Bubbles in coolant, possible head gasket problem

[M25VAN]

I'm getting tiny bubbles appearing in the coolant when the stat opens. Is there any other possible cause for this other than the head gasket failing? Wanted to check before I replace it as it was only done about a thousand miles ago when I replaced a broken valve.
Just to confirm, head nuts were retorqued to 40lb/ft after a heat cycle and compression readings have not changed since replacement, 170psi on all four cylinders when hot. Used a Copper gasket that went on dry.
Any ideas?

[philthehill]

Before you do any stripping it may be worth a try at going through another heat cycle and re-torqueing to 45lb ft. You have got nothing to loose and everything to gain.

[M25VAN]

Will do, thanks and fingers crossed.....

[bmcecosse]

My advice is always 44 ft lbf and retorque after first heat cycle, and to wipe the gasket with a smear of grease before fitting..... But I very much doubt the bubbles are head gasket related..

[kennatt]

if you have that comp on all cylinders Doubt that its a head gasket,there can be bubbling just as the water is pumped through the system,if when you rev it with the cap off, the water is NOT pushed out of the filler neck,then you have nothing to worry about.

[M25VAN]

My advice is always 44 ft lbf and retorque after first heat cycle, and to wipe the gasket with a smear of grease before fitting..... But I very much doubt the bubbles are head gasket related..

Did this but only to 40, forgot the grease but at least I managed to resist the gasket goo. It took me so long to clean off from the previous gasket replacement I decided to try without.

if you have that comp on all cylinders Doubt that its a head gasket,there can be bubbling just as the water is pumped through the system,if when you rev it with the cap off, the water is NOT pushed out of the filler neck,then you have nothing to worry about.

Well it's only very tiny bubbles and certainly nowhere near pushing the water out of the neck. Presumably if it's leaking then the rev up forces air into the cooling system with consequent rise in level?

So it's going to be a further retorque but to 44/45, recheck valve clearances and keep an eye on....
Thanks.

[rayofleamington]

Grease on the gasket isn't proven to help at all - some will swear by it, but others say it adds more risk of early failure.

I used it when young and impressionable, as it was recommended word of mouth. Since working in engineering and mixing with those who really know their stuff, I don't do it!

What you do is up to you - if it caused a significant high risk of failure, it would be more widely disregarded. Therefore I assume the risk must be fairly small.

[bmcecosse]

The wipe of grease was handed down to me by folks building very successful competition engines. It's served me well, and I intend to keep following the advice !