Blown head gasket ???

[Whatty]

Need a second (or even a third) opinion as to whether my head gasket has blown.

After a rather spirited drive on Sunday I noticed a steady small whisps of smoke/steam coming from somewhere behind or between the inlet manifold/cylinder head/rocker cover, couldn't see exactly where. The car showed no signs of overheating, the rockercover cap was clean however the oil level seemed quite high on the dipstick and while the coolant was to level it looked a little odd, emulsion I guess.

Its a 1968 998cc +20thou with twin SU's, improved manifold etc. The P/O rebuilt the engine about 9 years ago and I doubt the head has been off since. I'm guessing that long periods of inactivity together with my heavy right foot have caused this?

Edited by Whatty on Wednesday 25th November 13:14

[jammy_basturd]

Did you notice any difference in it running? Coolant look like it has oil in it at all?

Most probably the rocker cover gasket has a slight leak, which is leaking on to the hot exhaust manifold, causing the slight wisps of smoke.

[Whatty]

As I said in my previous post the coolant did have a slightly emulsified look to it.

I'll check the rocker cover gasket as you suggest.

Car seems to run well, recently fitted stage 1 kit and twin SU's have made a big difference but I think it seems to run out of puff after 60mph. I've got a 12G295 to go it which I'm hoping will help further. New gasket then anyway!

The photo shows why I had my right foot flat most of Sunday.

[jammy_basturd]

Well if you really suspect the head gasket then either try to do a compression test on the cylinders, or even better a leak down test. Any decent garage should now also have the equipment to test for exhaust gases in the coolant as well.

As a side note, I'm assuming you've had the car tuned and set up since you fitted the twins and stage 1, and also checking the compression ratio and combustion chamber size before fitting the 12G295 (by standard you'll get a really low C/R and thus poor performance). Sorry if I'm teaching you how to suck eggs.

[Whatty]

jammy_basturd said:

Well if you really suspect the head gasket then either try to do a compression test on the cylinders, or even better a leak down test. Any decent garage should now also have the equipment to test for exhaust gases in the coolant as well.

As a side note, I'm assuming you've had the car tuned and set up since you fitted the twins and stage 1, and also checking the compression ratio and combustion chamber size before fitting the 12G295 (by standard you'll get a really low C/R and thus poor performance). Sorry if I'm teaching you how to suck eggs.

You carry on teaching, I am the cheque book wielding kind of car guy, not the spanner waving sort! I really should learn a bit more and get my hands dirty.

The upgrade to twins and stage 1 was done by a MG shop.
I was going to send the head out to a shop in California to be skimmed/ported etc prior to having the MG place fit it. The US is a bit of a challenging where Mini's are concerned.

[jammy_basturd]

The 12G295 was meant to have been fitted to the Cooper, with domed top pistons. Most engines either have flat top pistons or slightly dished pistons now, which means the compression ratio will be really low (great for forced induction). If you are going to get it skimmed they are going to need to know what cc your pistons currently are, and what C/R you're planning on wanting.

[Cooperman]

It does sound like a head gasket.
Not a difficult thing to change, just make sure you get a good quality one.
If you feel the head needs a light skin almost any machine shop with a horizontal milling machine could do it.