New Chimaera & Overheating
Discussion
Looking at past discussions, this must be like de ja vu to many so my apologies in advance. I did read many of the threads and a lot of other stuff and came to some conclusions and would appreciate comment from more experienced people. I am a mechanical idiot and know nothing about TVR's. With kind help from this forum I am eagerly awaiting my very own copy of the "bible" which should be here in a few weeks. At the moment I don't even have an owner's manual. For he past eight years I have been driving Land Rovers (2.25 diesel, 2.5 TDi&TD5 diesel, 4.6 petrol Rover V8 and 4,4 petrol BMW V8) in Southern Africa, including extended desert trips, and have yet to cook one. OK, now that we have that out of the way :
1) Ambient is upper 20 to lower 30 Celcius here at the moment with an occasional day that may push into the 40 Celcius range. Temperature rarely if ever drops to freezing and then only during mid-winter nights.
2) Driving is bumber-to-bumber in the mornings with some open highway during the day. Car is garaged at night - not even close to freezing.
3) Car is a 2001 Chimaera 5.0 with a serpentine belt, no heater, has PS & AC and seems to have an aftermarket Unichip fitted and is very well maintained. 21 000 KM on the clock.
4) Idling temperature seem to be 90 Celcius at all times. It varies between 95 to 115 Celcius on the gauge when working hard. From what I read it is a bit high. Previous owner and TVR agents (Classic Sports Cars in Randburg, Gauteng) told me not to worry, but I still don't like it.
5) Coolant is greenish yellow, very clean and it looks like anti freexe is at fairly high concentration. (I will therefore assume it is 50% Ethylene Glycol mixed with normal tap water)
6) I bled he system to the best of my ability three times. (remember, no manual, no bible).
7) Fans cut in at exatly 90 Celcius on the gauge. Given our ambients I believe the modification that cuts in at an adjustable and lower temperature may help. Running fans at half speed at an even lower temp may further reduce the load. I ordered the modification that seems to accomplish this. Mod-Wise said "the top kit will do everthing you want, fully adjustable half speed cut in and fully adjustable full speed fans ...." Would like this verified and comment welcome.
8) Fans cut out immediately when the ignition is switched off. As I do quite a few trips to customers during the day, I believe there may be some advantage in getting the heat out of the system while parked between trips. I have been told that the mod above will do this. Mod-Wise said : "with of course fan run on" Would like to verfy this and comments welcome.
9) Both fans seem to run at the same speed. The voltage on the two fans are within 0.1 Volt of each other and within 0.2 Volt of battery voltage, so I assume no need for any mofifications here. However Mod-Wise said : "and in most cases a nice increase in fan speed" which in my opinion can only improve matters.
10) I temporarily fitted an additional temperature gauge. I ran the single wire probe through the clamp of the small rubber pipe that runs into the top of the swirl pot (I believe this is the silver upright cylinder thingy with the brass plug on top)and well into the swirl pot. This gauge registers about 67 Celcius at idle and never gets above about 75 Celcius even when the car works hard (with the gauge showing as much as 110 celcius).
11) The car gauge may be wrong, and I am not sure how to verify this - still thinking about it.
12) However, the fans cutting in at 90 celcius seem to indicate that the car gauge is right ....
13) So, if the temp in the swirl pot IS about 20 Celcius lower than in the engine (the probe can not be easily run into the engine - suggestions welcome), I THINK it means that the radiator and fans are coping but the system does not get the heat out of the engine fast enough. To me, this (possible) temperature diffirential implicates the water pump, coolant and/or thermostat ?
14) Given the condition of all the other components on the car, I feel confident that the water pump must still be OK.
15) If the mixture is the 50/50 Ethylene Glycol and tap water that I assume, it's not very efficient in getting the heat transferred to the radiator. There is little or no risk of freezing where I live. Therefore, this coming weekend I am going to replace the mixture with 20% Ethylene Glycol mixed with distilled, de-ionized water with a bottle of StayCool ( www.staycool.co.za ) added. StayCool seems to do what WaterWetter does. It is widely used in racing circles in South Africa. Although highly recomended on this forum, Water Wetter is not available locally. Unless somebody thinks this is a very BAD idea .... BTW the anti-freeze is only for anti-corosion.
