White smoke

I have a 2009 Vauxhall Astra 1.9 CDTI SRI 150 and when it starts from cold it blows white smoke out of the exhaust and sputters between 2000-3000rpm. I have also noticed steam coming from under the bonnet, but can’t see any problems with the cooling system. It seems to run a bit better when hot.

Also, when I bought it the engine was covered in oil. I’m wondering if the head gasket has gone, as when I blanked off the EGR valve and ran it for an hour there was coolant on the blanking plate when I removed it. Is there anything else that could be letting coolant into the inlet manifold, such as the gasket? Are there any tests I can do before I start stripping the engine?

Wayne Erwin

One common failure with the Astra cooling system is a cracked coolant header tank. This can cause a leak in the system, but would not give the white smoke you are experiencing. As you also have steam coming from under the bonnet, I would try removing the expansion tank cap and starting the engine. If you have a failed cylinderhead gasket, I would expect to see coolant pushed out from the system and blown out of the reservoir. If this happens with a cold engine, you almost certainly have a failed head gasket. Although coolant does go through the inlet manifold on your engine, I would expect you would see some signs if this was leaking.

There are two basic tests that can be done. The first is a coolant pressure test. If you have access to a pressure tester, pumping up the cooling system and checking for leaks would be the first move. If the pressure drops but no external leaks are apparent, then start up the engine. This may emit more white smoke than it usually does, due to the coolant being pushed into the bores. Be warned that if excessive coolant enters the bores, the engine may experience hydraulic lock and possible damage.

Another test would be to use an exhaust gas analyser and place it just above the coolant header tank with the engine running. If exhaust gases are leaking into the cooling system due to a failed head gasket, the gases will be picked up by the analyser. When using this method, be careful not to allow coolant to enter the analyser pipe.