UK Car Repair/overheating
QUESTION: ive a omega 2.2 petrol it started to overheat after a cold spell we had so ive changed thermostat and it still overheating it seems that when i drive the temp goes up soon as its hot then when i drive it starts going down if i release the tank cap it is bubbleing like mad when i stop at lites it goes back up to red again heaters blowing cold if iam sat at lites i have to keep revs tp 2000 revs to get it to go down
ANSWER: if theres no loss of water, no mixing of oil and coolant (white/creamy sludge on oil dipstick) then it's the waterpump.
check the waterpump belt is tight and the pump is turning first. if it is turning at tick-over then its a bad pump.
air bubbles in expansion tank/radiator usually indicate 'cylinder to water-jacket' headgasket leak though (cylinder gasses leaking into water jacket)... if you're using pure water without coolant then it might be ok (water boils at lower temp than coolant, the bubbles may just be steam).
a compression test will prove one way or another if there is a leak.
Do not use pure water for coolant- 3 to 1 (3 parts water to one part coolant - or stronger, no more than 75% coolant though)
best to be precise ;)
replace waterpump, put in proper coolant, get compression test(fingers crossed), enjoy.
---------- FOLLOW-UP ----------
QUESTION: sorry what i ment by bubbles is its boling hot when i got the car i dont think it had any anti freeze in it now ive put it in since doin new thermostat its overheating more than ever if gaskit has gone is steel seal any good to use
if its boiled dry previously the gasket is toast.
sealant liquids are a good way to turn a bottle of coolant and gallon of oil into sludge, they never work!
the head needs to be taken off the engine, checked for distortion and skimmed. Then refitted with a new gasket. any short cuts are foolish, we're talking 600psi of pressure held in by 2 faces of metal... liquid gunk is not going to work - plus, it tends to block the radiator, jam the thermostat, ruin the catalytic convertor, jam the piston rings and fall into the oil and wear down the crankshaft bearings.... yay!
Skim the head and refit with new gasket.
or, buy a 'known good' head(and gasket set, known as the head set) off ebay - probably a lot cheaper.
A fair garage will fit the head for £150 $230 approx
for them to do the whole job double it. a head (a 2.2 vauxhall head from same year - almost all the same)and gasket set should cost £85 $140 + £130 $200 for fitting.
Not too expensive if you're clever about it.
If you wish, I'll hunt the parts and an honest garage if you give me your approximate location (town/zipcode)
If its NOT boiled dry and oil is Not mixing with water just change the waterpump.. if you can get the temperature to stay normal by running at 2k revs then its classic 'naff waterpump' (pump has lost efficiency and needs to spin twice as fast to pump sufficient water).
if it drives ok like this and temp stays at a reasonable level then its ok, just fit a waterpump.