I am trouble shooting a leak that appears to be near the rear of the cylinder head on the exhaust side. The leak was probably going for a while, but in the past couple of weeks has rather suddenly become significant, losing about a pint in a couple of weeks.

It doesn't seem to drip significantly while stopped, but I see evidence of leakage on the top of the sump area of the oil pan section, so I think the leakage is happening while driving, or during heating/cooling cycles of operation.

Since it's hard to see back there with the engine assembled, I took off the exhaust manifold heat shield; the exhaust manifolds, the preheater box, etc. It looked dirty on the side of the block back there, so I cleaned all that stuff off and tried to determine where the leak might be.

The heater hoses at the rear of the head do not appear to be leaking near the fittings. I have recently replaced the ECU temp sender unit at the back of the head. I checked to make sure that it was tight, and it was. I see no evidence of a crack anywhere that I can see. Given all this, I'm now thinking that the leak might be coming from a head gasket leak near a coolant passage right at the edge of the cylinder head/block interface at the side of cylinder #5.

I have the Volvo B6304 engine manual, and from the pictures, it looks like there are coolant passages right near the edge of the head along side cylinders #5 & #6 which have communication with the lower head section. My best estimation right now is that the leak may be from the head gasket at one of these passages.

There is no emulsifiaction in the oil, and oil consumption is very low; less than 1 qt per 3000 miles. The car has 152k miles and is a 94 965.

Has anyone had some experience with a leak of this type? The car does not bear any evidence of overheating.