16) With the water drained, I also want to check he thermostat. All tips on identifying, removing, testing and refitting it will be much appreaciated.
17) I am toying with the idea of drilling a hole in the thermostat while it is out. Opinions ? How big a hole should one drill.
Sorry about the long story. Any input welcome.
Cheers,
Willem
1) Ambient is upper 20 to lower 30 Celcius here at the moment with an occasional day that may push into the 40 Celcius range. Temperature rarely if ever drops to freezing and then only during mid-winter nights.
2) Driving is bumber-to-bumber in the mornings with some open highway during the day. Car is garaged at night - not even close to freezing.
3) Car is a 2001 Chimaera 5.0 with a serpentine belt, no heater, has PS & AC and seems to have an aftermarket Unichip fitted and is very well maintained. 21 000 KM on the clock.
4) Idling temperature seem to be 90 Celcius at all times. It varies between 95 to 115 Celcius on the gauge when working hard. From what I read it is a bit high. Previous owner and TVR agents (Classic Sports Cars in Randburg, Gauteng) told me not to worry, but I still don't like it.
5) Coolant is greenish yellow, very clean and it looks like anti freexe is at fairly high concentration. (I will therefore assume it is 50% Ethylene Glycol mixed with normal tap water)
6) I bled he system to the best of my ability three times. (remember, no manual, no bible).
7) Fans cut in at exatly 90 Celcius on the gauge. Given our ambients I believe the modification that cuts in at an adjustable and lower temperature may help. Running fans at half speed at an even lower temp may further reduce the load. I ordered the modification that seems to accomplish this. Mod-Wise said "the top kit will do everthing you want, fully adjustable half speed cut in and fully adjustable full speed fans ...." Would like this verified and comment welcome.
8) Fans cut out immediately when the ignition is switched off. As I do quite a few trips to customers during the day, I believe there may be some advantage in getting the heat out of the system while parked between trips. I have been told that the mod above will do this. Mod-Wise said : "with of course fan run on" Would like to verfy this and comments welcome.
9) Both fans seem to run at the same speed. The voltage on the two fans are within 0.1 Volt of each other and within 0.2 Volt of battery voltage, so I assume no need for any mofifications here. However Mod-Wise said : "and in most cases a nice increase in fan speed" which in my opinion can only improve matters.
10) I temporarily fitted an additional temperature gauge. I ran the single wire probe through the clamp of the small rubber pipe that runs into the top of the swirl pot (I believe this is the silver upright cylinder thingy with the brass plug on top)and well into the swirl pot. This gauge registers about 67 Celcius at idle and never gets above about 75 Celcius even when the car works hard (with the gauge showing as much as 110 celcius).
11) The car gauge may be wrong, and I am not sure how to verify this - still thinking about it.
12) However, the fans cutting in at 90 celcius seem to indicate that the car gauge is right ....
13) So, if the temp in the swirl pot IS about 20 Celcius lower than in the engine (the probe can not be easily run into the engine - suggestions welcome), I THINK it means that the radiator and fans are coping but the system does not get the heat out of the engine fast enough. To me, this (possible) temperature diffirential implicates the water pump, coolant and/or thermostat ?
14) Given the condition of all the other components on the car, I feel confident that the water pump must still be OK.
15) If the mixture is the 50/50 Ethylene Glycol and tap water that I assume, it's not very efficient in getting the heat transferred to the radiator. There is little or no risk of freezing where I live. Therefore, this coming weekend I am going to replace the mixture with 20% Ethylene Glycol mixed with distilled, de-ionized water with a bottle of StayCool ( www.staycool.co.za ) added. StayCool seems to do what WaterWetter does. It is widely used in racing circles in South Africa. Although highly recomended on this forum, Water Wetter is not available locally. Unless somebody thinks this is a very BAD idea .... BTW the anti-freeze is only for anti-corosion.
16) With the water drained, I also want to check he thermostat. All tips on identifying, removing, testing and refitting it will be much appreaciated.
17) I am toying with the idea of drilling a hole in the thermostat while it is out. Opinions ? How big a hole should one drill.
