Overheating, any suggestions?
Discussion
Hi All,
Went for a drive in my 450 today and it started overheating!
Symptoms:
-Temp slowly climbing past 100c whether in traffic or moving
- No heat from the interior fan
- No obvious coolant leaks
Any ideas? Just waiting for the car to cool down before I go and check anything obvious. I'm thinking stuck thermostat although it had a new one last year.
Went for a drive in my 450 today and it started overheating!
Symptoms:
-Temp slowly climbing past 100c whether in traffic or moving
- No heat from the interior fan
- No obvious coolant leaks
Any ideas? Just waiting for the car to cool down before I go and check anything obvious. I'm thinking stuck thermostat although it had a new one last year.
Sounds like it's lost some coolant. Could be a pin hole in a hose or the rad, a leaky hose or shhhh, a head gasket.
Turn the heater to hot, let the engine cool and remove the water filler cap. Start her up and fill the system. See how much she takes, and then go for a run and check the levels again.
I had a new rad in my Hyundai I40, drove it for four months, no issues at all, then suddenly one day the temp gauge starting flickering from hot to middle to three quarters, etc. Checked the expansion tank, all normal, right between mid and max. Took the filler cap off the rad and started it up. She took two litres of coolant! Garage checked her over could find no leaks, pressure tested the system, all good. Been fine ever since.
So yes, airlocks can and do sometimes work their way out apparently!
Turn the heater to hot, let the engine cool and remove the water filler cap. Start her up and fill the system. See how much she takes, and then go for a run and check the levels again.
I had a new rad in my Hyundai I40, drove it for four months, no issues at all, then suddenly one day the temp gauge starting flickering from hot to middle to three quarters, etc. Checked the expansion tank, all normal, right between mid and max. Took the filler cap off the rad and started it up. She took two litres of coolant! Garage checked her over could find no leaks, pressure tested the system, all good. Been fine ever since.
So yes, airlocks can and do sometimes work their way out apparently!
Hi All,
Thanks for the replies! Yes it has cooled down
It was very low on coolant - I added about 3 litres to get it back up to full. No obvious leaks and no mayo on the disptick or expansion tank so maybe it was just a large airlock? Very strange the cooling system has not been touched since June ish.
Thanks for the replies! Yes it has cooled down
It was very low on coolant - I added about 3 litres to get it back up to full. No obvious leaks and no mayo on the disptick or expansion tank so maybe it was just a large airlock? Very strange the cooling system has not been touched since June ish.
Thing is, a pin hole can lose a lot of coolant under pressure yet dry up very quickly when the engine is stopped because of the heat. Particularly under the bonnet of a Chimaera.
Let us know how it develops. Like you say, might just be an airlock. I was amazed at my Hyundai. I thought airlocks were fairly immediate to manifest themselves. Clearly not!
Let us know how it develops. Like you say, might just be an airlock. I was amazed at my Hyundai. I thought airlocks were fairly immediate to manifest themselves. Clearly not!
Shed TVR said:
Hi All,
Thanks for the replies! Yes it has cooled down
It was very low on coolant - I added about 3 litres to get it back up to full. No obvious leaks and no mayo on the disptick or expansion tank so maybe it was just a large airlock? Very strange the cooling system has not been touched since June ish.
If it's lost 3 litres it must have been messy! Did you not see steam? When my Chimaera lost its coolant the otter switch was busticated and the water came out as steam and was very obvious.Thanks for the replies! Yes it has cooled down
It was very low on coolant - I added about 3 litres to get it back up to full. No obvious leaks and no mayo on the disptick or expansion tank so maybe it was just a large airlock? Very strange the cooling system has not been touched since June ish.
If not expelled as steam surely must be a leak. Good luck with the diagnosis! (Does the horn still work? On some Chims at least one of the fans is on the same fuse as the horn)
Loubaruch said:
Thanks for this will check that also.2 sMoKiN bArReLs said:
Were the fans cutting in?
