940 Head Gasket issues?
 

I think my head gasket has been suspect for some years. Although there is no oil and water mixing, every winter I can often see clouds of white smoke/steam? from the exhaust even when the engine is hot, not just when warming up, although not all the time, it is intermittent and every Sunday I have to top up both oil and water ready for the week's commute ahead, it's been like this for years. I've read of the different ways the head gasket can fail. Also she has clearly lost a lot of horses in the 9 years I've owned her. Its stayed stable for years though.

Recently I think the issue has worsened. There is a leakage of water where the block and the head join and although it looks very minor I imagine that when driving and under pressure a lot of coolant is being lost and for the last few Sundays, after a week's driving of between 150 - 250 miles per week I will have to fill up the entire header tank. I assume this must be head gasket? I've been very gentle with her on the motorways the last few weeks, no high speeds and keeping an eye on the coolant all the time.

My garage labour rate is very fair and they do a great job. How many hours work is head gasket replacement on average I am wondering?

Is the leakage of water where the block and head join at the front Ellie? If so it is likely to be the rubber seal between the water pump and the head. A tiny leak will leave deposits of antifreeze and/or limescale which will crystallize and then grow, expanding the leak.

I'm guessing you use normal unleaded in the petrol tank? As you know, when you first start the car, it runs of petrol for a short time until switching to LPG, depending on engine temperature etc.

Normal unleaded now has 10% ethanol which has a higher water content than the old normal unleaded had. Might not sound much but could well be enough to cause the steam you describe, especially if the steam disappears when running on gas.

You could also have an oil leak somewhere or other and the PCV system may be blocked which would cause more oil leakage. Might be worth having a compression test done just to be on the safe side but usually a head gasket change is about 3-4 hours. The timing belt has to come off so bargain for one of those as well if you go down that route but that isn't a bad thing.

The leak is at the side, not the front. Water pump and seal were renewed not that long ago.

The exhaust white smoke/steam can occur hours into a journey, whilst I've been running on lpg for ages, it's not just at the start of a journey.

3.5 hours for a head gasket change ,( 4.5 for the turbo model ) but be prepared for some alloy head corrosion if coolant has been neglected which may or may not need attention ...

3.5 hours for a head gasket change ,( 4.5 for the turbo model ) but be prepared for some alloy head corrosion if coolant has been neglected which may or may not need attention ...

LPG and white smoke
 

It is quite normal to see white smoke when running on LPG due to the burning process of LPG compared to petrol. Due to the LPG consist, the LPG process relies much more on burning hydrogen to water than carbon to CO2, like petrol. This one of the main reasons LPG is cleaner than petrol. The exhaust gasses simply contain more water. Especially on colder days you will see more white smoke coming from LPG car than petrol/diesel cars.

In general, loss of coolant is more often due to a (hidden) leak than a failing HG. Do you fill to the MAX mark? In that case the remaining system volume often seems to be too small and many 940s will simply cough out coolant via the filler cap until the MIN mark is reached again. Top up when cold just over the MIN mark.
Especially since your coolant level is not stable I would recommend to replace your expansion tank for a tank with a minimum level switch. On my 940 I sacrificed the washer fluid low level indicator wiring for easy installation.

If your LPG system has an evaporator, this could also have an internal coolant leak.

If you have been adding fresh coolant every week, it will be sufficiently recycled by now.

Seeing as it is leaking at the side you will need to do the head gasket regardless.

Labour time will be 4-5 hours on a Turbo car. The head might need welding. Make sure they have the head resurfaced regardless of how flat it might look.

I would also get them to check on bore wear with your oil consumption issues

I have experienced similar symptoms, suspected head gasket failure but found the cause to be far more mundane.

Thanks to Laird Scooby for clarifying that these experimental mixtures the greenwash brigade would have us believe are petrol contribute to excessive winter exhaust vapour. I always use super-unleaded which is supposed to be capped at 5% ethanol. I expect it still contributes to this effect though.

In my case there were multiple culprits for slow coolant loss and a soggy engine bay.

• Suspect expansion cap
• Leaking small hose between the top of the radiator and the expansion tank
• Cracked radiator side plastic tank - only leaked when hot
• Newish oil cooler hoses needed the jubilee clips tightening

I fixed all these myself relatively cheaply. A new Nissens radiator was only about £100 from Eurocarparts using the right coupon code.

Don't forget the head will need skimming so it won't be done the same day.

Plus of it is anything like the 531 head I've just fitted to my 940 when you take the exhaust manifold off studs will snap or pull out of the head so they will need drilling and helicoiling.

Cheers guys for all this information. I will let you know what happens, it won't be in the garage until after I come back from holiday.