Sudden overheating - where would you start...?
Discussion
The engine was running at a perfect temperature until the last time I used the car. Now, the temperature is shooting up to high levels, forcing me to stop and let it cool down.
It's not weather-related - I used to keep the car in Spain and crawl through Spanish traffic without any probs!
Both fans are operating when it's up to temperature.
Any clues?
Thanks!
It's not weather-related - I used to keep the car in Spain and crawl through Spanish traffic without any probs!
Both fans are operating when it's up to temperature.
Any clues?
Thanks!
First check the coolant level from cold make sure there are no leaks.
I would then inspect the coolant system all hoses radiator for condition make sure Air is not getting in.
If all looks in good order take the thermostat out and put it in a pot of cold water and put it on the hob with a thermometer and see what Temperature it is opening at. or see if it even opens at all.
I would then inspect the coolant system all hoses radiator for condition make sure Air is not getting in.
If all looks in good order take the thermostat out and put it in a pot of cold water and put it on the hob with a thermometer and see what Temperature it is opening at. or see if it even opens at all.
First of all is it actually overheating?
Worth getting an infra red thermometer and checking the temperature of the rad and other parts of the cooling system. Not expensive from Maplins
Is the Rad getting hot? Thermostat not opening?
Is the return pipe cooler than the inlet pipe? Blocked core?
Are the fans kicking in?
Do you have pressure being released when you release the cap? If not then faulty pressure cap or a small leak.
Worth getting an infra red thermometer and checking the temperature of the rad and other parts of the cooling system. Not expensive from Maplins
Is the Rad getting hot? Thermostat not opening?
Is the return pipe cooler than the inlet pipe? Blocked core?
Are the fans kicking in?
Do you have pressure being released when you release the cap? If not then faulty pressure cap or a small leak.
Colin RedGriff said:
First of all is it actually overheating?
Worth getting an infra red thermometer and checking the temperature of the rad and other parts of the cooling system. Not expensive from Maplins
Is the Rad getting hot? Thermostat not opening?
Is the return pipe cooler than the inlet pipe? Blocked core?
Are the fans kicking in?
Do you have pressure being released when you release the cap? If not then faulty pressure cap or a small leak.
It's a good point - the engine did feel hotter, but that may have been an illusion having seen the temperature gauge rise rapidly!Worth getting an infra red thermometer and checking the temperature of the rad and other parts of the cooling system. Not expensive from Maplins
Is the Rad getting hot? Thermostat not opening?
Is the return pipe cooler than the inlet pipe? Blocked core?
Are the fans kicking in?
Do you have pressure being released when you release the cap? If not then faulty pressure cap or a small leak.
Not sure if the radiators were hot, but both fans were running, and when I went to check the fluid level having left it for ten minutes to cool a little, the cap was still under pressure, with plenty of fluid in there...
does it happen with the heater on hot and the fan on full? Do you have hot air from the heater? do the Rad fans both operate correctly? If so i would be checking thermostat then get a sniffer on the coolant to check for HG failier, if all is well get the rad recored as i could be blocked
bigdods said:
When you check the coolant you need to do it at the swirl pot not the expansion tank as this can be very deceiving.
Have you taken the big brass screw off the swirl pot ? It should be full up to the brim with coolant.
Thanks, I'll check that. She had been standing for a while...Have you taken the big brass screw off the swirl pot ? It should be full up to the brim with coolant.
slideways said:
does it happen with the heater on hot and the fan on full? Do you have hot air from the heater? do the Rad fans both operate correctly? If so i would be checking thermostat then get a sniffer on the coolant to check for HG failier, if all is well get the rad recored as i could be blocked
Thanks. Yes. I put heater on full heat and turned the interior fan on full to dissipate some of the heat. Both rad fans were running.What's HG failure?
I think he meant HC failure (hydrocarbons), if there are hydrocarbons present in the water system then you may have a Head gasket / liner problem. This tends to cause extra pressure in the water system as well, the extra pressure usually leads to air pockets, and the extra heat from cylinder gasses add to the overheating issue. If hydrocarbons are present ... I am afraid it is time to set a budget! sorry!
An otter switch on its way out can become unpredictable and cause the fans to come in later than normal and then shut off before they have done their cooling thing. Think it is about £20 to replace. Made all the difference on mine.