Yes, and I checked both of them are coming on. Tyre Smoke said:
Thing is, a pin hole can lose a lot of coolant under pressure yet dry up very quickly when the engine is stopped because of the heat. Particularly under the bonnet of a Chimaera.
Let us know how it develops. Like you say, might just be an airlock. I was amazed at my Hyundai. I thought airlocks were fairly immediate to manifest themselves. Clearly not!
Yeah I think I need to get a pressure test done on it, I did find quite a lot of the hose clamps loose so have nipped them all up, hopefully that might stop any leaks. Let us know how it develops. Like you say, might just be an airlock. I was amazed at my Hyundai. I thought airlocks were fairly immediate to manifest themselves. Clearly not!
2 sMoKiN bArReLs said:
If it's lost 3 litres it must have been messy! Did you not see steam? When my Chimaera lost its coolant the otter switch was busticated and the water came out as steam and was very obvious.
If not expelled as steam surely must be a leak. Good luck with the diagnosis! (Does the horn still work? On some Chims at least one of the fans is on the same fuse as the horn)
I did see some steam when it overheated but not 3 litres worth, in my opinion anyway. I think it had already dropped in level before it overheated. Both fans still kicking in so I think everything with that is OK. If not expelled as steam surely must be a leak. Good luck with the diagnosis! (Does the horn still work? On some Chims at least one of the fans is on the same fuse as the horn)
As said as you have lost a lot of coolant the more likely cause is a leak, How long has your radiator been in the car? I managed to get through several before altering the bottom supports with springs. The radiators generally leak at the bottom corner due to twisting of the chassis. but as also said above a small leak will tend to evaporate with the heat so can be difficult to spot. When the leak gets worse you can usually see the evidence under the radand on the floor.
Your water pump has two seals on the shaft. There is a small hole in the water pump casing in between these two seals.
If the first seal is breached water will drip out that hole when under pressure.
Look for evidence of a sticky substance on your chassis cross bracing underneath the engine as a tell tale sign.
There will be very little evidence from above. If it’s been leaking from there you might see a dried trickle line right below that hole but don’t bank on it.
I’d take the car for a run and fully upto temp, keep engine running then look for leaks under the car as soon as you pull up.
As mentioned above rads corrode at the base so also look for leaks there.
If the first seal is breached water will drip out that hole when under pressure.
Look for evidence of a sticky substance on your chassis cross bracing underneath the engine as a tell tale sign.
There will be very little evidence from above. If it’s been leaking from there you might see a dried trickle line right below that hole but don’t bank on it.
I’d take the car for a run and fully upto temp, keep engine running then look for leaks under the car as soon as you pull up.
As mentioned above rads corrode at the base so also look for leaks there.
Shed TVR said:
Hi All,
Thanks for the replies! Yes it has cooled down
It was very low on coolant - I added about 3 litres to get it back up to full. No obvious leaks and no mayo on the disptick or expansion tank so maybe it was just a large airlock? Very strange the cooling system has not been touched since June ish.
3 litres is going to be more than an airlock. Thanks for the replies! Yes it has cooled down
It was very low on coolant - I added about 3 litres to get it back up to full. No obvious leaks and no mayo on the disptick or expansion tank so maybe it was just a large airlock? Very strange the cooling system has not been touched since June ish.
In addition to what's already been suggested, check whether the 'tray' under the rad is damp, hoses/connections (if silicon, clamps are not unknown to leak after some use), check the hose/inlet on the expansion tank as sometimes gets blocked with 'crud', new expansion cap. I'm sure you'd have spotted it by now but check carpets, particularly passenger side, for dampness (heater matrix, heater hoses/joints). Any dampness on top of the valley gasket? - if so, that can sometimes 'disappear' to the rear without being too obvious.
Do you still have the original 'S'-bend metal hose from rad lower outlet back up and over chassis, they can corrode with minor pin prick holes - stainless replacements are available.
Unless it's really obvious, it's going to be a gradual process of elimination. Can't remember but has thermostat been mentioned?