Sorry about the long story. Any input welcome.
Cheers,
Willem
Willem , can help with a couple of points.
The Mod Wise kit is very good and would recommend it & yes if you wire it up it will provide fan run on after the engine is turned off.
The temp gauges have a certain notoriety for not being fully accurate, or it could well be you have a faulty sendor or air pockets.
Have you filled the swirl tank up until the coolant is starting to exit via the bleed screw on the rad ?
Is it dumping any coolant from the expansion tank when it is showing the 100+ temps ?
Also, do you know if the car is fiited with the lower temp thermostat ?
The Mod Wise kit is very good and would recommend it & yes if you wire it up it will provide fan run on after the engine is turned off.
The temp gauges have a certain notoriety for not being fully accurate, or it could well be you have a faulty sendor or air pockets.
Have you filled the swirl tank up until the coolant is starting to exit via the bleed screw on the rad ?
Is it dumping any coolant from the expansion tank when it is showing the 100+ temps ?
Also, do you know if the car is fiited with the lower temp thermostat ?
I reply IN CAPITALS.
[quote=N17 TVR]Willem , can help with a couple of points.
Have you filled the swirl tank up until the coolant is starting to exit via the bleed screw on the rad ?
NO I HAVNT. ROUGHLY WHERE IS THE BLEED SCREW ?
Is it dumping any coolant from the expansion tank when it is showing the 100+ temps ?
WHERE WILL IT DUMP THE COLLANT ? I CANT FIND ANY "TRADITIONAL" RELEASE VALVE/CAP ANYWHERE ?
Also, do you know if the car is fiited with the lower temp thermostat ?
NO IDEA !
[quote=N17 TVR]Willem , can help with a couple of points.
Have you filled the swirl tank up until the coolant is starting to exit via the bleed screw on the rad ?
NO I HAVNT. ROUGHLY WHERE IS THE BLEED SCREW ?
Is it dumping any coolant from the expansion tank when it is showing the 100+ temps ?
WHERE WILL IT DUMP THE COLLANT ? I CANT FIND ANY "TRADITIONAL" RELEASE VALVE/CAP ANYWHERE ?
Also, do you know if the car is fiited with the lower temp thermostat ?
NO IDEA !
jtong said:
I'm not a mechanical wizard, but doesn't the antifreeze also RAISE the boiling point of the coolant? Not sure what effect reducing the concentration from 50% to 20% would have (particularly since you get REALLY hot weather).
I LOOKED AT SOME ARTICLES/WHITE PAPERS AND BOILING POINT ONLY RAISES MARGINALLY WHEN DECREASING ANTI-FREEZE CONCENTRATION FROM 50% to 20% WHILE THE HEAT CAPACITY/CONDUCTIVITY CHANGES SPECTACULARLY AS YOU LOWER IT FROM 50% TO 20%. FREEZING CHANGES MORE AS CONCENTRATION CHANGES, BUT FREEZING IS A MOOT POINT TO ME. MY GUT FEEL (AND I WILL ONLY KNOW AFTER THE WEEKEND) IS THAT WITH THE NEW MIXTURE, IT WILL HOPEFULLY NOW STAY FURTHER AWAY FROM BIOLING THAN WAS THE CASE BEFORE. FROM ARTICLES I READ, BOLING POINT MAY CHANGE BY AS LITTLE AS 2 CELCIUS, WHILE STAYCOOL CLAIMS 15% REDUCTION IN TEMPERATURE. WILL REPORT BACK.
Everything you've described points to an inaccurate gauge, but if I were you I would prefer to prove this rather than assume it.
The small rubber pipe you refered to is not in the main water flow and cannot be relied on to provide an accurate water temperature measurement. However, if you remove the brass plug and drop the probe right down inside the tank so it is immersed in water, you will get an accurate measurement. Obviously, running with the brass plug removed will mean the system is unpressurised. This is OK for static running, or for gentle pootling, but do not push the engine hard while it is unpressurised. If your engine really is overheating then this will allow it to boil, in other words if it does boil when you do this, you certainly do have an overheating problem and not just an inaccurate gauge.
