Engine failure

My 2001 Suzuki Grand Vitara 2.0 broke down near my home. There was a strong smell of petrol, thick white smoke issued from the exhaust tailpipe, and the engine warning light came on. My code reader detected the code ‘P0303 – Misfire detected cylinder 3’.

I changed the plug and coil pack and fitted a different injector. I also took out the plug and connected it to the coil pack while sitting on top of the engine; I did get a weak spark. I have carried out a compression test, the results of which were: No 1 cyl – 150; No 2 cyl – 180; No 3 cyl – 240; No 4 Cyl – 150. I am assuming that the reason for number 3 cylinder being so high is because of unburnt petrol on top of the piston.

There is no oil in the water and no water in the oil; there are also no air bubbles in the radiator or header tank. I have carried out a continuity check on the cables to the injectors and all were OK. I haven’t done an Ohm test on any of the plug or injector leads.

My vehicle was towed to the local garage three weeks ago, they have checked it and are baffled. C Roberts

Given the symptoms, my first thought is that the head gasket has failed. Running through the symptoms of white smoke and the high compression on No 3 cylinder would suggest that water and not petrol was the culprit. Petrol in a vapour form would ignite in a hot exhaust. Whenever I have experienced a petrol vehicle overfuelling, the petrol washes the bore and lowers the compression. Only a thicker substance like water would raise the compression.

This could be checked by removing the fuel pump fuse and disconnecting the coil packs, then spinning over the engine with the spark plugs removed. This should clear the bores of any excess liquids. The compression test should then be repeated, knowing that fuel was not being injected into the bore.

Crossover of fluids from the oilways to waterways does not always occur as a result of a head gasket failure. This failure may also be attributed to a crack in the cylinderhead, which may have occurred in one of the valve ports. The thick white smoke could be caused by burning oil, but this would have a far more pungent smell and the spark plug would also more than likely be contaminated with the oil.

I suspect that the head gasket needs to be removed and checked. To confirm this further, a cylinder leakage check could be carried out. This can be done with a compressed air system to pump air into the cylinder; the equipment is not expensive although a compressed air system is required. This will give a better picture of what is occurring within the cylinder.