Cooling system staying pressurised

[natesterrano]

Hey guys, just wondering if there is any other reason apart from a head gasket being blown for the cooling system to still be under pressure ( not a lot, but still under pressure ) in the morning? Also, it is losing a bit of water out the overflow bottle each day. Ive tried two different radiator caps and I replaced the thermostat 6months ago. grrr. Just seems strange being such a solid engine, cast iron head+block

Ive got one of those tee-kay head testers for exhaust in coolant, but its at my brothers' down in Bombay at the moment. I might give that a try next week.

[zukmeista]

Got any white stuff under the oil cap or in the radiator? Could be leaking somewhere as well, you could pressure test it and see if it leaks anywhere.

[slide]

When you say loosing from overflow bottle, thats dropping away from 'max' line ? If you filling it to top, yes it will always drop.
Very odd to have pressure still. How do you know that tho? I just can't think of any reason that it would have any. Unless radiator cap rated too high, so builds lots of pressure then contraction of everything is less and has absolutely no leaks anywhere...

[natesterrano]

No i mean, after correctly filling the radiator and overflow bottle a couple of days later the overflow bottle is fill to the brim and coolant is being dumped out the overfill tube on the overflow bottle. Also when cold the system is always still a bit pressurised? Ive tried two different radiator caps, both .9 bar/13 psi. Will see what the one I put on today does tomorow morning.

Oh no oil in the water/ water in oil

cheers

[pressy]

is it pressure or vac ?

[natesterrano]

Pressurised. Hoses are pressurised before release of pressure by removing radiator cap. Im gonna take it to the radiator shop today, see if they can pressurise it and see if it drops pressure.

[natesterrano]

Pretty sure its blown headgasket, took it in to a radiator repair store to see if they could do a coolant pressure test. They just looked at it and said "thats far too much pressure to be in the cooling system, you should get a leak down test done" ( didnt even take the radiator cap off). Im gonna do a teekay head check tomorow instead. Im 99% certain its gone, or a crack in the head or something.. but it seem strange these engines are supposed to be bulletproof! grrr

[Dirtydog]

any engine can blow a head gasket, doesnt matter how bulletproof they are.

cracked head is a different story though.

let us know how you get on as im interested to see what the cause is, learning and all that jazz

[The Stranger]

Hard case, one would think if the head was cracked or the head gasket was leaking then the pressure would have gone back out of the cooling system overnight via the leak/crack.
I guess it could be watertight at low temps but opening up at high temps.

[Crash bandicoot]

Is said engine turbo charged....?

If so does said engine have water cooled turbo charger.

If so how many kms or how old is the engine in question. .

the possibility being that the turbo charger could be forcing compressed air past seals into the gallery in turbo housing....

Shaft seals are designed to keep fluid in. doesn't mean they keep other things out in effect its a one way system so may keep the pressure trapped and not leak back.

food for thought.

[slide]

food for thought.

Indeed. I had never thought of this. Usually the boost pressure wouldn't exceed radiator cap pressure, but on a boost-upped engine, yea, could be.

thats far too much pressure to be in the cooling system

Too much pressure can only be caused by radiator cap or overflow pipe/tank blockage. Else cap will vent pressure, maintaining a peak of 13psi (or rated cap pressure).
How quick it builds on the other hand...
If pressure builds real quick, then yea, somethings amiss.
Try look for bubbling in system (cap off, level full, engine running).
Or, a sure sign things are bad, if theres bubbles in overflow tank coming from the overflow pipe with cap on, engine hot and idling.
Bubbling coolant is not always from blown gasket/head, hence teekay test usage. But if theres no bubbles, teekay test no use to ya.
Might be bulletproof, but that doesn't mean it can't be destroyed with a sword...
Nath