the surface finish (RA) was good as some shops have a problem getting good surface finishes but thay may be more historic as there are more and more cars now using MLS gaskets.

Bob

[DeeAitch]

:( add another one to that list

chipp

Make that 2

At least Lotus seem to have topped up on their stock of Gaskets

Well that has to be the worst job I've ever undertook on any car fitting a Quaife was a doddle compared to that The man who decided an earth strap was required on the back of the plenum should be shot but that was only one of a few things that I cursed.
Very surprised at how little bore wear there was but the top of the pistons horror. Took a full day to clean them up
And now my back is cattled
So now the dilema - do I re torque the head bolts or fingers crossed? Part of me says no harm in doing it, easy enough to do - but another parts says it was never re-torqued 20 yrs / 140k miles ago.
Opinions?

[Specky]

I'm gonna do a check torque, just for piece of mind.

I know what you mean about that earth strap, I saw the problem before it occurred, thus connected it before the head was fully lowered, but I got rumbled by the bolts in the PAS Pipe bracket at the back, they took an age to line up.

TTFN

[RayD]

... do I re torque the head bolts ... Opinions?

If there’s a particular application where it’s been proved to be a good thing then fair enough … But generally speaking it’s not something I’d do.

More importantly I’d avoid the method involving slackening the bolts off first.

Ray

[Brit-Car-Nut]

Actually, it is quite possible the head WAS retorqued during the PDI (Pre-Delivery Inspection).

All the MGs and Triumphs were supposed to be retorqued and I found that those that were had far less issues later on.

TVR also wanted their TR6 heads retorqued.

I say that because I was in a city with 2 MG dealers and the other dealer never did the retorque while we did.

They also painted the mechanic's initials on the radiator after the PDI as a sales gimmic.

A lot of those car ended up at my shop a few years later with head gasket leaks and cracked heads. They were good for my business.

[Brit-Car-Nut]

If you don't slack the bolts first, then you never get the right torque as the static friction fakes out the torque wrench.

Untorque the entire head in reverse order - just get below the proper torque, don't take the bolts out. About a 1/4 turn will be OK.

Make sure the head is at the correct temp - some mfgs want it hot, and some want it dead cold. You might want to put a little oil around the bolt's head so it doesn't "stick" to the head.

I usually go to each bolt and back off about 1/4 more and then bring it around to 80% of the torque and then go to the next bolt. Go around again and go directly to 90% followed by a final pass to 100%.

You are setting the tension of the bolt, not driving it into a blind hole until it bottoms out. The torque value is the proper amount of pressure to pull the head down to the block.

I am sure Bob B. can explain exactly what is happening when you torque a bolt.

[RayD]

Actually, it is quite possible the head WAS retorqued during the PDI (Pre-Delivery Inspection).

John, it is much more likely that it wasn’t.

All the MGs and Triumphs were supposed to be retorqued and I found that those that were had far less issues later on.

TVR also wanted their TR6 heads retorqued.

As I said … If there’s a particular application where it’s been proved to be a good thing then fair enough …

If you don't slack the bolts first, then you never get the right torque as the static friction fakes out the torque wrench.

I agree with you … it’s a good enough reason not to do it.

Ray