Pressure problem with cold radiator

[Pete]

Right then clever folk, let's see if we can work this one out together! Thankfully it's nothing to do with how I decided to get off my bike during an overtake the other day ( ) and is in fact to do with the car (for those of you that know about the cars I drive, yes it's the one that was pissing coolant out a few months back!). I can't drive it for longer than 10 minutes without the engine temperature shooting right up to nearly the red line. I've worked out that if I keep it in a high gear, drive at no more than 60mph and keep the warm blowers on all the time (and windows down!) the temperature stays OK (as long as I don't give it any juice...I'm talking keeping revs below 2,000rpm when pulling out of junctions!).

Whenever I turn the engine over it makes a weird bubbly noise, so my first thought was a problem with the radiator, perhaps a lot of air in the system. I let it cool over night the other day and in the morning took the radiator cap off and it shot out! Where could this pressure be coming from, could it be excess air?

I drove the car for about 15 minutes this morning and am waiting for it to properly cool for another hour or so before removing the cap and just letting it go for a piss. After that I'll top it up, run it for a minute or so, check level, top up, etc. etc.

Now, does anyone have any other ideas before I go ahead with this? It's very strange considering it's been running fine for the past couple of months and now all of a sudden this !

[Guest]

replace the coolant and bleed the system.

[Pete]

Well the coolant's fairly new, only a couple of months old so I could just bleed as is I guess. My other thought was that the thermostat could be bost, but would it still make a bubbling sound when it's fired up I wonder?

[archiec]

I would have said thermostat,take it out and place in boiling water to see if it opens

[Guest]

yep could be thermostat, but you'll need to drain the coolant and take it off..

[Pete]

Thanks chaps! Will have to be tonight now, I'll see what happens. Bloody cars, should get a new one really!

[tony-1977]

Hate to say this, but I'm 99% certain it's your head gasket. Driving at low revs with the heaters on will get rid of engine heat quicker (out the blowers in the car), but will not effect the thermostat opening or closing. The bubbling you hear when turning the engine over is pressure from the cylinders entering the cooling system, where there could be / is a leak in the head gasket. This will cause greater pressure in the cooling system (from compression in the engine), hence the temperature increase. Removing the thermostat will not have any effect on this, as the pressure increase will still be apparent. Hope this helps

EDIT: Just re-read your post.... Removing the rad cap in the morning (after standing all night) and coolant shooting out WILL BE head gasket failure. Sorry mate!!!

[Pete]

Hate to say this, but I'm 99% certain it's your head gasket. Driving at low revs with the heaters on will get rid of engine heat quicker (out the blowers in the car), but will not effect the thermostat opening or closing. The bubbling you hear when turning the engine over is pressure from the cylinders entering the cooling system, where there could be / is a leak in the head gasket. This will cause greater pressure in the cooling system (from compression in the engine), hence the temperature increase. Removing the thermostat will not have any effect on this, as the pressure increase will still be apparent. Hope this helps

EDIT: Just re-read your post.... Removing the rad cap in the morning (after standing all night) and coolant shooting out WILL BE head gasket failure. Sorry mate!!!

 

Hats off, a hand shake, pat on the head and a free beer to that man! Spot on Tony! No drama for me as it's my dad's car lol! He took it to the garage today and they've quoted.......£400 to fix it! Of course I had "no opinion on the matter", but for a car that's probably worth half that...well, need I say more!? New car time me thinks!

[tony-1977]