fluctuating temp guage

ROVERX501 · 22nd April 2012, 16:25

Hi,

I was not going to ask about this problem, but I have just read another post about poor fuel economy, and one answer given was the engine was not running at the proper temp.
So this where I come in, my temp gauge climbs very slowly and when it reaches half way it drops to quarter if I am travelling on a open road at 55/60 MPH, then goes back up slowly if I come to slow moving traffic, and back down in fast moving traffic. The computer reads I am doing 18.2 MPG

no matter where I am

.

So is this cold running affecting MPG? Engine is 2.5 auto by the way.

Thanks.

Matt V6 · 22nd April 2012, 18:41

Hi

I too have experianced this problem too, on the motorway.

I thought this was a common thing connected to the fan maybe, to keep the engine cool at high speeds.

Any further info welcome.

Matt

T-Cut · 22nd April 2012, 18:50

This thread is discussing the same thing: http://www.the75andztclub.co.uk/foru...d.php?t=111642

TC

David3807 · 22nd April 2012, 20:06

Sounds like a thermostat stuck open or partially open.

scorpio stu · 23rd April 2012, 18:14

Mine does exactly the same and I'm at a loss as to what to do.

scorpio stu · 23rd April 2012, 18:17

Quote:

Originally Posted by David3807

Sounds like a thermostat stuck open or partially open.

If it's stuck open or partially open does it need replacing ?

SD1too · 24th April 2012, 07:26

These symptoms could indicate a faulty thermostat. If so, it will need to be replaced. The other possibility is that the cooling system is not pressurising properly due perhaps to a leak or faulty expansion tank cap. In this case, when in traffic or in hot ambient conditions, the engine may show signs of overheating. To check this, monitor the coolant temperature using the instrument pack diagnostics. If the cooling system has been drained recently there's also the possibility of an air lock, particularly with the V6 if the expansion tank hasn't be raised during refilling.

Simon.

22nd April 2012, 16:25	#1
ROVERX501 Avid contributor Rover 75 2.5 Auto Saloon Join Date: Feb 2012 Location: Durham Posts: 149 Thanks: 3 Thanked 0 Times in 0 Posts	fluctuating temp guage Hi, I was not going to ask about this problem, but I have just read another post about poor fuel economy, and one answer given was the engine was not running at the proper temp. So this where I come in, my temp gauge climbs very slowly and when it reaches half way it drops to quarter if I am travelling on a open road at 55/60 MPH, then goes back up slowly if I come to slow moving traffic, and back down in fast moving traffic. The computer reads I am doing 18.2 MPG no matter where I am. So is this cold running affecting MPG? Engine is 2.5 auto by the way. Thanks.

23rd April 2012, 18:14	#5
scorpio stu This is my second home Jaguar 3.2 Executive Join Date: Feb 2011 Location: Buckhurst Hil Posts: 3,269 Thanks: 508 Thanked 154 Times in 116 Posts	Mine does exactly the same and I'm at a loss as to what to do. __________________ Current cars V8 Petrol Range Rover Kia Sportage Hybrid Triumph Street Triple R

24th April 2012, 07:26	#7
SD1too Doesn't do things by halves Rover 75 2.5 Connoisseur Auto (1999) Dealer launch model. Join Date: Mar 2007 Location: Former Middlesex Posts: 20,366 Thanks: 1,587 Thanked 3,749 Times in 3,181 Posts	These symptoms could indicate a faulty thermostat. If so, it will need to be replaced. The other possibility is that the cooling system is not pressurising properly due perhaps to a leak or faulty expansion tank cap. In this case, when in traffic or in hot ambient conditions, the engine may show signs of overheating. To check this, monitor the coolant temperature using the instrument pack diagnostics. If the cooling system has been drained recently there's also the possibility of an air lock, particularly with the V6 if the expansion tank hasn't be raised during refilling. Simon. __________________ "Whatever is rightly done, however humble, is noble." Sir Henry Royce.

22nd April 2012, 18:41	#2
Matt V6 Avid contributor MG6 Ocean Blue Join Date: Mar 2012 Location: Dudley Posts: 241 Thanks: 55 Thanked 6 Times in 6 Posts	Hi I too have experianced this problem too, on the motorway. I thought this was a common thing connected to the fan maybe, to keep the engine cool at high speeds. Any further info welcome. Matt

22nd April 2012, 18:50	#3
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 thread is discussing the same thing: http://www.the75andztclub.co.uk/foru...d.php?t=111642 TC

22nd April 2012, 20:06	#4
David3807 Posted a thing or two 2002 R75 Conn SE 2.5l Auto Tourer, 2001 R75 Conn SE 2.5 Auto Saloon Join Date: Nov 2006 Location: Gravesend Posts: 1,897 Thanks: 0 Thanked 2 Times in 2 Posts	Sounds like a thermostat stuck open or partially open.