chim running hot - the fun begins!
Discussion
hi guys, chims off road till spring - so time to get all the jobs done.The car runs very very hot all the time.
On a motorway run - it will sit at an indicated 95-100. The fans cut in when they should but dont really manage to achive much, is by the time I get the car in the garage - its dangerousuly high.
SO where to start.
I took my radiator out to a specialist and they are going to check flow etc - but seemed to think it was likely to be ok?
They suggested water pump or stat - so took water pump out and all looked like new.
Took stat out - which was only about 500 miles old and the correct TVR item- again looked ok and tested ok in pan of water.
Will be getting the rad back next week with the outcome... should that be found to be ok - where from here?
On a motorway run - it will sit at an indicated 95-100. The fans cut in when they should but dont really manage to achive much, is by the time I get the car in the garage - its dangerousuly high.
SO where to start.
I took my radiator out to a specialist and they are going to check flow etc - but seemed to think it was likely to be ok?
They suggested water pump or stat - so took water pump out and all looked like new.
Took stat out - which was only about 500 miles old and the correct TVR item- again looked ok and tested ok in pan of water.
Will be getting the rad back next week with the outcome... should that be found to be ok - where from here?
The gauge may not be that accurate,could also be the sender.
You tested the thermostat (there are two different temps used, 74 & 82 degrees)if you are using 82 try the other instead.
Have you tried running the engine with thermostat out to get an idea if water is circulating (as mentioned, possible air lock).Should give a significant temperature difference.
It could also be down to air circulation. The chin spoiler which is missing off most cars, I think they can improve matters by drawing the warm air out (so I'm told anyhow).
Or you could try getting pre-cats removed, this should also bring down under-bonnet temperatures without effecting your MOT.
I will say I'm no expert, but I hope the suggestions help.
You tested the thermostat (there are two different temps used, 74 & 82 degrees)if you are using 82 try the other instead.
Have you tried running the engine with thermostat out to get an idea if water is circulating (as mentioned, possible air lock).Should give a significant temperature difference.
It could also be down to air circulation. The chin spoiler which is missing off most cars, I think they can improve matters by drawing the warm air out (so I'm told anyhow).
Or you could try getting pre-cats removed, this should also bring down under-bonnet temperatures without effecting your MOT.
I will say I'm no expert, but I hope the suggestions help.
After the fans had cut in did you feel the radiator to see how cool it was? Could you feel the air being drawn through it? Have you checked the fins to make sure they're clear and allowing pleny of air to flow through the rad, were the fans running at the right speed (i.e. were they spinning quickly and blasting air). Was it the same temp across the whole radiator?
Is this a new occurance, if so what has changed - why did you change the thermostat 500 miles ago?
Where is your gauge measuring the temperature, where TVR placed it or on the old Rover sender unit? If it is on the old RR sender did you put the variable resistor in place and set the gauge correctly when it was moved there?
When was the coolant last changed, what colour is it? What's the specific gravity?
When did you last check your pressure cap?
I know that seems like a lot and a bit of an interrogation but I just jotted them down as I thought of them...
Is this a new occurance, if so what has changed - why did you change the thermostat 500 miles ago?
Where is your gauge measuring the temperature, where TVR placed it or on the old Rover sender unit? If it is on the old RR sender did you put the variable resistor in place and set the gauge correctly when it was moved there?
When was the coolant last changed, what colour is it? What's the specific gravity?
When did you last check your pressure cap?
I know that seems like a lot and a bit of an interrogation but I just jotted them down as I thought of them...
If your rad is original and is out of the car, you may want to consider a recore? Probably less than £150 from where your up to already.
The other 'cheap' fix could well be changing the otter switch which is usually screwed in to the rad - £20. If this is original, then as they break down they become unreliable and shut the fans off before they have really had chance to cool the system. I replaced mine and the temps are much more stable and sit at around 75oC on the move and 85 in town. Again the temp guage probably isn't exact but will non the less give you an idea of where your at.
