Thermo confused.

Chris G · 27th October 2016, 22:29

As a continuous worrier I have ran my 1.8T monitoring the temperature in diagnostics for a couple of days now.

I have been informed by forum member TCut that my car should run at a consistent 88 degrees C regardless of time of year or outside ambiant temperature.

In reality the following is happening.

Car at running temp is generally 85 to 87. Put load on the engine it climbs to 89 - 90.. cool air blast following acceleration thus higher speed brings temp back down to 85 / 86 mark.

Suddenly whack the heater on to full ( was cold this morning) it briefly plummeted to 81 before climbing back up to 86 / 87..

Reached destination, left it to tick over.
Fan kicked in at 105.

Personally I see a lot of sense and logic in the above, however I would rather listen to others than assume I know it all.

Does this seem normal or cause for concern?

Ta

Rooney · 27th October 2016, 22:39

It's well within normal expected parameters.

SD1too · 27th October 2016, 23:24

I'd say that you have a problem with your PRT (thermostat) Chris. There should not be that degree of temperature variation in the downward direction, and the 81° which you reported is unacceptable.

Simon

Chris G · 28th October 2016, 07:40

Drive to work this morning pretty much the same thing, I left the heater alone and the lowest figure I've seen once warm was 84.

Temp climbs to 90 when pulling up a hill, crest the hill & go down the other side it drops back to the mid 80s again.

My journey to work is all motorway, will have to see what happens driving around the town.

Car isn't far off due a service soon so will definately raise this as a potential issue.

Thanks.

SD1too · 28th October 2016, 08:18

Chris,

When the engine is cold and as a precaution, check your coolant level in the expansion tank. You may be losing coolant slowly via a leak which is preventing correct pressurisation and leading to these temperature variations.

I'd get this seen to as soon as possible if I were you. Don't wait for a service. It's not worth taking risks with the 1.8 cooling system.

Simon

Chris G · 28th October 2016, 13:28

Quote:

Originally Posted by SD1too

Chris,

When the engine is cold and as a precaution, check your coolant level in the expansion tank. You may be losing coolant slowly via a leak which is preventing correct pressurisation and leading to these temperature variations.

I'd get this seen to as soon as possible if I were you. Don't wait for a service. It's not worth taking risks with the 1.8 cooling system.

Simon

Being well into 1.8 K series ownership mode I check it every other day religiously, no coolant loss to report.
The coolant is clean & free of anything merky.

The oil is also good, a little black as it's done a few miles hence up coming service.

No mayonnaise on the stick or under the cap, engine pulls like a train, car drives lovely.

I was going to get fresh coolant, new stat, water pimp and inlet manifold gasket done as a minimum anyway because I'm taking the car on a very long road trip next year..
So rest assured I'm going to be getting to the bottom of this.

T-Cut · 28th October 2016, 16:33

A replacement PRT is the place to start. Try for the 88C buff OEM type if possible. Unfortunately, most suppliers won't be able to say much about the pressure relief setting, but the colour of the case is supposed to indicate it. The latest thinking from the Lotus fraternity (who seem to know more than most about it) is that the grey version (MGF/TF, Freelander) is now preferred in K16Turbos. This is only 82C opening however and maybe a bit low in yours. Or see the DMGRS shop, not sure what they recommend now, but have stocked 82C buff type.

EDIT: I'm assuming you actually have a PRT rather than the original version. Check there's a wide bore T-Piece in the upper radiator hose.

TC

COLVERT · 29th October 2016, 13:32

There is nothing wrong with the readings you have had in the conditions you have described.

As per g.mc.g's post.

Stop worrying.

kaiser · 29th October 2016, 18:22

The temperature will vary with outside temperature, speed, load and also the use of the heater.

The temperatures you see are fine.

T-Cut · 29th October 2016, 18:49

Quote:

Originally Posted by Chris G

been informed by forum member TCut that my car should run at a consistent 88 degrees C regardless of time of year or outside ambiant temperature.

Mine never, ever runs lower than the thermostat opening point (88C). This applies to typical UK summers and winters alike.

Quote:

Suddenly whack the heater on to full (was cold this morning) it briefly plummeted to 81 before climbing back up to 86 / 87

That may seem normal to some, but I'd be quite concerned if my 1.8T did that.

Quote:

Reached destination, left it to tick over. Fan kicked in at 105.

Near enough. The book says 104°C.

Keep us posted with your ongoing observations.

