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Blown head gasket
Posted: Tue Oct 18, 2005 11:26 pm
by millerman
I have had a 70thou head skim and this head is fitted to a 1098cc engine with 20thou oversize bores. New copper head gasket fitted in july this year , 1800 miles ago, Payen I think. Head was retorqued to correct figure 100 miles after fitting. I usually aim to keep up with traffic at 65 - 70mph.
Anyway gasket blew between 3 and 4 cylinders today.
Advice required on how I can get the head gasket to last longer, torquing after 1000 miles,I suspect, would have helped. Are there any heavier duty gaskets that will maybe give better service?
Cheers
Posted: Wed Oct 19, 2005 12:05 am
by Cam
You can get a copper 'competition' type head gasket from most mini specialists (they also use the 1098 engine). I always torque the head first, then run up to working temperature then torque the head again when cooled down. Then re-torque again after 500 miles (first oil change).
Although if everything is OK a standard head gasket should not blow! Are you sure the head and block faces are true?
Posted: Wed Oct 19, 2005 10:32 pm
by bmcecosse
Not much in the way of competition gaskets for 998 engine these days - it's all for the 1275. But he says 'copper' gasket anyway. Maybe just bad luck - or maybe the head deck is now too thin and has warped or cracked - but at 70 thou it should have been ok. Only way to find out is to strip it and see what's up. My car blew the gasket 6 years ago - I had to change it at the side of the road with just ring spanners (walked a mile to get gasket from Autoparts and mile back again - and ever since carry a spare with me) and that gasket is still fine after 12000 miles of hard driving. So don't give up on it yet !
Posted: Thu Oct 20, 2005 7:04 am
by Alec
Hello Millerman,
if the head has recently been skimmed, then it should not be bowed, so I would suspect a crack in the head.
Alec
Posted: Thu Oct 20, 2005 5:58 pm
by millerman
Thanks for comments.
Head has been put back with a new gasket. I will torque down again tomorrow and I haven't given up on it yet . Alec, there didn't appear to be a crack, althou' job was done before I read your post.
I'll keep you informed if there are any more problems.
Posted: Thu Oct 20, 2005 6:01 pm
by Alec
Hello Millerman,
fingers crossed, but cracks can be quite indistinct and sometimes need careful scrutiny to detect.
Alec
Posted: Thu Oct 20, 2005 8:36 pm
by bmcecosse
Did you run the car any distance with the blown gasket ? And did you try a straight edge across the block and/or the head ?
Posted: Thu Oct 20, 2005 10:15 pm
by millerman
I did check the head with a straight edge and that seemed ok. ran car approx 1/2 mile with a blown gasket and I haven't checked top of block. Fingers crossed at present!
Cheers
Posted: Fri Oct 21, 2005 9:53 pm
by bmcecosse
Should be ok - think positive !
Posted: Sat Oct 22, 2005 6:24 am
by Peetee
but cracks can be quite indistinct and sometimes need careful scrutiny to detect
Yes indeedy. I spent hours in my shed last winter porting and flowing a head only to find the thing was cracked in two places. Without the clean up they wouldn't have been visible and probably not been a problem!
Posted: Sat Oct 22, 2005 9:59 pm
by bmcecosse
Which is why the 12g940 head is such a good idea. Dead cheap on ebay - and comes ready ported and flowed all you could really want for 948/1098 engine. Of course if it's a 1275 engine it can be further improved - but it's fine just as it is for the smaller engines.