Head / Block Leak (Possibly)

[John P]

This car is driving me mad.  Every time I think everything is sorted and go for a short run something new occurs.

This time there is a hissing sound from the engine which seems to be coming from the head / block joint area at the side of the engine just below the top water branch (High Compression Head).  When first started there are a few small bubbles along this joint line but I can't be certain if it's actually from the head / block joint or something related to the exhaust manifold joint.    The car doesn't seem to be loosing any cooling water.

After a few minutes it seems to stop visibly bubbling but still makes the hissing sound.

Curiously the noise isn't continuous, as I would have expected from a water leak, but related to the firing of the engine, rather like the hissing of a steam engine when it's running.

Having only managed to drive the car around 30 miles this year I'm very reluctant to strip it without any clear idea what's likely to be the issue.

The only thing I've done since it was last OK is remove and re-fit the spark plugs.  Previously I've only tightened them fairly lightly but having seen a recommendation of 30 ft lbs I did tighten them much more than in the past.

Any suggestions?

John.

[Chris KC]

Sounds like you have a leaking gasket, either the head gasket or exhaust. 
If it's running OK and not consuming water it can't be all that bad, but better attended to in case it gets worse.

There's no need to torque up spark plugs, finger tight + a quarter turn should be sufficient.

[Alan]

Get some soapy water and a paintbrush. Brush the water along the head/block spilt line and the spark plug holes. It will be obvious where the leak is.

[Austin in the Shed]

Get some soapy water and a paintbrush. Brush the water along the head/block spilt line and the spark plug holes. It will be obvious where the leak is.

Was going to say the same thing !