Cooler running

Cooler running

Author
Discussion

latham91

Original Poster:

101 posts

102 months

Thursday 21st July 2016
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Hi all,

Noticed the engine temperature getting up a bit the other day through town and then when I got home I let it idle to see if the fans would cut in/out and control the temperture. They did cut in/out and there was some control but the temperture on the dash board gauge was eventually showing 105C and also 103C on Rovergauge at which point I switched off to let things cool down. I do have a manual fan over ride button under the dash but it would be nice for the engine to regulate itself a bit better. I was wondering whether to change the thermostat (where the top hose goes in to the top of the inlet manifold at the front of the engine?) and also the otter switch (mine is on the n/s of the radiator) to both let more flow through the radiator and also switch the fans on earlier. Has anyone got any recommendations for this?

I think the radiator and general cooling works OK since when I use the over ride switch to put the fans on constantly they bring the temperture down nicely.
Mines a bog standard 400 on a T-plate by the way...

Thanks, Ed

QBee

20,904 posts

143 months

Thursday 21st July 2016
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Was all this in the current heat wave?
Mine has been doing very similar this week

Topper_Harley

147 posts

105 months

Thursday 21st July 2016
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Same here except the wires close to the otter switch have melted so I was right!

latham91

Original Poster:

101 posts

102 months

Thursday 21st July 2016
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It was last Saturday - not especially hot ambient, say 25 degrees? I didn't take it out on Tuesday when it was over 30....

WOO5IE

931 posts

196 months

Friday 22nd July 2016
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10 years ago when I first got my Chim you could get a a lower running temp kit from Levens which had a lower operating otter switch 84degrees I think and a lower temp stat I think 74 degrees plus some coolant additive (wetter)which has long since gone

The stat and otter are still in place . I do here a fan override switch as well but I never use it.

These lower temp items are still available. It doesn't run too cool in winter either.
At the time I did a lot of research and there were other benefits to a cooler running engine as well.

Hope this helps

Edited by WOO5IE on Friday 22 July 22:47

bobfather

11,171 posts

254 months

Friday 22nd July 2016
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The dash gauge reading via the Rover gauge mod means very little, it depends on the resistor you added to the link and that resistor is only to correct the temperature at normal running temperature. Oh and even if it were 105degC it would not be boiling, coolant water/antifreeze mix has a higher boiling point and liquid under pressure has a higher boiling point. My guess is it was hot but the gauge was not reading correctly at that point on the scale

QBee

20,904 posts

143 months

Friday 22nd July 2016
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It's at least more accurate than the temp gauge on any of my daily drivers. They go quickly up to the exact mid-point of the gauge and stay there regardless of whether it's motorway speed at -15 degrees outside, or traffic jam in Rome in mid-summer

JimTC

270 posts

216 months

Friday 22nd July 2016
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Yes, why is that the temp gauge on Chimaeras varies so much when compared with your daily driver?

I would have thought the temperature ought to rise until the thermostat opens and allows radiator cooling and that the system would the self regulate unless under excess load, i.e. thermostat closes as temperature falls, re-opens as it rises etc.. Of course, accepting that there are occasions when the temperature will rise if there is insufficient cooling air flowing through the radiator when stationary in traffic with, ultimately, the fans cutting in to bring the temp down.

Thanks

WOO5IE

931 posts

196 months

Friday 22nd July 2016
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Apart from having a large V8 in a fibre glass engine bay and very hot manifolds in there as well.
It is the siting of the temp sensor that feeds the gauge . A lot of people use the spare unused sensor that is by the dizzy for more stable readinds

QBee

20,904 posts

143 months

Friday 22nd July 2016
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JimTC said:
Yes, why is that the temp gauge on Chimaeras varies so much when compared with your daily driver?

I would have thought the temperature ought to rise until the thermostat opens and allows radiator cooling and that the system would the self regulate unless under excess load, i.e. thermostat closes as temperature falls, re-opens as it rises etc.. Of course, accepting that there are occasions when the temperature will rise if there is insufficient cooling air flowing through the radiator when stationary in traffic with, ultimately, the fans cutting in to bring the temp down.

Thanks
Its because the temp gauge on your daily driver is a complete con.
It may look like a linear analogue dial, but it actually is a needle with just three positions - "off", "running" and "fked". whistle

trev4

736 posts

161 months

Friday 22nd July 2016
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Have you flushed the system lately you can get a build up of sludge in the system, mine never goes over 90 even on a very hot track day on Monday

PhilH42

690 posts

101 months

Friday 22nd July 2016
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I've just had a new ally rad, new blue silicon hoses, temp sensor, pump, 74 deg stat and fans cutting in earlier as it would get to just over 100 degrees on the gauge quickly when in traffic.....now........still gets to 100 on the gauge when in traffic.....bloody gauge!

