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Discussion Starter #1
So, for the past few days I've been having a issue with my tf, when driving its seems to run cool the temperature gauge is just over a quarter on the gauge, when the car has been idling for a few minutes the gauge moves to just above half way before the rad fan kicks in and brings it back down,
FYI the heater works fine on hot.
 

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So, for the past few days I've been having a issue with my tf, when driving its seems to run cool the temperature gauge is just over a quarter on the gauge, when the car has been idling for a few minutes the gauge moves to just above half way before the rad fan kicks in and brings it back down,
FYI the heater works fine on hot.
I had a similar issue last year and because one of the rad hoses was on the cool side, went for a thermostat change. Big mistake. It was the gauge sender at fault. Its got a blue connector. A 5 minute job instead of many hours blindly feeling around under the inlet manifold to fit the thermostat in the rain. In January!
 

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mgf
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if the thermostat is stuck open it would take longer to warm up and also explain the temp gauge showing cooler at a quarter mark when driving as the increased air flow thru rad will bring the temperature down considerably. not sure about idling and the temp rising just above half way as from my experience the needle stays just below half even if the rad fan kicks in.
i personally would start with thermostat only because you said the temp lowers as you drive as the thermostat if working correctly would close when driving if the water temp is below 88c, dont think you should be seeing so much movement on temp gauge once its hit normal running temp which would be my concern if it was my car. also the temp gauge is delayed so that only major differences in temp are shown else it will be going up to normal then down to cold all the time.
not losing water? coolant pressuring ok?

keep us posted as there are alot of owners of here who are very helpful and have lots of experience.
cheers
 

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It does sound like the thermostat, from the description the temperature gauge and the fan seem to be in sync even though the two are on separate sensors and circuits. The other option is to bleed the coolant system as from the description there could be air in the system.
 

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mg_tf
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Before doing any parts changing, I would be attempting to get the actual running temperature measured first. This will establish whether you have a coolant temperature control issue, or simply a faulty sender or gauge problem.
 

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Discussion Starter #6
Before doing any parts changing, I would be attempting to get the actual running temperature measured first. This will establish whether you have a coolant temperature control issue, or simply a faulty sender or gauge problem.
Running temps are between 85-90 depending on the weather, When sat idling it will climb to 104 before the fan kicks in and brings it back down.
 

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Discussion Starter #7
It does sound like the thermostat, from the description the temperature gauge and the fan seem to be in sync even though the two are on separate sensors and circuits. The other option is to bleed the coolant system as from the description there could be air in the system.
I've bleed and bleed it and then again doesn't seem to be any air in the system, However today I did notice the the passenger side pipe for the rad is cool and the drivers side one is hot.
 

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mgf
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do you have prt fitted? i noticed you said passenger side rad pipe is cool and drivers hot? thats sounds like prt is fitted as without prt inlet to rad is passenger side and outlet is drivers side.
 

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Discussion Starter #9
do you have prt fitted? i noticed you said passenger side rad pipe is cool and drivers hot? thats sounds like prt is fitted as without prt inlet to rad is passenger side and outlet is drivers side.
On further investigation both rad pipes do get hot passenger side just seems to take longer to warm up, I have replaced the PRT today it's made no change .
 

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Has this always been the case or has the issue just started?

In the past some TF's with PRT have by some mechanics have put the conventional thermostat into the system thinking it had been removed meaning that both thermostats are fighting against each other.
 

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Discussion Starter #11
Has this always been the case or has the issue just started?

In the past some TF's with PRT have by some mechanics have put the conventional thermostat into the system thinking it had been removed meaning that both thermostats are fighting against each other.
This issue started recently.
 

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mgf
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sorry i am getting confused, can you confirm your concerns, is it the temp gauge movement ie: quarter when driving and then about half idling where before it never moved once car warmed up?
you havent said you are overheating or that you are losing water etc. apologies if these are stupid questions

cheers
 

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Discussion Starter #13
sorry i am getting confused, can you confirm your concerns, is it the temp gauge movement ie: quarter when driving and then about half idling where before it never moved once car warmed up?
you havent said you are overheating or that you are losing water etc. apologies if these are stupid questions

cheers
The car dose not get up to temp at all unless the heater is set to cold when idling then it's get hot all the way to 104c when the fan kicks in and brings it back down to mid 90s, I've replaced the PRT thermotstat, I don't seem to be losing coolant if anything the expansion bottle fills up completely, I'm confident the HG has blown as I seem to get water come out the exhaust,.
 

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mgf
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Have you got a return flow to the expansion tank? Have you checked both jiggle valves are not blocked.
 

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Discussion Starter #15
Have you got a return flow to the expansion tank? Have you checked both jiggle valves are not blocked.
All pipes seem to be clear and I have return to the expansion bottle, I checked the coolant level this morning and it smells strongly of petrol
 
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