TarquinMX5 said:
3 litres is going to be more than an airlock.
Not necessarily. If he's had the heater 'off' all summer then it could be. I wouldn't discount it.But tend to agree with you and CC, likely a leak rather than an airlock.
What's the capacity of the cooling system?
It is five and a half litres in my Hyundai and that took two litres that had been hiding somewhere!
The capacity from dry is closer to 12 litres to fill.
You need to bleed the system IMO if you have added 3 litres and go from there.
I do believe jacking the front of the car up helps remove air from the heater matrix as you slowly fill with bleed hole at inlet manifold open. Just saves having to remove that air on warm up. Air will be in the system until it’s bled anyway but this helps remove a lot of it in the first place.
You need to bleed the system IMO if you have added 3 litres and go from there.
I do believe jacking the front of the car up helps remove air from the heater matrix as you slowly fill with bleed hole at inlet manifold open. Just saves having to remove that air on warm up. Air will be in the system until it’s bled anyway but this helps remove a lot of it in the first place.
There is one other possibility if you really cannot find the leak under pressure.
You might just have a porous block.
I had this problem, lost a couple of litres of water without warning and had the temperature fluctuation issues you describe.
The solution was a three stage sealant kit, cost about £100, worked.
Ask if you need further details - I don't have them to hand but can find out what it was if needed.
But it's much more likely that you have a leak somewhere.
You might just have a porous block.
I had this problem, lost a couple of litres of water without warning and had the temperature fluctuation issues you describe.
The solution was a three stage sealant kit, cost about £100, worked.
Ask if you need further details - I don't have them to hand but can find out what it was if needed.
But it's much more likely that you have a leak somewhere.
Loubaruch said:
As said as you have lost a lot of coolant the more likely cause is a leak, How long has your radiator been in the car? I managed to get through several before altering the bottom supports with springs. The radiators generally leak at the bottom corner due to twisting of the chassis. but as also said above a small leak will tend to evaporate with the heat so can be difficult to spot. When the leak gets worse you can usually see the evidence under the radand on the floor.
It had a new radiator about a year ago so shouldn't be an issue I hope! No evidence of leaks around there.Classic Chim said:
Your water pump has two seals on the shaft. There is a small hole in the water pump casing in between these two seals.
If the first seal is breached water will drip out that hole when under pressure.
Look for evidence of a sticky substance on your chassis cross bracing underneath the engine as a tell tale sign.
There will be very little evidence from above. If it’s been leaking from there you might see a dried trickle line right below that hole but don’t bank on it.
I’d take the car for a run and fully upto temp, keep engine running then look for leaks under the car as soon as you pull up.
As mentioned above rads corrode at the base so also look for leaks there.
Thanks for the advice, had a look while it's running and nothing obvious in these spots.If the first seal is breached water will drip out that hole when under pressure.
Look for evidence of a sticky substance on your chassis cross bracing underneath the engine as a tell tale sign.
There will be very little evidence from above. If it’s been leaking from there you might see a dried trickle line right below that hole but don’t bank on it.
I’d take the car for a run and fully upto temp, keep engine running then look for leaks under the car as soon as you pull up.
As mentioned above rads corrode at the base so also look for leaks there.
TarquinMX5 said:
3 litres is going to be more than an airlock.
In addition to what's already been suggested, check whether the 'tray' under the rad is damp, hoses/connections (if silicon, clamps are not unknown to leak after some use), check the hose/inlet on the expansion tank as sometimes gets blocked with 'crud', new expansion cap. I'm sure you'd have spotted it by now but check carpets, particularly passenger side, for dampness (heater matrix, heater hoses/joints). Any dampness on top of the valley gasket? - if so, that can sometimes 'disappear' to the rear without being too obvious.
Do you still have the original 'S'-bend metal hose from rad lower outlet back up and over chassis, they can corrode with minor pin prick holes - stainless replacements are available.
