urgent help needed, overheating badly

[justin3779]

update guys, ive got the blue cap and it seals fine. the car will run fine for about 10 miles then the water temp goes through the roof and so does the oil temp to the point were by the time ive gone from birmingham to coventry ive used 5 litres of coolant. i started it up today and the bottom hose of the rad gets hot almost intsantly so am i guessin its the thermostat ?

[Deano2711]

Does the bottom hose feel like it's full of hot water or hot air ??

[Ben Lessani]

If you've used coolant, then there's a leak, the head gasket has gone or the oil cooler has gone.

Sniff test the coolant, compression test the cylinders, investigate the oil.

5l of lost coolant, it should be very obvious.

Oh, and never drive without the expansion tank cap on.

[Deano2711]

If you've used coolant, then there's a leak, the head gasket has gone or the oil cooler has gone.

Sniff test the coolant, compression test the cylinders, investigate the oil.

5l of lost coolant, it should be very obvious.

Oh, and never drive without the expansion tank cap on.

Why not Mate....I was told by a garage that if the pressure is building up and you remove the cap the pressure is relieved enough to drive a short journey rather than sit at the side of the road. 

But agreed 5l of coolant is a lot and a leak would be obvious. Is the water coming out when you switch off the engine ??

[justin3779]

no wter is coming out anywhere, iv checked the cylinders and no coolant so its not the head gasket. im just totally confused

[justin3779]

its losing so much water cos its heating it up to the point where its blasting out as steam

[Deano2711]

Mine was similar when I first bought it. One of the to hoses developed a minute pin hole and I got an air lock in the system. Flushed out the coolant system and all has been well since. Follow the link pasted up on Page 1 of this thread to try to get rid of any airlock. This is the reason I said take the reservoir cap off as this would release the pressure and if the car drove ok for a short distance you would know it is an airlock and could set about sorting it out. Also did the bottom hose feel like it was full of hot water or hot air as this would explain the thermostat working or not.

[Ben Lessani]

If you've used coolant, then there's a leak, the head gasket has gone or the oil cooler has gone.

Sniff test the coolant, compression test the cylinders, investigate the oil.

5l of lost coolant, it should be very obvious.

Oh, and never drive without the expansion tank cap on.

Why not Mate....I was told by a garage that if the pressure is building up and you remove the cap the pressure is relieved enough to drive a short journey rather than sit at the side of the road. 

But agreed 5l of coolant is a lot and a leak would be obvious. Is the water coming out when you switch off the engine ??

Your cap is responsible for releasing pressure. The system needs to maintain a pressure of about 15 psi so that it can prevent the water from boiling. If it boils, it develops air locks and causes much larger problems.

If 5l is being blown out as steam, then you must be able to see where it is coming from?

[Deano2711]

I once took a 4x4 into the garage for overheating problems and was told the head gasket was shot and quoted £1200. Removed the cap and drove home 12 miles with no further overheating problems. Then changed the cap for a new one which cost £3.99 and the problem was gone. Sometimes it can help to remove the cap to release the pressure. I obviously would not reccommend driving for long periods without the cap but either as a test or a quick fix to get you home it can and does work as this event proved for me.

[Ben Lessani]

I once took a 4x4 into the garage for overheating problems and was told the head gasket was shot and quoted £1200. Removed the cap and drove home 12 miles with no further overheating problems. Then changed the cap for a new one which cost £3.99 and the problem was gone. Sometimes it can help to remove the cap to release the pressure. I obviously would not reccommend driving for long periods without the cap but either as a test or a quick fix to get you home it can and does work as this event proved for me.

I can't see what is it gain by doing it as a test?

On a car that is working fine, running it without a cap will cause the water to boil over, develop an air lock and leak coolant.

On a car that has an airlock, running it without a cap will help remove the airlock, but will then subsequently boil over, develop another air lock and leak coolant.

The only time the cap should be off the car is when it is stationary, I can't advise driving round without it on.