c20ne blown head gasket help????

[mart25]

can anyone tell me what the symptoms are for a blown head gasket please.

my coolant header tank is pressurising after only a few moments of the engine being fired up but temp reading on dash says all is normal , am i right by thinking this is either a broken head gasket or a cracked head maybe. when i say pressurising i mean when i take the header tank cap off there is lots of pressure then the water just shoots out of the tank like a volcano... any help would be appriciated.. thanks. p.s im pretty sure the water pump is working fine and circulating round the system fine too...:confused: :confused: :confused:

[Mattig Nic]

Obvious symptoms include:
-a creamy 'mayonaise-like' residue built up inside the header tank OR check under the oil cap. (You may find a little thin whitish colour resdue under the oil cap. Don't worry if you do - this will most likely be caused from a little condensation, hot engine parked on a cold night perhaps) Only worry if its very thick (just like mayonaise!)...

-white smoke from exhaust. This is basically steam exiting the engine due to the water being burnt from within.

-Misfires....

-If you leave the car parked up, say overnight, the coolant may leak inside the cylinder(s) and effectively lock the engine up (liquids can't be compressed). [CHECK COOLANT BEFORE YOU TURN ENGINE ON EVERY TIME]

This will be obvious in bad cases as when you turn the ignition over, the engine will just 'clunk' as the starter can't turn the crank.
It may be able to turn the engine over after a couple of attempts if it shows this particular effect, but i wouldn't reccommend because if your really unlucky, you could end up bending a rod....(theoretically, it's possible..)

If you think one or more of your cylinders have filled with coolant, remove the spark plugs. It will be obvious which cylinder is 'open' due to the condition of the plug(s).

With the spark plugs removed, turn the engine over. If any coolant is trapped in the cylinders, it will eject, with some force!, out from the spark plug recess. If you want to keep things clean, get a pal to hold a rag over the suspect cylinder...........then!! Get the plugs back in, fill the header back up and drive slowly to the nearest place that you intend to fix it!!
It is possible to drive the car without any coolant, but stop often and dont drive far!! [I DO NOT ADVISE THIS PERSONALLY AND DO NOT ACCEPT RESPONSIBILITY IF YOU MIS-JUDGE YOURSELF AND END UP COOKING THE ENGINE!!]

Hope that helps, essay!! Nic

[mart25]

yes that does help thanks. but dont have any of the above symptoms just lots of pressure in the coolant system like say enough to blow a hole in my radiator :-( any other ideas please... thanks

[Sloth]

air lock or blocked rad, personally the former tbh.

[brainsnova]

take the cap of and let it run squeezing the rad hose.

[mart25]

take the cap of and let it run squeezing the rad hose.
yeah cheers done that but as soon as i put cap back on and undo again lots of pressure and bubbles over like a volcano erupting again..???

[brainsnova]

is the thermostat operating.

[mart25]

the temp seems fine/normal on dash yeah . hav'nt checked thermostat manually tho?

[spanna]

now i had this problem with my sr with the rad cap on run the engine up and try to squeeze either top or bottom rad hose if you cannot squeeze them you will most probabilly find that you have a headgasket blow betten the fireing ring and a water way. another way of checking for this it to take off rad cap wen cold and smell the water.if it has gone between the fireing ring and water way you will get a smell of petrol in your expansion tank