Does your system ever loose fluid and need filling up? Mine use to need about half a pint every month and was eventualy traced to a crack on the rad within the metal casing and was invisible to the naked eye. Since been re-cored I havn't had to put any water in it over the last 6 months. When the old rad was removed I could see how inefficient it had become because all the metal fins were breaking down.
Hope you get is sorted. You could always run it during the winter only!
The other 'cheap' fix could well be changing the otter switch which is usually screwed in to the rad - £20. If this is original, then as they break down they become unreliable and shut the fans off before they have really had chance to cool the system. I replaced mine and the temps are much more stable and sit at around 75oC on the move and 85 in town. Again the temp guage probably isn't exact but will non the less give you an idea of where your at.
Does your system ever loose fluid and need filling up? Mine use to need about half a pint every month and was eventualy traced to a crack on the rad within the metal casing and was invisible to the naked eye. Since been re-cored I havn't had to put any water in it over the last 6 months. When the old rad was removed I could see how inefficient it had become because all the metal fins were breaking down.
Hope you get is sorted. You could always run it during the winter only!
chrisdurham said:
On a motorway run - it will sit at an indicated 95-100. The fans cut in when they should but dont really manage to achive much, is by the time I get the car in the garage - its dangerousuly high.
As has been mentioned - first step would be to check that the gauge is actually reading correctly.Something like this is useful for checking temperatures Link
At what temperature are they cutting in (is that read from your gauge or from an independent source)? If your car is really running at 95-100 that would imply they are are on all the time. If they are on but not managing to reduce the temperature then the efficiency of the cooling system needs to be looked at.
pearly said:
The gauge may not be that accurate,could also be the sender.
The chin spoiler which is missing off most cars, I think they can improve matters by drawing the warm air out (so I'm told anyhow).
I may be wrong ( I usually am), but I was advised to fit a chin spoiler after the bonnet on mine popped open at 135mph on a track day. The reason was to reduce the amount of air going through the engine bay, and hence forcing the bonnet to bow and pop open. It was also supposed to improve front end stability. I was advised that the car would probably run a bit hotter as a result.The chin spoiler which is missing off most cars, I think they can improve matters by drawing the warm air out (so I'm told anyhow).
hello, wow a lot of replies, I will try and answer them all:
No, not tried running with no stat yet, that would have to wait till next year when its back on the road.
Yes, I could buy another stat and try that.
Pre-cats are also out of mine
yes fins seem pretty clear and fans are certainly spinning very very fast.
History wise the car was running very cold all the time and also very rich. so I am undoing all the issues. I assumed the old stat was knackered so I replaced along with the fan switch.
My chim is a 93 and it is reading temp from the stock position.I couldnt find the bit where people do the RR mod (mines is a pre serp) maybe its on there on mine?
Coolant again only a few months old, waterways look very clean inside where the waterpump goes
Never checked the pressure cap, assumed ok as i wasnt getting any leakage?
I was quite keen to get a re-core - the specialist that has the rad is reviewing it right now - should get feedback shortly - id have no probs getting re-core if that was issue.
Doesnt seem to loose coolant
Yes testing that the gauge is reading correctly is a good idea - where should I point the laser while taking the reading?
I will check what the stat is rated at also, and measure it again using a thermometer.
Mines is pre serp, so a basic belt routing on mine
No, not tried running with no stat yet, that would have to wait till next year when its back on the road.
Yes, I could buy another stat and try that.
Pre-cats are also out of mine
yes fins seem pretty clear and fans are certainly spinning very very fast.
History wise the car was running very cold all the time and also very rich. so I am undoing all the issues. I assumed the old stat was knackered so I replaced along with the fan switch.
My chim is a 93 and it is reading temp from the stock position.I couldnt find the bit where people do the RR mod (mines is a pre serp) maybe its on there on mine?
Coolant again only a few months old, waterways look very clean inside where the waterpump goes
Never checked the pressure cap, assumed ok as i wasnt getting any leakage?
I was quite keen to get a re-core - the specialist that has the rad is reviewing it right now - should get feedback shortly - id have no probs getting re-core if that was issue.