I've used the Mod-Wise kit and it is excellently put together and very effective, and seems a very sensible upgrade under your conditions, regardless of whether you already have overheating problems.
The main point of drilling a hole in the stat is to improve venting so you do not get an air lock when you fill it up. It doesn't improve cooling. In cold climates it can cause over-cooling problems (because the stat can't completely stop water flow through the radiator) but I suspect that is not a problem that will trouble you!
When you bleed the system, remember to vent the radiator by the bleed screw in the top corner.
While you're doing your temperature measurements, check that the stat is opening correctly. You can do this by measuring the temperature in the swirl talk at the point the stat opens. (When the stat opens, the bottom of the radiator will suddenly go from cool/luke warm to very hot). If the stat seems to be opening too early, it is probably knackered in which case it may also not be opening fully - replace it.
I assume you have a splitter under the car behind the radiator inlet. If not, you might want to have it fitted.
You want to keep a good strong antifreeze concentration. It raises the boiling point and acts as a corrosion inhibitor. If you want to improve the heat transfer to water, consider using Water Wetter or a similar additive.
The small rubber pipe you refered to is not in the main water flow and cannot be relied on to provide an accurate water temperature measurement. However, if you remove the brass plug and drop the probe right down inside the tank so it is immersed in water, you will get an accurate measurement. Obviously, running with the brass plug removed will mean the system is unpressurised. This is OK for static running, or for gentle pootling, but do not push the engine hard while it is unpressurised. If your engine really is overheating then this will allow it to boil, in other words if it does boil when you do this, you certainly do have an overheating problem and not just an inaccurate gauge.
I've used the Mod-Wise kit and it is excellently put together and very effective, and seems a very sensible upgrade under your conditions, regardless of whether you already have overheating problems.
The main point of drilling a hole in the stat is to improve venting so you do not get an air lock when you fill it up. It doesn't improve cooling. In cold climates it can cause over-cooling problems (because the stat can't completely stop water flow through the radiator) but I suspect that is not a problem that will trouble you!
When you bleed the system, remember to vent the radiator by the bleed screw in the top corner.
While you're doing your temperature measurements, check that the stat is opening correctly. You can do this by measuring the temperature in the swirl talk at the point the stat opens. (When the stat opens, the bottom of the radiator will suddenly go from cool/luke warm to very hot). If the stat seems to be opening too early, it is probably knackered in which case it may also not be opening fully - replace it.
I assume you have a splitter under the car behind the radiator inlet. If not, you might want to have it fitted.
You want to keep a good strong antifreeze concentration. It raises the boiling point and acts as a corrosion inhibitor. If you want to improve the heat transfer to water, consider using Water Wetter or a similar additive.
Willem, a couple of points:
90 degrees is the right time for the fans to cut in, so your gauge may well be accurate.
My ('98 edition) of the bible says most recommendations for antifreeze are 25-30%, and that TVR recommend 33%. So in south africa you definitely don't need 50%!
With a serpentine engine, you have both a swirl pot (the one with the brass-looking screw cap) and an expansion tank (the one with the blue screw on cap). The blue pressure cap seals the system when screwed on tight - if it boils, water/steam will come out here.
Strongly recommend you wait for the bible before drilling holes in things - it includes a chapter on the cooling system including testing the thermostat and draining and refilling to avoid air pockets (tho' it sounds like you already know all about this, please don't take offence!)
edited to say, hadn't seen Greenv8s' reply when I typed mine - listen to him first, he knows a lot more than I do!
>> Edited by caro on Friday 21st January 12:09
90 degrees is the right time for the fans to cut in, so your gauge may well be accurate.
My ('98 edition) of the bible says most recommendations for antifreeze are 25-30%, and that TVR recommend 33%. So in south africa you definitely don't need 50%!
With a serpentine engine, you have both a swirl pot (the one with the brass-looking screw cap) and an expansion tank (the one with the blue screw on cap). The blue pressure cap seals the system when screwed on tight - if it boils, water/steam will come out here.
