Diesel Smoking ( white/grey)

[vauxsqueeks]

Hi. Would like to know your thoughts..

I have been asked to look at an Astra G ( 54 plate 1.7DTH ) It does smoke ( white/grey quite a bit) when cold but does clear up when warm. It is loosing water and cant see any leaks. I have put my hand over the exhaust and it does not appear to be wet/damp but the water loss is too much for a small leak.

Any ideas on where to look? could this be a head gasket? as I dont know much about diesels.

I am assuming that white/grey smoke would be water and possibly head gasket or similar.

Thanks.

[Retro Pedro]

If it's definately losing coolant then I would have thought head/head gasket related. Have you tried a leak test via the expansion tank John?
http://www.ebay.co.uk/sch/i.html?_sacat ... +leak+test
Believe on a diesel when combustion gases are present, the raw state blue fluid turns yellow and on a petrol it's green.

[vauxsqueeks]

Thanks for the link Ill pick one up. Was wondering about how it worked.

When the expansion tank cap is unscrewed, loads of pressure is released and it does have a sort of FOG/smokey mist to it!

Was kind of hoping it wasn't going go be a head gasket. its odd that there is no dampness from the exhaust.

[Rifleman]

Yep Its deffo the head gasket mate.

[Retro Pedro]

Does the raditor top hose go hard? Believe that's another indicator that the coolant system is pressurising.

Not sure if an air lock in the system would cause the problem - thinking that if the coolant system is constantly being topped out there would be a greater chance of air locks in the system. But to me honest, that might be just wishful thinking on my part.

I can relate to this because I've been running my Kia Sedona diesel with initial similar symptoms at least for the last 4 years. In my case, the coolant system used to pressurise back through the expansion bottle and used to boiler and pressurise and even scalded the under side of the bonnet. Oil stayed as clean as a whistle with no evidence of mayonnaise. Touch would, still does.
In my case, the branched off rear heater feed and return hoses had corroded without me realising. On the Sedona, there is a metal pipe section that runs over the top of the exhaust system, and it was these pipes that had corroded. After sorting out the leaking pipes, the pressuring through the header tank stopped, but to this day, it still loses 2 litres of coolant (capacity 9.5 litres) approx. every 300 miles. Weird thing is, to this day, the engine still pulls like a train.
The coolant temperature gauge gives me the warning sign when a coolant top up is necessary. It normally reads between a 1/4 and 1/2 on the gauge, but when the coolant top up is required, it will gradually rise to the red full mark but will fluctuate down towards the 1/2 mark. I always thought it was the thermostat opening fully to allow the coolant to cool but since have understood that the thermostat is open all the time. So it must be the radiator fan doing it's job.
When I top up the coolant, I back fill mine to try and avoid getting air locks as much as possible. My thinking is that if coolant goes back down through the engine, up through the raditor, with the radiator cap off, any air will be allowed to escape rather than be trapped behind the closed thermostat.
I still get white smoke after top up but after a couple of days it stops smoking and runs clean as. All very weird but I'm not complaining.

[Rifleman]

Its got nothing to do with air locks mate. Also the cooling system is alwaya pressurised, thats how it works.
The reason it is loosing coolant is because the head gasket has blown across the water jacket and the cylinder.
The coolant goes into the combustion chamber and this causes the white smoke.
Whatever you decide checking, you will only cure the problem by replacing the gasket.

[Retro Pedro]

[Rifleman]

Depends on the engine type bud. Aluminium heads tend to damage much easier that steel ones.
Usually with steel ones you just clean them up and refit with a new gasket.
Unless the engine has been really cooked and has warped the head.

Aluminium heads should always be checked for cracks etc and skimmed before a rebuild.
Porous heads are very rarely heard of.

[vauxsqueeks]