If everything mentioned above looks OK, is your rad original from new and is it working efficiently? (difficult to tell what the internal condition is I know).
If everything mentioned above looks OK, is your rad original from new and is it working efficiently? (difficult to tell what the internal condition is I know).
If both your main fans come on at the right temp and you have a hot heater then try undoing the coolant filler cap when stone cold!! if you have any pressure then could be a Head gasket, get a sniffer on it.
clicky
if all is well go for a new rad or recore
my 4.6 range rover had a slipped liner and a blocked rad so don't assume its only one thing or other it could be more than one!
clicky
if all is well go for a new rad or recore
my 4.6 range rover had a slipped liner and a blocked rad so don't assume its only one thing or other it could be more than one!
bigdods said:
When you check the coolant you need to do it at the swirl pot not the expansion tank as this can be very deceiving.
Have you taken the big brass screw off the swirl pot ? It should be full up to the brim with coolant.
Is it ok just to open the swirlpot ?Have you taken the big brass screw off the swirl pot ? It should be full up to the brim with coolant.
Sorry to hijack on this thread, but I've been reading intently as I've been getting erratic (albeit below 90deg) temps in my Chim
Coolant was low in the expansion tank, but wasn't sure if opening the brass topped swirlpot was ok and if it's low, can I fill from there ?
Cheers
Graeme
graeme4130 said:
Is it ok just to open the swirlpot ?
Sorry to hijack on this thread, but I've been reading intently as I've been getting erratic (albeit below 90deg) temps in my Chim
Coolant was low in the expansion tank, but wasn't sure if opening the brass topped swirlpot was ok and if it's low, can I fill from there ?
Cheers
Graeme
If your temp gauge is erratic it could mean air in the system.Sorry to hijack on this thread, but I've been reading intently as I've been getting erratic (albeit below 90deg) temps in my Chim
Coolant was low in the expansion tank, but wasn't sure if opening the brass topped swirlpot was ok and if it's low, can I fill from there ?
Cheers
Graeme
If this is the case you will need to top it up and bleed the system.
scotty_d said:
If your temp gauge is erratic it could mean air in the system.
If this is the case you will need to top it up and bleed the system.
Sorry if this sounds like a dumb question, but with a swirlpot system, I still just put the heater to hot, undo the bottom radiator plug, open the expansion tank filler then empty fully and then fill back up through the expansion tank filler until coming out the radiator plug and then do it up and fill 50% coolant then the rest water ?If this is the case you will need to top it up and bleed the system.
Or do I need to do something with the swirl pot too ?
Sorry for the numpty question
Ben,
As someone else has said, it could be the Otter switch breaking down and behaving erraticly, switching the fans on and off at the wrong times. Otter switches are relatively cheap I recently fitted Part No QH-XEFS20 (92/87) for £13.22
it switches the fans on at 92 and off at 87 degrees. Mine is located on the radiator and was a 5 minute job to replace and then bleed the coolant system as very little coolant came out when I replaced the switch - I kept the swirl pot and expansion tank caps on whilst replacing the Otter switch.
In combination with the Otter switch, you may well have a inefficient radiator - I had this and got mine re-cored - either sludged up or fins broken or seeping/leaking coolant. Have a look at the front of the rad through the grille/intake aperture - you may get a shock at the state of the front of the radiator matrix.
Graeme,
Are you asking about draining and re-filling the system or just bleeding the system?
The process for bleeding the sytem or topping up the coolant level is described in detail in the handbook.
HTH
Ged
As someone else has said, it could be the Otter switch breaking down and behaving erraticly, switching the fans on and off at the wrong times. Otter switches are relatively cheap I recently fitted Part No QH-XEFS20 (92/87) for £13.22
it switches the fans on at 92 and off at 87 degrees. Mine is located on the radiator and was a 5 minute job to replace and then bleed the coolant system as very little coolant came out when I replaced the switch - I kept the swirl pot and expansion tank caps on whilst replacing the Otter switch.
In combination with the Otter switch, you may well have a inefficient radiator - I had this and got mine re-cored - either sludged up or fins broken or seeping/leaking coolant. Have a look at the front of the rad through the grille/intake aperture - you may get a shock at the state of the front of the radiator matrix.
Graeme,
Are you asking about draining and re-filling the system or just bleeding the system?
The process for bleeding the sytem or topping up the coolant level is described in detail in the handbook.
HTH
Ged
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