Blown head gasket

[ROGER B]

The head gasket of my standard 1098 Traveller 1970 has blown between cylinders 3 & 4. I am planning to have the head lightly skimmed to ensure it's flat, fit a new gasket and correctly torque up the head. I will do whatever is necessary to the valves while the head is off. Is there anything else I should do - perhaps apply a high temp sealant? The gap between 1&2 and 3&4 is much narrower than 2&3, so this might be a weakness and I can envisage this happening again, and would like to do whatever I can to prevent that. Thanks for any advice.

[myoldjalopy]

My view is that as long as a good gasket is fitted and the head is torqued and then re-torqued as necessary, no sealant is required and may even be counter-productive. Recommended to grease the gasket before fitting though.
Unfortunately, head gaskets do blow from time to time and that is just the way it is.

[Myrtles Man]

Unless it's been done already you may decide that having hardened valve seats fitted is a good idea too.

[svenedin]

There are lots of things you can do to ensure you get a very long life from your new head gasket. I think most of it is in a thread where I was asking for advice having never done the job myself (I'll try to find the thread).

In no particular order:

1) Try to ascertain why the head gasket blew in the first place. Did the engine overheat first for example? Were the studs loose? Does the engine have a history of blowing gaskets (suspect the head and or block are not flat)? Look for "pulled up threads" where the studs go into the block (this is where the thread in the block gets pulled up by the tension in the stud and is easily sorted by the home mechanic by light countersinking). Was it just a cheap nasty head gasket?

2) You need to check that the surface of the head and block are flat. There's lots of knee jerk responses about "needs a skim" but these are cast iron, not aluminium alloy and they probably are flat provided the engine didn't run with the blown gasket or seriously overheat.

3) Ensure the mating surfaces are surgically clean. I found a window glass paint scraper worked very well (a Stanley knife blade in a plastic handle). Unless you are silly, it is hard to scratch catch iron. Lots of WD40 or PlusGas acts as a lubricant and you can use Green pot scourers too. Stuff rag in the bores so the crud doesn't go in there.

4) Use a top quality copper head gasket. ESM sell a copper head gasket but the premium gasket from Minispares is thicker and seems better made and more sturdy. https://www.minispares.com/gug702506hg- ... minispares

5) Consider getting a set of high tensile studs and flange nuts. These can take a higher torque than standard.

6) No sealant is used other than to lightly grease both sides of the head gasket.

7) Obviously follow the workshop manual and tighten the stud nuts in the correct sequence. Get a torque wrench. Remember to re-torque the nuts after a run out up to full temperature. You will have to re-check the valve clearances too.

8 ) Consider replacing the thermostat and thermostat housing gasket at the same time since with your late car, the heater pipe bracket is under two of the head stud nuts.

9) Consider changing the rubbers on the engine steady bar if necessary as this is also retained by a head stud (note the stud is longer).

10) Remember a heater valve gasket and manifold gasket. What I did is to buy a "de-coke" gasket set which includes all the gaskets you need but used a better quality head gasket than the one in the set.

There's loads of tips here but it's a long rambling thread: viewtopic.php?t=76095&hilit=head+gasket

Stephen

[ROGER B]

Many thanks for all the helpful and detailed replies. I have spoken with Minispares who say they usually sell this even better gasket by Victor Reinz, but are out of stock https://www.minispares.com/gug702506vr- ... ead-gasket. So I think I will do the best I can with the Minispares gasket recommended by Stephen.

[ROGER B]

What about one of these which the seller describes as the best composite gasket on the market, but that stops short of saying it IS the best gasket!?

https://www.ebay.co.uk/itm/186978510533 ... R_DAqZalZQ

Gosh, that's a long link, hope it comes out!

[svenedin]

I don't have experience of the composite head gaskets. The copper head gasket on my Morris lasted 34 years and even then it didn't 'blow" it just started leaking oil quite sedately.

Stephen

[myoldjalopy]

Opinions will vary, but the copper gaskets are generally held to be better than composite ones. The one in Stephen's link would be fine, I am sure.

[philthehill]

The Mini Spares copper gasket in the link above https://www.minispares.com/gug702506hg- ... minispares is more than suitable for small bore engines.
There is no need for a composite head gasket.
I would suggest that you lightly countersink the stud holes in the block and fit 'A' Plus cylinder head studs with flanged nuts. The studs can then be set to 50lbf ft torque. Lightly grease with GP both sides of the head gasket before fitting.