OT - Astra Ecotech

A close check of the water pump area might help. Sometimes the pump only leaks when stopped in a certain position. It had me going for a while. If in doubt you could try using the Vauxhall product called Stop Leak or something like that. In the trade it is known as a dog turd 'cos that is what it looks like. Alan

I had this problem on a RR with the VM enigine. It had a water gallery that bolted on the top of the cylinder heads (four individual ones) and it had somehow become deformed. I only noticed it when hearing the "hiss" as a drip hit something hot. Otherwise I'd have not found it.

Another method of testing if the hiss test fails is to get one of those mirrors on a telescopic stick. Get it cool in the fridge then quickly have a poke around the hoses when hot but not running. If there is steam venting the mirror will steam up. Other coolant tricks tend to be split hoses that only leak in a certain position such as under acceleration so a real goot poke around the hoses may help.

I'd also consider removal of each hose , inspection and refit with some suitable sealer but that would be my next to last course of action. Last being the compresssion test.

If the head had gone big time he / she would know it as it would be like driving a boiling kettle down the road as far as emmisions are concerned. Had that on a Rover 220 at work a few years back and it was fully apparent.

Only other thing I'd be looking for is the cabin steaming up which may indicate a duff matrix in the heater / weaping hose. I don't know if your inspection included this so won't be offended if you've already tried this as I suspect you may have.

Lee D

Sounds like it's got to be a split in a hose that you can't see or which only shows itself under certain conditions or under load, say when accelerating hard maybe. Might be worth getting the engine warm/hot, and kneading the coolant/heater/ pipes (with a pair of gloves on) and seeing if you can spot water escaping. I'd also try it with someone sat in the car, revving it to 3k or so whilst checking the hoses. Bit tricky, so be careful ... ;)

Doesn't this mota 'ave anti-freeze in it? That normaly leaves behind a tell tale pink, blue or green stain in the area of leaks...

...and you can frequently determine roughly where the leak is by smell.

What happens with the coolant hot and the coolant reservoir cap off?

Head blowing into the coolant can be detected by CO2 concentration in coolant.

AJH

In message , Mark Solesbury writes

Any non-franchised air conditioning specialist can put a UV dye into the coolant and then use a UV lamp to find the leak. It's what they do with AC units, I don't see why it can't be done with the coolant system.