Still it does look nice cool

Bassfiendnoideawhathp

5,530 posts

249 months

Friday 22nd July 2016
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QBee said:
Its because the temp gauge on your daily driver is a complete con.
It may look like a linear analogue dial, but it actually is a needle with just three positions - "off", "running" and "fked". whistle
thumbup

latham91

Original Poster:

101 posts

102 months

Friday 22nd July 2016
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Hi, yes, flushed it out last year and it does cool down once one the move or when the fans come on. Think i,m tempted to put a 74 degree thermostat in and see what effect it has.
Looks like tvr parts do one at a reasonable price.

kennybgr8

379 posts

141 months

Friday 22nd July 2016
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How big a job is it to put a switch on the system to activate the fans or override them if needed, what wires do you need to tap into, no technical answers please plain and simple works for me,,,

ClassiChimi

12,424 posts

148 months

Friday 22nd July 2016
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I've always been under the impression if everything in the cooling system is operating as it should, override switches ar'nt necessary, is that nieve?

if the fans kick in and out as they should then surely the waters staying within temperature limits,,,, or is that nieve too.
I had to drive through Coventry at 4.30pm yesterday in oppressive heat, about 40 mins of stop start and very slow moving traffic, temp gauge steady at 80 but eventually getting near 95 and then quickly coming back down to 70 when on the move, I do have an alley rad which I think helps,, even though the gauge was reading high, fans kicked in and out only when slow or stationary and as thats set at around 88 I conclude the water temps were never that high,,, is that freaking nieve too? wink

I'm also running MBE ECU and my temp gauge has been much steadier since the install, it used to fluctuate between 70 and 105 before and wandered far more.
It now usually goes upto 70 when moving and then 80 if in town and stays there,,, my feeling is the gauge reads about 7 degrees low until heat soak gets to it and then it's anyone's guess!
My fans often kick in when the gauge is at 80,
It's a minefield, I just go by the fans kicking in as that's the signal from the Ecu suggesting the engines around 88-90 degrees.

If your fans are not going off then I'd be concerned.


kennybgr8

379 posts

141 months

Saturday 23rd July 2016
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I have had issues for a while now regarding the fans but have been unable to get working on the car for a few months but that is going to change shortly, and try to get to the bottom of a few problems the fans and not operating being one of them,,,

QBee

20,904 posts

143 months

Saturday 23rd July 2016
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kennybgr8 said:
I have had issues for a while now regarding the fans but have been unable to get working on the car for a few months but that is going to change shortly, and try to get to the bottom of a few problems the fans and not operating being one of them,,,
Most likely sources of that problem are the otter switch and the fan wiring connectors. Five minute job to check.

First thing to check is that your otter switch is still working. On later cars it is on the back of the radiator, passenger side, brass switch. On earlier cars it is on the bottom of the swirl pot. Run the engine up to 90 on the temp gauge and see if the fans kick in. If they don't, stop the engine, pull the terminals off the otter switch, bridge across the two terminals with a paperclip or similar, so as to bypass the switch, then turn on the ignition. Fans should kick straight in.

If that doesn't resolve it, or if only one fan kicks in, the next check is the wiring connectors close to the fans themselves. Just trace the wires from each fan and find the white plastic connectors that lie beneath the rad. Clean up the contacts and then see if that improves things with the otter switch still bypassed. Also, having done that, cable tie the cables to the front chassis bar to keep them out of the rainwater than can collect below the rad.

Then replace the wires onto the otter switch (doesn't matter which way round) and run the engine up to temp to check you have completed the job.

ray von

2,913 posts

251 months

Saturday 23rd July 2016
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ClassiChimi said:
I've always been under the impression if everything in the cooling system is operating as it should, override switches ar'nt necessary, is that nieve?
You are correct, however the override switch is invaluable if your otter switch decides to pack up one day and you need the fans on.

BeastMaster

443 posts

186 months

Saturday 23rd July 2016
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Hi Guys – this is my cooling experience.

My car is a 500 which I bought 12 years ago and all the doom mongers and info said that cooling on these cars was always compromised and would overheat in traffic. The car is a 94 and had been modded with the later cowling and larger twin fans.

In the first 10 years driving in normal conditions the temp was always around the 90, sitting in traffic in hot weather just above by 1 or 2 mm and just below in normal. When moving it would be 3 to 4 mm below unless cold weather and would be just above 70.

2 years ago noticed a change and the temp was running a little higher, and had to start topping up with a small amount of water every 500miles or so. Found the problem with the weep hole in the pump but hard to notice during the monthly car inspection. - new pump problem solved and back to normal.

Last year while sitting in traffic on hot day the temp started rising, fans came on as normal but temp steadily rises approaching 100 so switched off and allowed to cool. No water loss and continued on my way.. After taking advisement and against my better judgment decided to fit a lower thermost apart from running a little cooler on the move made no difference to the normal running temp, but at odd times still had the overheating problem when stuck in traffic.

This then started happening more frequently so decided to investigate, my first thought was the rad which wast now over 20 years old, and on removing the cowl and grill found a good 25% of the matrix was F***, really surprised it had managed to keep the car running and no leaks.

Lots of talk about Ali Rads etc, but because had no issues before and a little concerned about reducing front end weight and altering the balance of the car decided on a re-core, good value for money and no worries about lining up fittings etc on a replacement.

Can report the car is now back to having no concerns regarding cooling, have not changed the thermostat back to standard but will do next time I change the coolant. The one change which has happened is that the heater works a lot better, previously it had always been rubbish, had tried in the past to improve it by bleeding and flushing, decided not to take it out as a complete pain.

A few notes and observations.

No need for any special hoses, coolant, rads or bypass switches for normal road use – just keep everything in good condition.

Make sure the rubber seal around the fan cowl is good, it tends to degrade in the heat of the engine bay and allow air to bleed out, reducing the air pressure the fans can draw through the rad, a small thing which make a big difference to efficiency.

In cold weather I now add a blind to the front of the rad to keep temp up while on the move as it runs a little cold, this may change when I put the normal thermostat back in.

Have considered, as the only mod fitting a timer to the otter switch, so that after turning off the engine on a very hot day and a long run, can fire up the fans for say 5mins to reduce under bonnet temp, this being my only concern, that something could get damaged by the heat soak after turning off.

Andy