Smoking after ticking over for a while

Dave c wrote: hissing radiators in the morning hmmmmmmmmmmmm new one on me.

Thats what i thought and i have been in the motor trade 15 years !

Don't believe me then

I guarantee my jimny doesn't keep the radiator pressurised with gas in the top when cold.

It is supposed to be full up to the top with water. When the coolant heats up it expands and increases the pressure, (which raises the boiling point). if it goes above the cap pressure the rubber seal comes off the seat and lets the extra coolant into the expansion bottle. Now when it cools and contracts it should go below atmospheric pressure and get fluid pushed back from the bottle via the one way valve in the centre of the cap. (Or the hoses will go all flat)

With a weepy head gasket cylinder pressure will leak into the water jacket and blow extra coolant into the expansion bottle, and when the coolant cools down and contracts there is a space in the top of the radiator filled with air under slight pressure.

You can do a test from the radiator cap with one of those hand pump testers until you burst a hose and you won't get water to go into the cylinders unless the gasket is so gone that a compression test will show you the problem.

A leakdown test is better, (with the crank blocked at TDC you pressurise the cylinders one at a time to about 150psi and look for bubbles at the radiator cap, or measure the pressure drop over a set time, : -but this could also be rings or valves), and the hydrocarbon test of the water is another good test, but these tests involve time and money.

With a cold engine water hoses hard and hiss from rad cap on opening means head gasket weeping.

247sniper wrote:

Dave c wrote: hissing radiators in the morning hmmmmmmmmmmmm new one on me.

Thats what i thought and i have been in the motor trade 15 years !

same as mate iv never come across that before but i will undo my cap in the morning before work but well we will see

In the OPs case, I still don't think it is actually steam from a head gasket leak, possibly it is oil smoke from oil leaking past the valve seals, or something wrong with the breather system. (Does it use oil?)

There is also a slight possibility it is brake fluid from a faulty servo, but you would notice the fluid level dropping significantly.

hi thanks for all yor help
I think there is something in all what you have said but the coolant was down this morning NO HISSING though so filled up with coolant cheeked oil. I drove to work not having to stay on tick over anywhere. No smoke screen.when car had cooled down I opened radiator cap and there was space in the top there are no leaks in hoses so something like facade says has happened. but no pressure in the system on opening cap.
How do I check breather system as this also sounds about right .Ive got a disc with manual on it but find it alot more difficult to use than a heinze manual
Cheers Tom
when there is smoke I mean ahuge amount like you could hide in.

What colour is the smoke?

If it's blue you are burning oil, if it's white it's water.

How can we account for the coolant loss though if there is no leak. Still sounds like headgasket to me.

If the smoke is blue though it could be valve stem seals.

If it were the head gasket and you were burning that much water, I'd expect to see the mayonnaise in the oil by now though.

Can you see the rainbow of oil in the coolant when you take the rad cap off or in the expansion tank?

You could always get a compression test done to see what that tells us.

It's alright all us suggesting stuff but it's so much easier if you have the car. I could give you a relatively definitive answer in about half hour if I had the car here at my workshop!

Perhaps get it to a good local garage for a proper diagnosis.

Kirkynut