Strongly recommend you wait for the bible before drilling holes in things - it includes a chapter on the cooling system including testing the thermostat and draining and refilling to avoid air pockets (tho' it sounds like you already know all about this, please don't take offence!)
edited to say, hadn't seen Greenv8s' reply when I typed mine - listen to him first, he knows a lot more than I do!
>> Edited by caro on Friday 21st January 12:09
GreenV8S said:
Everything you've described points to an inaccurate gauge.......
I assume you have a splitter under the car behind the radiator inlet. If not, you might want to have it fitted.
Please elaborate on the splitter. Never heard of it. What am I looking for. What does it do ?
Please excuse the ignorance.
It's a metal strip just behind the air intake at the front of the car, that sticks out beneath the car and encourages air to go into the air intake rather than straight under the car. You would need to kneel down and squint underneath to see it. I expect a search of PH would turn up pictures of it.
Is your TVR fitted with an oil cooler as standard?
If over-heating or high running temperatures due to summer conditions in SA are a problem, you might like to consider fitting one as an additional way of removing some heat from the engine.
Keeping TVR engines cool in the UK can be a problem as the cooling system seems to be just adequate when everything is in tip top condition. So in SA things can only be that much worse.
If over-heating or high running temperatures due to summer conditions in SA are a problem, you might like to consider fitting one as an additional way of removing some heat from the engine.
Keeping TVR engines cool in the UK can be a problem as the cooling system seems to be just adequate when everything is in tip top condition. So in SA things can only be that much worse.
GreenV8S said:
It's a metal strip just behind the air intake at the front of the car, that sticks out beneath the car and encourages air to go into the air intake rather than straight under the car. You would need to kneel down and squint underneath to see it. I expect a search of PH would turn up pictures of it.
Hi Willem
See here for pics of the splitter...
www.pistonheads.com/gassing/topic.asp?p=2&f=8&t=127807&h=0
'Muggs'
willem
I have had my Chimaera, same spec as yours, in the heat of Hong Kong with slow moving traffic for 8 years now and hope the following is useful:
1. Throw away the theromstat until the cooler weather arrives.
2. Fit a lower temp otter switch. Mine came from a Honda and starts the fans at about 70*c.
3 Wrap the exhaust manifold in a heat resistant cloth where it exits the heads and goes foreward and down in front of the engine.
4. Forget the splitter. It is expensive and only works at high speed and comes off on every speed bump and or lumps in the road.
5. Make sure that there is a rubber seal between the rad and the body.
6. Position the number plate as far away from the grill as possible.
7. Fit 2 extra fans in front of the rad that have a manual switch. This can be adapted easily to allow a timed delay after engine shutdown.
8. You may have starting difficulties when the engine gets very hot. It appears that there is absolutely nothing when switching on. When it cools it is as nothing was wrong. It is the starter motor, either shield it or fit a starter relay. TVR removed this relay!!.
9. Use a high temp coolant with the a/freeze inhibitor rather than water.
10. Buy a new temp sensor as it sounds yours is not reading correctly.
11. Renew the Blue rad cap.
12. Speed reduces the temp under the bonnet. Unless you go really silly!!!
I have had my Chimaera, same spec as yours, in the heat of Hong Kong with slow moving traffic for 8 years now and hope the following is useful:
1. Throw away the theromstat until the cooler weather arrives.
2. Fit a lower temp otter switch. Mine came from a Honda and starts the fans at about 70*c.
3 Wrap the exhaust manifold in a heat resistant cloth where it exits the heads and goes foreward and down in front of the engine.
4. Forget the splitter. It is expensive and only works at high speed and comes off on every speed bump and or lumps in the road.
5. Make sure that there is a rubber seal between the rad and the body.
6. Position the number plate as far away from the grill as possible.
7. Fit 2 extra fans in front of the rad that have a manual switch. This can be adapted easily to allow a timed delay after engine shutdown.
8. You may have starting difficulties when the engine gets very hot. It appears that there is absolutely nothing when switching on. When it cools it is as nothing was wrong. It is the starter motor, either shield it or fit a starter relay. TVR removed this relay!!.
9. Use a high temp coolant with the a/freeze inhibitor rather than water.
10. Buy a new temp sensor as it sounds yours is not reading correctly.
11. Renew the Blue rad cap.
12. Speed reduces the temp under the bonnet. Unless you go really silly!!!
All,
Thanx for all the help amd suggestions. I answer "in bulk".
