I've been reading articles on your here for a few months and have found it a very helpful friendly site. I have a poorly 1999 3.0L Elite Estate.
I've been losing water for sometime which has got progressively worse. It is not the HSE valve as this was replaced, when I started losing water, this slowed the rate of loss down, but did not stop it. It is now misfiring on tickover, once the engine has warmed up, but is ok underload above 2000rpm. There is also no steam from the exhaust on a hot day when the engine is cold, only when it is up to temperature. The dis pack and plug leads were replaced about 15,000 miles ago, but there is oil in the plug holes (cam box gasket leak?). There is no oil in the water and there is no white gunge on the oil dipstick.
I have done the test suggested in one of your help articles by filling the radiator expansion tank to the top, left the cap off and there is air returning through the top tube on this when I rev the engine, it also smells of exhaust fumes!
Yesterday I did a compression test on a warm engine (I think is it the nearside bank of cylinders that is missing as the plugs were cooler than the offside, when I removed them). What is puzzling me a bit are the results, as I would expect the compression to be lower if a head gasket had gone, but for two of the cylinders, on the nearside bank, it was much higher. The only reason I can think for this is that water is being drawn into the cylinders and this means that there is less room for the air to compress and making the reading higher?
The results were:
drivers side:
back: 230psi
middle: 252psi
front: 238psi
nearside:
back: 297psi
middle: 265psi
front: 235psi
Any advice on whether you think head gasket has gone would be appreciated as I don't want to strip the engine down and replace them unnecessarly!