8 replies to this topic

[Mrpeanut]

I had my mini serviced a couple of weeks ago. It's a 998 with sw5. I asked for tappets to be set to 15 thou. After 30 or so miles the head gasket blew between cylinders 3 and 4 - the compression dropped to 20 on those pots. Suspecting possible valve issues I checked a tappet on cylinder 3 and 4. Both were 8 thou. I've whipped the head off and the gasket has blown (half inch of gasket gone) between 3 and 4.

Could the blow be a coincidence or linked to the over tight tappets?

[ukcooper]

I allway's found it was a coincidence when the head gasket went and messed with the engine-service that y I always do them my self.

 

besides you will never know or prove it .any chance you had would have been to take back as soon as it went wrong..

[Mrpeanut]

Yeah, I know. It was sheer laziness on my part but now the head is off I'll fit my 295 head so no big deal. It's more an issue of whether there could be a link. I thought there could have been a burnt valve but don't think that's the case.

[sonikk4]

One of those things that happens. Coincidental thats all.

[Mrpeanut]

Cheers guys. I've only ever had blows in between 2 and 3 and had understood that a blow out wide usually points to an underlying problem. Is that not the case?

[carbon]

Worth checking the block face is dead flat when the head is off.

[sonikk4]

It could have just been a poor gasket. I would run a straight edge over the face of the head and block just to check.

[racingbob]

What's the best head gasket for the 998 also what is the depth of a 295 head is it the same as 940 2.75

[Cooperman]

The standard 295 head is 2.75" deep, but the chamber volume is 28cc on a 295 and 24cc on a 940 (nominal)
A 295 needs to be skimmed to the correct volume and it is best for a 998 to have flat top pistons with a 295 head.