1) The car has a "splitter" fitted (now that I know what it is.
2) Put in high performance "racing" coolant.
3) Tested the thermostat. It works, but opens later and smaller than a new one. Fitted a new one - 74 Celcius.
4) Still bleeding off air - about 10l coolant in now.
5) Very definate but little improvement in temperature.
6) Now going for new temp sender unit. IS IT A STANDARD LR PART. DOES ANYBODY HAVE PART NUMBER ?
7) Waiting for an upgrade kit from mod-wise - thanx Dave.
Regards,
Willem
Thanx for all the help amd suggestions. I answer "in bulk".
1) The car has a "splitter" fitted (now that I know what it is.
2) Put in high performance "racing" coolant.
3) Tested the thermostat. It works, but opens later and smaller than a new one. Fitted a new one - 74 Celcius.
4) Still bleeding off air - about 10l coolant in now.
5) Very definate but little improvement in temperature.
6) Now going for new temp sender unit. IS IT A STANDARD LR PART. DOES ANYBODY HAVE PART NUMBER ?
7) Waiting for an upgrade kit from mod-wise - thanx Dave.
Regards,
Willem
david beer said:
You can not have too much cooling capacity, speak to Tim at ACT for a very nice uprated alloy rad. I have never had a problem but as my rad has holed, i have ordered an alloy one.
David,
Putting an anorak on:
The Conduction coefficient (k) of Copper (Annealed) is: 2715
Conduction coefficient (k) of Aluminum is: 1420
Ratio is 1.91:1 (almost 2:1)
Copper is more efficient at transfer of heat.
However, Copper is approximately twice the price of Aluminum.
So I hope your "upgrade" is at least 2:1 bigger in size otherwise you may not achieve your "...can not have too much cooling...."
Cheers
Trev McM
Despite that, aluminium radiators normally do offer significantly better cooling than a copper/brass radiator of the same size. Invariably for automotive applications where money is no object, aluminium radiators are used in preference to copper/brass.
Possibly to do with the fact that the thermal conductivity of brass is roughly a third that of copper, and also that aluminium is mechanically stronger than copper so it can be thinner, increasing the cooling. Most 'aluminium' radiators are made of alloy rather than pure aluminium. The higher the stresses the thicker the material has to be and the higher the alloy content has to be. Both these measures reduce the cooling capability of the radiator, so the actual effectiveness will vary from application to application. But even a poor alloy radiator will provide significantly improved cooling compared to a similar sized copper/brass one.
Setting aside the choice of material, the OEM radiators were originally design for their mud clearing capability and have a very coarse matrix. Aftermarket radiators have a much finer matrix and are thinner, giving less air resistance and more air flow as well as better conduction between air and water.
Possibly to do with the fact that the thermal conductivity of brass is roughly a third that of copper, and also that aluminium is mechanically stronger than copper so it can be thinner, increasing the cooling. Most 'aluminium' radiators are made of alloy rather than pure aluminium. The higher the stresses the thicker the material has to be and the higher the alloy content has to be. Both these measures reduce the cooling capability of the radiator, so the actual effectiveness will vary from application to application. But even a poor alloy radiator will provide significantly improved cooling compared to a similar sized copper/brass one.
Setting aside the choice of material, the OEM radiators were originally design for their mud clearing capability and have a very coarse matrix. Aftermarket radiators have a much finer matrix and are thinner, giving less air resistance and more air flow as well as better conduction between air and water.
Phew,
i thought i had wasted me money, reading the first post Trev! You would buy the rad for its looks alone, they fit it on 500BHP racers and claim they are the bees knees ! I dont think Tim(ACT) would put his HUGE reputation on a product that would dissapoint. Like a big kid, im actually looking forward to trying it !
i thought i had wasted me money, reading the first post Trev! You would buy the rad for its looks alone, they fit it on 500BHP racers and claim they are the bees knees ! I dont think Tim(ACT) would put his HUGE reputation on a product that would dissapoint. Like a big kid, im actually looking forward to trying it !
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