Expansion tank and white smoke,

[parker13]

Hello, hoping for some help, I originally posted here https://www.volvoforums.org.uk/showt...v70r+expansion concerning the cap on the expansion activating at normal temp, all been well for months but tonight the valve on the new cap opend, Lost about two litres of fluid, happend just before I got home so soon as I got home boiled a kettle and went to top up the coolant, whilst doing this noticed huge volumes of white smoke coming out the exhaust, reved it to clear the system but still the same, no sign of water on the engine oil cap or dipstick, I've tied a bag over the oil filler and it inflates indicating a pcv block but could this cause extra pressure in the coolant system?, I really love this car but don't have the money for expensive repairs,

[Kev0607]

Is the temperature reading on the dash normal?

Do you ever have to top up the coolant?

PCV is a separate issue, so I don't think that's related.

Is it actually white smoke from the exhaust or steam? Smoke will linger, steam will disappear fairly quickly when it mixes with the outside air.

When the engine is cold, start it up & remove the expansion cap & see if there's any bubbles in the tank. That would indicate a head gasket issue.

[RollingThunder]

I'm afraid it sounds like a head gasket to me You can buy a test kit to verify that exhaust gases are in the coolant. That would be my first option as you won't always get emulsified residue on the dipstick.

As a general rule -

white smoke = water
blue smoke = oil
black smoke = over fuelling

[280E]

Either a head gasket - or a new Pope has been elected

[parker13]

No bubbles in the tank from cold although problem only occurs when the engine is warmed up, temperature gauge is spot on, seems to be steam from the exhaust,

[Kev0607]

Originally Posted by parker13

No bubbles in the tank from cold although problem only occurs when the engine is warmed up, temperature gauge is spot on, seems to be steam from the exhaust,

Have a look at this video;

+ YouTube Video

As mentioned by RollingThunder, you can buy a test kit to verify if there's exhaust gases in the expansion tank, which would indicate a head gasket issue.

[cheshired5]

Just smell inside the expansion tank. It should smell of nothing much as it's a sealed system containing only coolant.
If there are exhaust gasses constantly being pumped into the cooling system via a breach in a gasket, you'll smell the gasses.
No chemicals required.

[parker13]

can anyone recommend a tester for the coolant?,

[Kev0607]

Originally Posted by parker13

can anyone recommend a tester for the coolant?,

Try your local motor parts shop. Although, you don’t actually need a test kit. Just smell the coolant & check the colour. It’ll be obvious if there’s an issue with the head gasket.

[acshortt5]

Another outside possibility is a faulty oil cooler allowing oil and coolant to mix. The oil cooler will be either in the side of the radiator on an early car or post 1998/99 it will be on the rear of the sump.
Any oil film in the expansion tank?