Nova overheating

[Traci66]

Son in law has a Nova on a K plate, he has just down a journey of approx 30 miles and noticed that the temp gauge was right up, this dropped slightly and then went up again, as he is wanting to take it to Santa Pod this weekend, any ideas would be most welcome. The engine in it is an X14XE tigra.

[tonyav]

Probably the thermostat is stuck closed or maybe an air lock in the cooling system. Has the car lost any coolant ?, check the oil make sure no coolant has got mixed with it ( sign of a blown head gasket ). Whats on at Santa pod this week end ?, I go quire regularly for the Drag Racing.

[Traci66]

Hi tony, he's just out with the car now, so I will get him to read this when he con back in, this weekend is PSV show or something like that.

[tonyav]

PSV ?

[Traci66]

Performance vauxhall, something like that, I'll ask him when he comes back in and let you know.

[tonyav]

Oh ok, not proper cars then lol.

[Traci66]

He is obsessed with vauxhalls. He has said that he think the fan is not kicking in and this may be linked to the thermostat, right or wrong?

[tonyav]

Could be yes, also there is a electrical sensor type thing on the actual radiator that tells the fan when to start and stop, could be a prob with that.

[Traci66]

All fluid levels seem to be fine, thing is he only usually does a journey in it of about five miles or so, so if it had been like that for a while he wouldn't have noticed, he says the thermostat is new, he thinks, only bought the car a few months ago.

[tonyav]

Get him to check the thermostat it could be dodgy, also check that the fan cuts in when the temp gauge is reading high. Has a last resort he can remove the thermostat altogether for his trip to santa pod, how many miles is from you ?.

[jake-the-peg]

When it's overheating is the radiator and pipes hot or cold?

If they're cold then it's probably a stuck thermostat

If they're warm but not as hot as you'd think you might have a water pump begining to fail.

Obviously as tony says check coolant levels and check for coolant in the oil

Low coolant could also be a small radiator hole.

Easy to tell if the fan's not kicking in open it when it's getting hot - only thing is I'd be surprised if it's overheating through lack of the fan when it's being driven and there's a flow of air across the radiator unless there's a lot of stop starting going on.

[Traci66]

Hi, he is just out there now checking everything you have both mentioned, it's about 130 miles from us tony, looks like they might just have to take the one car to Santa pod, think of the petrol money they'll save and they can share the driving then, daughter is going too.

[tonyav]

Yep as jake says check the top and bottom hoses. If top hose is cold / lukewarm thermostat is kaput.

[tonyav]

130 miles thats a nice little drive, 90 miles for me .

[Traci66]

Thanks guys, I will let you know.

[Traci66]

He took the thermostat out, cars is still overheating and fan won't kick in when the temp gauge is in red. What makes the fan kick in when the engine is getting hot? Please and thank you.

[Traci66]

Bump

[SpikeyBush]

I've had problems on several Vauxhalls in the past with the temp gauge giving mickey mouse readings. Sometimes it's the sensor that screws into the cylinder head, sometimes it's the gauge on the dash and sometimed it's the voltage regulator. That was particularly bad on the Viva and Chevette. One particular car cried wolf so many times that when it really was overheating I took no notice of it and warped the head.

[Andyvon]

The fan is operated by a bimetallic thermoswitch which screws into the body of the radiator. When the coolant reaches a certain temperature the switch turns the fan on to draw air through the radiator (eg. when sitting in traffic with no airflow through the radiator). Thermoswitches often fail Traci, then they suddenly won't switch the fan on. The temperature gauge then goes very high until the car starts moving forward and air passes through the radiator again. In that case, a new thermoswitch costs about £12-15. Your son will have to drain some coolant from the radiator then unscrew the old switch, fit the new one then top the coolant up again.

However, new thermoswitches can be defective. That was the case with my car a few years ago so I simply wired the fan directly to a switch I fitted on the dashboard. Now I just keep an eye on the temperature gauge then flick the fan on if I see the temperature start to rise in traffic.

If your son has removed the thermostat then the car should run much cooler than usual. If it's still overheating then I would suspect a blockage in the cooling system, either an airlock or just muck and rust. It could also be the radiator is very old and needs replacing, especially if it's been in the car since new. Places like Halfords do sell bottles of radiator flush fluid so that might be worth a try. Otherwise the problem will probably be solved by a new thermswitch or a new radiator.

Good luck.

[tonyav]

Traci, did he check to see if both the hoses on the radiator are hot or cold when the gauge is in the red. At normal operating temperature both the top and bottom hoses should get hot ( top one hot, bottom one cooler than the top ) the bottom hose will feel cooler than the top hose because the coolant has passed through the radiator. If the coolant is not flowing through the radiator then (a) it could be a blockage or an air lock or (b) the water pump is no good. And as far as the fan not kicking in, then as Andyvon says the thermo switch on the radiator is probably kaput.

[Traci66]

Let's see if I can get this right. He removed the thermostat and then stuck a piece of 30 amp fuse wire into some switch and the fan kicked in, he has drained the radiator and bought a new switch and thermostat, he is fitting them now. Thanks for the replies, will let you know when he's finished if its worked.