Doesnt seem to loose coolant
Yes testing that the gauge is reading correctly is a good idea - where should I point the laser while taking the reading?
I will check what the stat is rated at also, and measure it again using a thermometer.
Mines is pre serp, so a basic belt routing on mine
chrisdurham said:
hi guys, chims off road till spring - so time to get all the jobs done.The car runs very very hot all the time.
On a motorway run - it will sit at an indicated 95-100. The fans cut in when they should but dont really manage to achive much, is by the time I get the car in the garage - its dangerousuly high.
SO where to start.
I think the 2nd paragraph of your description above is interesting. Most Chims[well mine at least] will run between 70 and 80 degrees at motorway speeds, even on the hottest of summer days.On a motorway run - it will sit at an indicated 95-100. The fans cut in when they should but dont really manage to achive much, is by the time I get the car in the garage - its dangerousuly high.
SO where to start.
Again "Most Chims" will have the fans kicking in at approx 92 and off at approx 88 degrees, so with the temps you quote above your fans must be constantly on.
If your fans are on and in your words "dont achieve much" then is the hot water flowing around/through the radiator? I would suspect not.
If it isnt an air lock then its possible your rad is blocked or partially blocked, because at motorway speeds there is more than enough air going thru the rad to bring the temp down.
Have the rad recored,fit a new thermostat,and a new otter switch while the system is empty.Refill and carefully bleed the system.
When your happy that everything is perfect, fit a fan overide switch. This isnt to solve any cooling issues, its just for "piece of mind" and the next time you are stuck in traffic, switch the fans on early and relax as the temp gauge should never go much higher than 90 to 95 tops, no matter how long your stuck there for.
Edited by TJC46 on Tuesday 4th December 21:51
Another chance for me to thank Colin RedGriff for selling me a rad with a 'slight weep' (so slight I've never found it).
I diagnosed head gasket failure on my AJP8, but when I saw the fire rings there was no sign of a leak. When I put Colin's used rad in my car the overheating was banished - it's just a shame I'd spent 5 months replacing the head gaskets first.
Verdict - do the easy cheap fixes first, even the ones you've discounted.
I diagnosed head gasket failure on my AJP8, but when I saw the fire rings there was no sign of a leak. When I put Colin's used rad in my car the overheating was banished - it's just a shame I'd spent 5 months replacing the head gaskets first.
Verdict - do the easy cheap fixes first, even the ones you've discounted.
hello guys,
just off the phone to the radiator people - after flow checking and cleaning it through, they conclude it is fine and not the source of my problem.
What the procedure for bleeding the system on these?
Heres my plan of attack once everything is fitted back:
Check temp on stat - fit colder if required -
check stat operation against thermometer -
Get lazer gun and check temp otter switch is opening - this is brand new so should be fine -
Check how accurate the dash gauge is and replace the temp sender anyway
just off the phone to the radiator people - after flow checking and cleaning it through, they conclude it is fine and not the source of my problem.
What the procedure for bleeding the system on these?
Heres my plan of attack once everything is fitted back:
Check temp on stat - fit colder if required -
check stat operation against thermometer -
Get lazer gun and check temp otter switch is opening - this is brand new so should be fine -
Check how accurate the dash gauge is and replace the temp sender anyway
chrisdurham said:
What the procedure for bleeding the system on these?
Heres a few tried and tested methods, can depend on serp or pre serp engines.http://www.pistonheads.com/gassing/topic.asp?h=0&a...
Your plan of attack seems very sensible to me.
Some good tips from Cider Andy on bleeding the cooling system here:
http://www.pistonheads.com/gassing/topic.asp?h=0&a...
And if you want to do the RR sender mod, the details are here:
http://www.pistonheads.com/gassing/topic.asp?t=118...
Some good tips from Cider Andy on bleeding the cooling system here:
http://www.pistonheads.com/gassing/topic.asp?h=0&a...
And if you want to do the RR sender mod, the details are here:
http://www.pistonheads.com/gassing/topic.asp?t=118...
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