Temperature guage fluctuating - Page 2

Simon · 4th December 2006, 22:41

Hi Patch, and welcome to the club!

Don't know how long it'll be until some one more important than me gives you an official welcome (you've hidden yourself well in this thread on this area of the forum

), but you can consider yourself welcomed from me!

GreyGhost · 5th December 2006, 09:43

Quote:

Originally Posted by Simon D

Hi Patch, and welcome to the club!

Don't know how long it'll be until some one more important than me gives you an official welcome (you've hidden yourself well in this thread on this area of the forum

), but you can consider yourself welcomed from me!

There's no one more important than anybody else here, we are all members of the same club. Some of us just help out a bit and purport to know where everything is.

Welcome to the club Patch enjoy your stay

courier118 · 5th December 2006, 14:41

At last someone with the same problem.........sorry.........I knew the maximum and minimum marks were there but thanks.Ive vacuum filled till im blue in the face............had it running with no cap on to let air draw out.........checked levels last night and today..............sitting bang on the maximum mark..............guage still all over the place between halfway and the next mark down...............i dont know whether theres air in it causing hot spots in the engine.......heater works fine...........whether its the temp sensor,faulty thermostat,faulty guage.When the cars been idling for a while the guage is at the halfway mark and the cooling fan cuts in..............im going to look for my axe soon and chop the damn thing up.......or may just go out and buy that 6.0ltr V8 vauxhall/holden monaro i like

DeeCee · 5th December 2006, 16:24

What about trying the old fashioned way of bleeding the system.

The cooling system runs at pressure to increase the boiling point of the water(antifreeze mixture)
The pressure is about 5 to 10PSI, normally controlled by the radiator cap, sometimes the pressure cap is on the expansion tank.
If you look inside the pressure cap you should see a spring and sealing washer.

With Radiator system sealed.... all caps on, start ending from cold.... first start of the day.
Start engine and wait till it warms up, you do not need to wait until the engine reaches normal operating temperature... probably safer if you do not.

Switch off engine, the cooling system will be pressurized now. Go to the highest connection point in cooling system.
Sometimes you will find a bleed point there, else loosen a hose or fitting a little bit and flex it open, looking for air or water appearing, if no air/ bubbles tighten up and go to next highest point.

You should complete the bleeding within a few minutes before the system cools and causes a vacuum.

You can even try raising the front or rear of the car..... park it on a big hill!

In some of the old cars this was the only way you could get the heater to work.... the heater core was higher than the top of the engine and would airlock when refilling the system.

apywell · 5th December 2006, 20:29

I have had my 75 for 5 months now and the temp guage rarely stays on the half way mark. It usually resides mid-way between quater and half way. Though recently I have noticed it going as low as about 2mm above the quater mark. Never thought any more of it because the car runs fine.

courier118 · 5th December 2006, 20:49

Ive had my car for 3 yrs and the temperature guage has always sat at a fraction below the halfway mark whatever the conditions.........would be nice to know what others temperature guages sit at

Simon · 5th December 2006, 21:16

Quote:

Originally Posted by courier118

Ive had my car for 3 yrs and the temperature guage has always sat at a fraction below the halfway mark whatever the conditions.........would be nice to know what others temperature guages sit at

For reference, my 5 year old ZT160 has always registered it's temp gauge at half-way. It gets to that temp after only a few minutes, even during the recent frosty spells a few weeks back. It doesn't seem to move about. Not had the chance to test it in very hot weather though as I've only had the car since September this year.

I believe the temperature gauge in modern cars is designed to 'point at halfway-ish' so long as the engine temperature is within a pre-determined range. If it starts to move then it would be because of rather significant temperature changes or because of a fault somewhere (the sensor itself or the electronics that move the needle on the display, for example).

4th December 2006, 22:41	#11
Simon Banned - Join Date: Nov 2006 Location: - Posts: 10,318 Thanks: 0 Thanked 4 Times in 3 Posts	Hi Patch, and welcome to the club! Don't know how long it'll be until some one more important than me gives you an official welcome (you've hidden yourself well in this thread on this area of the forum ), but you can consider yourself welcomed from me!

5th December 2006, 14:41	#13
courier118 Loves to post MG ZT 190+ Join Date: Nov 2006 Location: Newcastle under Lyme Posts: 305 Thanks: 0 Thanked 0 Times in 0 Posts	At last someone with the same problem.........sorry.........I knew the maximum and minimum marks were there but thanks.Ive vacuum filled till im blue in the face............had it running with no cap on to let air draw out.........checked levels last night and today..............sitting bang on the maximum mark..............guage still all over the place between halfway and the next mark down...............i dont know whether theres air in it causing hot spots in the engine.......heater works fine...........whether its the temp sensor,faulty thermostat,faulty guage.When the cars been idling for a while the guage is at the halfway mark and the cooling fan cuts in..............im going to look for my axe soon and chop the damn thing up.......or may just go out and buy that 6.0ltr V8 vauxhall/holden monaro i like

5th December 2006, 16:24	#14
DeeCee Regular poster none Join Date: Nov 2006 Location: none Posts: 93 Thanks: 0 Thanked 0 Times in 0 Posts	What about trying the old fashioned way of bleeding the system. The cooling system runs at pressure to increase the boiling point of the water(antifreeze mixture) The pressure is about 5 to 10PSI, normally controlled by the radiator cap, sometimes the pressure cap is on the expansion tank. If you look inside the pressure cap you should see a spring and sealing washer. With Radiator system sealed.... all caps on, start ending from cold.... first start of the day. Start engine and wait till it warms up, you do not need to wait until the engine reaches normal operating temperature... probably safer if you do not. Switch off engine, the cooling system will be pressurized now. Go to the highest connection point in cooling system. Sometimes you will find a bleed point there, else loosen a hose or fitting a little bit and flex it open, looking for air or water appearing, if no air/ bubbles tighten up and go to next highest point. You should complete the bleeding within a few minutes before the system cools and causes a vacuum. You can even try raising the front or rear of the car..... park it on a big hill! In some of the old cars this was the only way you could get the heater to work.... the heater core was higher than the top of the engine and would airlock when refilling the system.

5th December 2006, 20:29	#15
apywell Gets stuck in Rover 75 Saloon. 2.0 Diesel Auto. Connoisseur SE. Join Date: Nov 2006 Location: Derby Posts: 723 Thanks: 0 Thanked 0 Times in 0 Posts	I have had my 75 for 5 months now and the temp guage rarely stays on the half way mark. It usually resides mid-way between quater and half way. Though recently I have noticed it going as low as about 2mm above the quater mark. Never thought any more of it because the car runs fine.

5th December 2006, 20:49	#16
courier118 Loves to post MG ZT 190+ Join Date: Nov 2006 Location: Newcastle under Lyme Posts: 305 Thanks: 0 Thanked 0 Times in 0 Posts	Ive had my car for 3 yrs and the temperature guage has always sat at a fraction below the halfway mark whatever the conditions.........would be nice to know what others temperature guages sit at