75 1.8T Temperature Gauge Cool

Marriott · 29th April 2014, 20:44

Hi, I have a 2003 Rover 75 1.8T SE petrol with about 56,000 miles on the clock. I had the head gasket done in 2011. Just after that there were a few coolant leaks as some tubes burst but once all leaks were plugged it's run very smoothly and quietly and still is today. I also had the problem of the temperature gauge dropping to zero a few years ago and got that replaced. That's the history, anyway a few months ago I noticed when I was doing 80 or 90 particularly downhill the temperature gauge would drop slightly from 9 oclock to about 7 or 8 o clock but when I got back to a normal speed it went back to 9. Today I noticed that nearly the entire motorway journey it was on 8 oclock, the faster I went the cooler the gauge got but when I idle or do 30 it's always bang on at 9 oclock. Anyone else seen this specific issue ?

Thanks

lovema75 · 29th April 2014, 20:48

Welcome!

It sounds very much like a stuck thermostat, i.e its sticking open too much and allowing too much coolant circulation.

lovema75 · 29th April 2014, 20:50

Forgot to mention that you would be better driving in diagnostic, and see the correct real-time temp, rather than rely on the notoriously unreliable guage.

T-Cut · 29th April 2014, 22:06

Pasted across from your other thread.

The temperature gauge tells you very little about what's actually going on. It's important to know that the 'normal' mark on the dial is first reached at a mere 75C, which is well below what is regarded as the normal running temperature. As the engine warms up to the typical 90-95C running band, the gauge stays put. If you had a coolant leak leading to an overheat, you wouldn't know about it till the engine reaches 115C, when the needle will begin to rise very quickly. If the overheat goes to 120-125C or maybe a lot more, it hits the red line. Not very helpful knowing the engine may have just cooked!

Likewise, over-cooling won't be seen until the engine cools to below 75C. The needle will then fall, as yours does. Clearly it goes well below 75C on those occasions suggesting the ram effect on the radiator is overcoming any effect the thermostat may have in keeping the temperature 'normal'. In other words the stat needs changing.

If you'd like to know what the temperature actually is, drive with the trip screen in diagnostic mode.

Diagnostic Mode: http://www.the75andztclub.co.uk/foru...ad.php?t=55585

After you've got the hang of it, you need section 7.1.

TC

29th April 2014, 20:44	#1
Marriott Newbie Rover 75 Join Date: Apr 2014 Location: Oxford Posts: 1 Thanks: 0 Thanked 0 Times in 0 Posts	75 1.8T Temperature Gauge Cool Hi, I have a 2003 Rover 75 1.8T SE petrol with about 56,000 miles on the clock. I had the head gasket done in 2011. Just after that there were a few coolant leaks as some tubes burst but once all leaks were plugged it's run very smoothly and quietly and still is today. I also had the problem of the temperature gauge dropping to zero a few years ago and got that replaced. That's the history, anyway a few months ago I noticed when I was doing 80 or 90 particularly downhill the temperature gauge would drop slightly from 9 oclock to about 7 or 8 o clock but when I got back to a normal speed it went back to 9. Today I noticed that nearly the entire motorway journey it was on 8 oclock, the faster I went the cooler the gauge got but when I idle or do 30 it's always bang on at 9 oclock. Anyone else seen this specific issue ? Thanks

29th April 2014, 22:06	#4
T-Cut This is my second home Rover75 and Mreg Corsa. Join Date: Nov 2006 Location: Sumweer onat mote o'dust (Sagin) Posts: 21,753 Thanks: 341 Thanked 3,660 Times in 2,924 Posts	Pasted across from your other thread. The temperature gauge tells you very little about what's actually going on. It's important to know that the 'normal' mark on the dial is first reached at a mere 75C, which is well below what is regarded as the normal running temperature. As the engine warms up to the typical 90-95C running band, the gauge stays put. If you had a coolant leak leading to an overheat, you wouldn't know about it till the engine reaches 115C, when the needle will begin to rise very quickly. If the overheat goes to 120-125C or maybe a lot more, it hits the red line. Not very helpful knowing the engine may have just cooked! Likewise, over-cooling won't be seen until the engine cools to below 75C. The needle will then fall, as yours does. Clearly it goes well below 75C on those occasions suggesting the ram effect on the radiator is overcoming any effect the thermostat may have in keeping the temperature 'normal'. In other words the stat needs changing. If you'd like to know what the temperature actually is, drive with the trip screen in diagnostic mode. Diagnostic Mode: http://www.the75andztclub.co.uk/foru...ad.php?t=55585 After you've got the hang of it, you need section 7.1. TC Last edited by T-Cut; 29th April 2014 at 22:09..

29th April 2014, 20:48	#2
lovema75 This is my second home 75 Tourer CDT Join Date: Dec 2011 Location: Enfield Posts: 3,925 Thanks: 63 Thanked 431 Times in 237 Posts	Welcome! It sounds very much like a stuck thermostat, i.e its sticking open too much and allowing too much coolant circulation.

29th April 2014, 20:50	#3
lovema75 This is my second home 75 Tourer CDT Join Date: Dec 2011 Location: Enfield Posts: 3,925 Thanks: 63 Thanked 431 Times in 237 Posts	Forgot to mention that you would be better driving in diagnostic, and see the correct real-time temp, rather than rely on the notoriously unreliable guage.