Blown Head Gasket

[callmekay]

Hey guys,

I blew the head gasket on my 91 MX5

Was just wondering where the best places to buy a replacement would be, and any advice and tips you have on what I should be replacing.

I was thinking of doing the timing belt and water pump as well.

But if it all adds up maybe it would be better to buy a new head?

Is mx5parts.uk the best place to buy the parts?

Additionally, if anyone knows of someone selling the parts that would be awesome.

Thanks!

[93_Clubman]

See manga_blue's post here:
viewtopic.php?f=18&t=67144&p=833119&hilit#p833119
And Rolley's post here:
viewtopic.php?f=18&t=67144&p=833298&hilit#p833298
This is also useful:
viewtopic.php?f=18&t=65358

[hks_kansei]

Parts wise just get the gaskets from repco etc, often it's cheaper to buy a whole set rather than just the ones you need.

if money permits, you may as well do the timing belt and waterpump, since you need to remove the belt anyway to do the gasket.


A replacement head isn't really needed, since any replacement head may just be as bad as the current one. And the labour in having a head reconditioned isn't cheap.

I would check it with a straight edge to make sure it's not warped, if you arent able to do that yourself take it to a machine shop and they should be able to check it, and even better, give it a skim to make it flat again. The cost of a head skim shouldn't be too bad.

[93_Clubman]

But if it all adds up maybe it would be better to buy a new head?

Perhaps you mean another engine?

Not that there's a need, but even if you could find a brand new head, it would just be a bare head & you'd still need to buy all the other stuff. Have seen the very occasional supposedly brand new head or block for sale overseas, but I can only recall one on here, & it might have been a block & not head. Vaguely recall that it might have been myredmx5 - perhaps try PMing him: memberlist.php?mode=viewprofile&u=9701

[manga_blue]

The head must be checked for softness and straightness before you even think about re-using it. It takes a fair bit of heat to warp a head enough to cause the head gasket to fail. The metal may be permanently (and irrepairably) softened in the process. Take it to a machine shop. It must get a skim anyway. Any reputable place will test it for hardness before they book it in for the skim. It only takes a few seconds, it's free and they normally do it on the counter.

[sailaholic]

The head is aluminium so chances of it being irreparably softened is very very small, it's just that the cost of re heat treating is generally more than the cost of a salvaged head for a common engine. Unless you've spent lots of money on head work.


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[manga_blue]

Yes, I should have said economically repairable. You can do anything with unlimited money.

As an example though when I blew a head gasket at Winton a few years ago I took it to Reflex Engineering at Campbellfield outside Melbourne. The hardness test found it was down to 55 near the exhaust ports. They said I needed 100+ for a track motor. They then sourced 4 more BP05 heads from around the country which all failed at 50-60 before we turned up a good one. I still appreciate how much effort they went to for me for no charge.

[Caffeine]

The head on my car was too soft to be reused as well. I bought a replacement from MX5Plus.

I'd get it hardness checked as the first step.

[StillIC]

They then sourced 4 more BP05 heads from around the country which all failed at 50-60 before we turned up a good one.

I am so glad to hear that story. I have purchased 5 second hand B6 heads, from which I have one which is marginal for hardness, the others all being too soft. I did buy a new old stock B6 head from myredmx5 a few years ago. Man did that ball bearing bounce off the face! Night and day in hardness between it and every second hand head I have tested.