TC

27th October 2016, 22:29	#1
Chris G Newbie Rover 75 Saloon Join Date: Oct 2016 Location: Worcester Posts: 28 Thanks: 2 Thanked 1 Time in 1 Post	Thermo confused. As a continuous worrier I have ran my 1.8T monitoring the temperature in diagnostics for a couple of days now. I have been informed by forum member TCut that my car should run at a consistent 88 degrees C regardless of time of year or outside ambiant temperature. In reality the following is happening. Car at running temp is generally 85 to 87. Put load on the engine it climbs to 89 - 90.. cool air blast following acceleration thus higher speed brings temp back down to 85 / 86 mark. Suddenly whack the heater on to full ( was cold this morning) it briefly plummeted to 81 before climbing back up to 86 / 87.. Reached destination, left it to tick over. Fan kicked in at 105. Personally I see a lot of sense and logic in the above, however I would rather listen to others than assume I know it all. Does this seem normal or cause for concern? Ta Last edited by Chris G; 27th October 2016 at 22:31.. Reason: Spelling

27th October 2016, 23:24	#3
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: 20,526 Thanks: 1,587 Thanked 3,749 Times in 3,181 Posts	I'd say that you have a problem with your PRT (thermostat) Chris. There should not be that degree of temperature variation in the downward direction, and the 81° which you reported is unacceptable. Simon __________________ "Whatever is rightly done, however humble, is noble." Sir Henry Royce.

28th October 2016, 08:18	#5
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: 20,526 Thanks: 1,587 Thanked 3,749 Times in 3,181 Posts	Chris, When the engine is cold and as a precaution, check your coolant level in the expansion tank. You may be losing coolant slowly via a leak which is preventing correct pressurisation and leading to these temperature variations. I'd get this seen to as soon as possible if I were you. Don't wait for a service. It's not worth taking risks with the 1.8 cooling system. Simon __________________ "Whatever is rightly done, however humble, is noble." Sir Henry Royce.

28th October 2016, 16:33	#7
T-Cut This is my second home Rover75 and Mreg Corsa. Join Date: Nov 2006 Location: Sumweer onat mote o'dust (Sagin) Posts: 21,754 Thanks: 341 Thanked 3,660 Times in 2,924 Posts	A replacement PRT is the place to start. Try for the 88C buff OEM type if possible. Unfortunately, most suppliers won't be able to say much about the pressure relief setting, but the colour of the case is supposed to indicate it. The latest thinking from the Lotus fraternity (who seem to know more than most about it) is that the grey version (MGF/TF, Freelander) is now preferred in K16Turbos. This is only 82C opening however and maybe a bit low in yours. Or see the DMGRS shop, not sure what they recommend now, but have stocked 82C buff type. EDIT: I'm assuming you actually have a PRT rather than the original version. Check there's a wide bore T-Piece in the upper radiator hose. TC Last edited by T-Cut; 28th October 2016 at 16:36..

29th October 2016, 18:22	#9
kaiser This is my second home 75 Tourer 2.5 Auto, 1.8T, 75V8ZT Join Date: Jun 2007 Location: Johannesburg ZA Posts: 6,200 Thanks: 1 Thanked 859 Times in 613 Posts	The temperature will vary with outside temperature, speed, load and also the use of the heater. The temperatures you see are fine. __________________ Worth his V8 in gold

27th October 2016, 22:39	#2
Rooney Suspended MG ZT 135+ Rover 75 CDTi Tourer, 75 2.5 V6 Saloon Join Date: Oct 2014 Location: County Antrim Posts: 2,027 Thanks: 835 Thanked 882 Times in 557 Posts	It's well within normal expected parameters.

28th October 2016, 07:40	#4
Chris G Newbie Rover 75 Saloon Join Date: Oct 2016 Location: Worcester Posts: 28 Thanks: 2 Thanked 1 Time in 1 Post	Drive to work this morning pretty much the same thing, I left the heater alone and the lowest figure I've seen once warm was 84. Temp climbs to 90 when pulling up a hill, crest the hill & go down the other side it drops back to the mid 80s again. My journey to work is all motorway, will have to see what happens driving around the town. Car isn't far off due a service soon so will definately raise this as a potential issue. Thanks.

29th October 2016, 13:32	#8
COLVERT This is my second home R75 Saloon. Join Date: Feb 2009 Location: France/or Devon. Posts: 14,003 Thanks: 3,851 Thanked 2,167 Times in 1,816 Posts	There is nothing wrong with the readings you have had in the conditions you have described. As per g.mc.g's post. Stop worrying.