Coolant Loss And Air Locks

[sambulance]

hi all

for a few months now my car has started to lose coolant and today the car over heated when the mrs took the car on a long drive. went to rescue her and added some more coolant and drive 40 miles home with no problems. i am at a loss now as to where to start looking to repair the problem as i can find no leaks inside or out. i have no misting with the windows. the oil is clean with no coolant present but the car seems to have this problem on most long journeys now. most short journeys the car never get much above 80c, so i can understand its happening when the engine gets to full temprature. also the coolant always gushes with air when i open the header tank, but it has always done this since ive owned the car (4 years) and returned to the max line, untill now.

does this point towards head gasket failure or has anyone has had these symptoms?

also the car drive fine after the mrs boiled it. 

any advice would be great. thanks

[chromedome]

Years ago I had a similar problem on a different car. The car would drive every where with absolutely no problems. Go on a long run and it would overheat and of course force coolant out.

 

After a lot of investigation it turned out to be a hose that had gone very soft. Continuous flowing of hot water through it would make it pinch together and restrict the flow of coolant and overheat. Replaced hose and problem went away.

 

It may be worth having a feel around for a super soft hose.

 

Failing this you may need to get the system pressure tested.

 

Hope this helps.

[insanitybeard]

Could the thermostat be at fault? If it's not working properly it could be preventing proper coolant circulation around the cylinder head causing overheating in that area. Is it a petrol or diesel?

[chrispb123456]

I take it when you say you are removing the cap that the level has gone down? and as you remove the cap air and some coolant is lost as the level rises, (you can compress air but not a liquid).

 

All that air has to come from somewhere? answer compression pressure leaking across head gasket joint into the water jacket, worst case cracked head.

 

If your removing the head yourself you will almost certainly need the head refaced as 4 years of early stages of HGF has now taken it's toll

Edited February 11, 2014 by chrispb123456