Cooling problems

Shide · 17th February 2019, 16:40

I seemingly have cooling problems. Symptoms are temperature gauge inoperable, fluctuating idle speed from 1500-2000 rpm. fan comes on full blast after a couple of minutes idling. I thought the thermostat in the lower hose might be jammed shut. Have changed it and it has made no difference. Any ideas? I'm dreading something like water pump failure. Typically this happened a DAY before the MOT.

Yorkshire GOC · 17th February 2019, 17:01

Have you run the onboard diagnostics to see your real time coolant temperature with the engine running / driving - have you checked your fan is working properly - do the Demist test - your fan resistor may have packed in meaning the low speed fan will not work. See link below re the onboard diagnostics.

https://www.the75andztclub.co.uk/for...38&postcount=1

marinabrian · 17th February 2019, 18:17

It is a defective coolant temperature sensor, or the associated wiring

Brian

T-Cut · 17th February 2019, 18:35

This has happened to me a couple of times and caused a bit of panic the first time. Most likely the sensor connector plug has got grimed up and not making good contact on the sensor pins. Here it is just under the head coolant outlet.

TC

Shide · 17th February 2019, 19:27

Thanks T-cut, will check that. Yorkshire GOC, I know that low speed fan does not work but I've been driving the car without any issues previously.

Shide · 18th February 2019, 18:48

You know that thing when your PC packs up, 'Have you tried switching it off and on again?' Well it was that simple to restore order in the car. Unplugged the sensor pin, gave it wipe, plugged it back in.

Shide · 19th February 2019, 09:56

In the course of sorting this I noticed that when draining the coolant it was a mucky beige colour with a few globules of 'mayo'. Is oil working its way into the cooling system? Oil doesn't appear to be affected.

T-Cut · 19th February 2019, 19:36

Quote:

Originally Posted by Shide

In the course of sorting this I noticed that when draining the coolant it was a mucky beige colour with a few globules of 'mayo'. Is oil working its way into the cooling system? Oil doesn't appear to be affected.

Has there been any history of HGF?

If so it's probably remanants of contamination from an earlier event.

Whether it actually means something more worrying will be a matter of regularly monitoring the new coolant for any oily film in the header tank, floating globules and such.

SD1too · 19th February 2019, 21:55

Quote:

Originally Posted by Shide

I know that low speed fan does not work but I've been driving the car without any issues previously.

Carl,

That is very unwise. Your coolant temperature could rise to 112 degrees C without you being aware. That is too hot. I strongly recommend that you repair your faulty fan. If it's a case of an open circuit silver resistor, what's stopping you?

Simon

Shide · 20th February 2019, 13:18

Ahem....nothing really. It's just in a long list of 'things to do'!

17th February 2019, 16:40	#1
Shide Avid contributor Rover 75 1.8T Join Date: Jun 2015 Location: Ash Vale Posts: 133 Thanks: 5 Thanked 13 Times in 10 Posts	Cooling problems I seemingly have cooling problems. Symptoms are temperature gauge inoperable, fluctuating idle speed from 1500-2000 rpm. fan comes on full blast after a couple of minutes idling. I thought the thermostat in the lower hose might be jammed shut. Have changed it and it has made no difference. Any ideas? I'm dreading something like water pump failure. Typically this happened a DAY before the MOT.

17th February 2019, 17:01	#2
Yorkshire GOC I really should get out more....... Rover 75 connoisseur se v6 auto Join Date: May 2014 Location: Hull Posts: 2,063 Thanks: 1,842 Thanked 623 Times in 469 Posts	Have you run the onboard diagnostics to see your real time coolant temperature with the engine running / driving - have you checked your fan is working properly - do the Demist test - your fan resistor may have packed in meaning the low speed fan will not work. See link below re the onboard diagnostics. https://www.the75andztclub.co.uk/for...38&postcount=1 __________________ She came off the Longbridge Line on 20-05-2003 The Silver Machine was the 13th of 160 Rover 75's to come off the production line that day and is the 100th of 527 Starlight Silver Rover 75 2.5 V6 Connoisseur SE Auto saloons listed in the build records produced world wide.

17th February 2019, 19:27	#5
Shide Avid contributor Rover 75 1.8T Join Date: Jun 2015 Location: Ash Vale Posts: 133 Thanks: 5 Thanked 13 Times in 10 Posts	Temp sensor Thanks T-cut, will check that. Yorkshire GOC, I know that low speed fan does not work but I've been driving the car without any issues previously.

18th February 2019, 18:48	#6
Shide Avid contributor Rover 75 1.8T Join Date: Jun 2015 Location: Ash Vale Posts: 133 Thanks: 5 Thanked 13 Times in 10 Posts	Fixed! You know that thing when your PC packs up, 'Have you tried switching it off and on again?' Well it was that simple to restore order in the car. Unplugged the sensor pin, gave it wipe, plugged it back in.

19th February 2019, 09:56	#7
Shide Avid contributor Rover 75 1.8T Join Date: Jun 2015 Location: Ash Vale Posts: 133 Thanks: 5 Thanked 13 Times in 10 Posts	Further to this? In the course of sorting this I noticed that when draining the coolant it was a mucky beige colour with a few globules of 'mayo'. Is oil working its way into the cooling system? Oil doesn't appear to be affected.

17th February 2019, 18:17	#3
marinabrian MG ZT Join Date: Jan 2011 Location: Newcastle Upon Tyne Posts: 20,151 Thanks: 3,565 Thanked 10,837 Times in 5,718 Posts	It is a defective coolant temperature sensor, or the associated wiring Brian

17th February 2019, 18:35	#4
T-Cut This is my second home Rover75 and Mreg Corsa. Join Date: Nov 2006 Location: Sumweer onat mote o'dust (Sagin) Posts: 21,752 Thanks: 341 Thanked 3,660 Times in 2,924 Posts	This has happened to me a couple of times and caused a bit of panic the first time. Most likely the sensor connector plug has got grimed up and not making good contact on the sensor pins. Here it is just under the head coolant outlet. TC

20th February 2019, 13:18	#10
Shide Avid contributor Rover 75 1.8T Join Date: Jun 2015 Location: Ash Vale Posts: 133 Thanks: 5 Thanked 13 Times in 10 Posts	Fan Ahem....nothing really. It's just in a long list of 'things to do'!