Unless it's really obvious, it's going to be a gradual process of elimination. Can't remember but has thermostat been mentioned?
The tray is damp however I'm pretty sure it's spray from the road due to the weather. There's evidence of leaks at some of the joints but I think this has happened when it's overheated as I did see steam coming from a few places. I've nipped the hose clamps up anyway. Heater hoses - I've had issues getting these to seal in the passenger footwell but it hasn't leaked 3 litres worth. Valley gasket I haven't checked yet - will have a look. S bend has been replaced with a stainless item. In addition to what's already been suggested, check whether the 'tray' under the rad is damp, hoses/connections (if silicon, clamps are not unknown to leak after some use), check the hose/inlet on the expansion tank as sometimes gets blocked with 'crud', new expansion cap. I'm sure you'd have spotted it by now but check carpets, particularly passenger side, for dampness (heater matrix, heater hoses/joints). Any dampness on top of the valley gasket? - if so, that can sometimes 'disappear' to the rear without being too obvious.
Do you still have the original 'S'-bend metal hose from rad lower outlet back up and over chassis, they can corrode with minor pin prick holes - stainless replacements are available.
Unless it's really obvious, it's going to be a gradual process of elimination. Can't remember but has thermostat been mentioned?
Tyre Smoke said:
Not necessarily. If he's had the heater 'off' all summer then it could be. I wouldn't discount it.
But tend to agree with you and CC, likely a leak rather than an airlock.
What's the capacity of the cooling system?
It is five and a half litres in my Hyundai and that took two litres that had been hiding somewhere!
I have been thinking about this post. I think just before it overheated I put the heater to hot for the first time since it was initally filled up, I wonder if it has had an airlock ever since it was filled up the first time and has taken until now to cause an issue?But tend to agree with you and CC, likely a leak rather than an airlock.
What's the capacity of the cooling system?
It is five and a half litres in my Hyundai and that took two litres that had been hiding somewhere!
Classic Chim said:
The capacity from dry is closer to 12 litres to fill.
You need to bleed the system IMO if you have added 3 litres and go from there.
I do believe jacking the front of the car up helps remove air from the heater matrix as you slowly fill with bleed hole at inlet manifold open. Just saves having to remove that air on warm up. Air will be in the system until it’s bled anyway but this helps remove a lot of it in the first place.
I'm pretty certain mine did not take 12 litres to fill up from being totally empty, also filled it on level ground so that was a mistake on my part. You need to bleed the system IMO if you have added 3 litres and go from there.
I do believe jacking the front of the car up helps remove air from the heater matrix as you slowly fill with bleed hole at inlet manifold open. Just saves having to remove that air on warm up. Air will be in the system until it’s bled anyway but this helps remove a lot of it in the first place.
QBee said:
There is one other possibility if you really cannot find the leak under pressure.
You might just have a porous block.
I had this problem, lost a couple of litres of water without warning and had the temperature fluctuation issues you describe.
The solution was a three stage sealant kit, cost about £100, worked.
Ask if you need further details - I don't have them to hand but can find out what it was if needed.
But it's much more likely that you have a leak somewhere.
Interesting, I'll see how I progress and let you know if I need more information thanks!You might just have a porous block.
I had this problem, lost a couple of litres of water without warning and had the temperature fluctuation issues you describe.
The solution was a three stage sealant kit, cost about £100, worked.
Ask if you need further details - I don't have them to hand but can find out what it was if needed.
But it's much more likely that you have a leak somewhere.
TarquinMX5 said:
Out of interest, when was the coolant level last checked, was it just prior to the most recent drive?
Before it overheated, honestly not since June most likely. So it did have a lot of time to loose fluid, however thinking about it I didn't have the issue until I turned the temperature controls to hot. Well I had the car up to temperature yesterday and checked as much as I could for leaks, nothing obvious and no steam under the bonnet. I'll check some of the spots people have mentioned here later today. At the moment I'm thinking it may have just been an airlock as unlikely as it seems.
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