KV6 – oil on coolant, need advice

[bl52krz]

Originally Posted by Andrey Atmashkin

Yesterday I've my car back.
Cost for work and spares was about £1700. There was some kind of loosing seating between block and head. Strange fialure but it has been fixed. Look like a factory fault or something.
BTW I've changed cam belts one year ago and the garages did their job bad. He had tighten pulley-timing belt drive too strong and camshafts cracked while removing the head
Here are the pics:
Camshaft http://dl.dropbox.com/u/2656877/MG/cam.jpg
Pulley also was damaged http://dl.dropbox.com/u/2656877/MG/zvezda.jpg

It was a goodluck to find the LAST camshaft from brakers in whole city. (Also no new part camshafts here!)
Seems that this failures caused a strange knoking sound which is now disappeared.

As a conclusion. HFG is really RARE failure on KV6. But could happen...

Cheers ))

sorry it cost you an arm and a leg to get it repaired.
must have been a bit of a bodger who did the work on your car before.
you should always stick to the correct torque for tightening things like that.

[Paradroid]

Edited my post as misunderstood the previous one.

Can anyone clear up whether this overtightening could cause the heads to warp which would cause the head gasket failure. When I say failure I mean failing to seal, the gasket itself could be ok.

Just wondering as my car's had the timing belts done and is showing signs of head gasket failure, it's unlikely to be the same thing but did make me wonder.

[gerry3]

Originally Posted by Paradroid

Edited my post as misunderstood the previous one.

Can anyone clear up whether this overtightening could cause the heads to warp which would cause the head gasket failure. When I say failure I mean failing to seal, the gasket itself could be ok..

The short answer is Yes.
Tightening bolts imposes a tensile stress which causes the bolt stretch.
Providing that the stress ( tightening the bolt ) applied is less than the yield point of the bolt then the bolt will maintain to apply pressure to the parts being held.
However if the applied stress is greater than the yield point ( elastic limit ) then the bolt will stretch but not return to its original length. The result being that the pressure holding the parts is now reduced, giving much the same results as if you do not tighten the bolt enough .
Any further application of stress, ( tightening the bolt further ) would result in it breaking.
In your case I would be tempted to remove all the old bolts, leave the head for a day, to let it relax and then refit it with new head gasket, new bolts, all at the correct setting and order. Remembering to pull each bolt down in small stages.
Do not use the old gasket because it will have been squashed and will not reseal.
Could I also add that some on the forum state that the heads should not be skimmed because they are face hardened when in fact they are made from an alloy which AGE hardens, so all of the head is of the same structure right though. But that is another subject which I think is too long to go into in this thread.

Hope this is of help, Gerry3

[Paradroid]

Originally Posted by gerry3

The short answer is Yes.
Tightening bolts imposes a tensile stress which causes the bolt stretch.
Providing that the stress ( tightening the bolt ) applied is less than the yield point of the bolt then the bolt will maintain to apply pressure to the parts being held.
However if the applied stress is greater than the yield point ( elastic limit ) then the bolt will stretch but not return to its original length. The result being that the pressure holding the parts is now reduced, giving much the same results as if you do not tighten the bolt enough .
Any further application of stress, ( tightening the bolt further ) would result in it breaking.
In your case I would be tempted to remove all the old bolts, leave the head for a day, to let it relax and then refit it with new head gasket, new bolts, all at the correct setting and order. Remembering to pull each bolt down in small stages.
Do not use the old gasket because it will have been squashed and will not reseal.
Could I also add that some on the forum state that the heads should not be skimmed because they are face hardened when in fact they are made from an alloy which AGE hardens, so all of the head is of the same structure right though. But that is another subject which I think is too long to go into in this thread.

Hope this is of help, Gerry3

Hmm thanks. Well I'll mention it to my mechanic as a possibility.


I've still got the same problem though which is that it's very expensive to get the heads off the KV6 and until I do, I don't know what the situation is!