Go Back   The 75 and ZT Owners Club Forums > The 75 and ZT Owners Club Forums > Technical Help Forum
Register FAQ Image Gallery Members List Calendar Mark Forums Read
Notices

Reply
 
Thread Tools Display Modes
Old 31st May 2019, 13:59   #1
Raymie75
Newbie
 
75 tourer

Join Date: May 2019
Location: Greenock
Posts: 14
Thanks: 4
Thanked 1 Time in 1 Post
Default Rad fan running constantly, 75 club se ctdi

Sorry if this is a repeat post, but i cant find a post relating to the problem. I have an issue with the radiator fan running constantly, this causes the temp guage to barely lift from cold. Any ideas on a fix for this? Fan sender possibly? Thanks
Raymie75 is offline   Reply With Quote
Old 2nd June 2019, 20:57   #2
wnj516
Avid contributor
 
ZT400 SE

Join Date: Jan 2007
Location: Llanelli, S Wales
Posts: 155
Thanks: 7
Thanked 15 Times in 15 Posts
Default

I would say the fan control relay in it's control box attached to the fan cowling is stuck closed, try tapping the box if possible as a temp measure. Needs a new relay get an uprated one either 40 or 60 amp, to change bumper has to come off to get the fan/cowling off or at least on mine.
wnj516 is offline   Reply With Quote
Old 3rd June 2019, 07:33   #3
SD1too
Doesn't do things by halves
 
SD1too's Avatar
 
Rover 75 2.5 Connoisseur Auto (1999) Dealer launch model.

Join Date: Mar 2007
Location: Former Middlesex
Posts: 20,265
Thanks: 1,587
Thanked 3,749 Times in 3,181 Posts
Default

Quote:
Originally Posted by Raymie75 View Post
I have an issue with the radiator fan running constantly ....Any ideas on a fix for this?
Hi Raymie,

This is well known problem with the diesel engine. I'm afraid that the cause is a failed PWM controller in the fan control box. This is the electronic printed circuit board which drives the relays. These are not available as a spare part unless club members Arctic or Jules happen to have a second-hand one. However, another club member with electronics expertise, FrenchMike, offers a repair service if you post it to him in France.

If none of those options is possible then it's a new fan and control box assembly I'm afraid.

Simon
__________________
"Whatever is rightly done, however humble, is noble."
Sir Henry Royce.
SD1too is offline   Reply With Quote
Old 3rd June 2019, 07:44   #4
marinabrian
 
marinabrian's Avatar
 
MG ZT

Join Date: Jan 2011
Location: Newcastle Upon Tyne
Posts: 20,151
Thanks: 3,565
Thanked 10,837 Times in 5,718 Posts
Default

Quote:
Originally Posted by Raymie75 View Post
Sorry if this is a repeat post, but i cant find a post relating to the problem. I have an issue with the radiator fan running constantly, this causes the temp guage to barely lift from cold. Any ideas on a fix for this? Fan sender possibly? Thanks
You need to activate the on board diagnostics to see what the ECM is seeing the engine temperature as.

If the coolant temperature sensor (CTS) is defective or the wiring to it, then the ECM sees the temperature as -130 degrees Celcius, and the coolant fan operates continuously.

The OBdiagnostic how too HERE

It's a quick enough test to carry out

Brian
marinabrian is offline   Reply With Quote
Old 3rd June 2019, 08:05   #5
TeeCee
Avid contributor
 
TeeCee's Avatar
 
Rover 75 Saloon

Join Date: Aug 2013
Location: Ruislip
Posts: 107
Thanks: 2
Thanked 30 Times in 19 Posts
Default

Er, it should?
Mine runs all the time at low speed while the airco is on (now the warm weather's here) and I thought they all did that. Turn the climate control off and it should stop.

The engine not warming up won't be the fan, it'll be that the thermostat has cashed its chips. The fan has no additional cooling effect until the thermostat opens and coolant circulates through the rad. CDT / CDTi thermostats are notoriously unreliable. Do what everyone else (including myself) does and fit a secondary one in the top hose.
__________________
Objects in the rearview mirror may be enormous and a very long way away.
TeeCee is offline   Reply With Quote
Old 3rd June 2019, 09:33   #6
SD1too
Doesn't do things by halves
 
SD1too's Avatar
 
Rover 75 2.5 Connoisseur Auto (1999) Dealer launch model.

Join Date: Mar 2007
Location: Former Middlesex
Posts: 20,265
Thanks: 1,587
Thanked 3,749 Times in 3,181 Posts
Default

Quote:
Originally Posted by TeeCee View Post
Er, it should?
Mine runs all the time at low speed while the airco is on ... Turn the climate control off and it should stop.
Tim raises something which isn't clear from your original post Raymie. Ensure that you have 'Econ' selected on the air con./heater control panel. Does the radiator fan stop now? Or does it continue to run even when you've removed the ignition key, centrally locked the car and left it for several minutes, even with a cold engine?

Simon
__________________
"Whatever is rightly done, however humble, is noble."
Sir Henry Royce.
SD1too is offline   Reply With Quote
Old 3rd June 2019, 09:38   #7
Raymie75
Newbie
 
75 tourer

Join Date: May 2019
Location: Greenock
Posts: 14
Thanks: 4
Thanked 1 Time in 1 Post
Default

Hi. I have the heater switched off most of the time, does this mean the ac is off too? Is it worth checking any senders first?
Raymie75 is offline   Reply With Quote
Old 3rd June 2019, 09:41   #8
SD1too
Doesn't do things by halves
 
SD1too's Avatar
 
Rover 75 2.5 Connoisseur Auto (1999) Dealer launch model.

Join Date: Mar 2007
Location: Former Middlesex
Posts: 20,265
Thanks: 1,587
Thanked 3,749 Times in 3,181 Posts
Default

Quote:
Originally Posted by Raymie75 View Post
Hi. I have the heater switched off most of the time, does this mean the ac is off too?
Yes.

Does the radiator fan continue to run when you've removed the key, locked the car and left it for ten minutes? If so, I doubt that you need to check any senders.

Simon
__________________
"Whatever is rightly done, however humble, is noble."
Sir Henry Royce.
SD1too is offline   Reply With Quote
Old 3rd June 2019, 09:51   #9
Mike Trident
Posted a thing or two
 
Mike Trident's Avatar
 
Rover 75 CDTi Saloon & Citroen C1

Join Date: Jun 2016
Location: Oakenshaw, Near Bradford
Posts: 1,618
Thanks: 385
Thanked 552 Times in 328 Posts
Default

Check what Brian says, he knows his stuff.

Normally the temp gauge not moving is a thermostat problem. However, if you have a faulty sensor who knows what the engine temp really is, the gauge can only show what it's been told.
__________________
Rover 75 2.0 CDTi (131Ps) Conn SE Saloon. (Manual)
160 Remap, cruise control, electric window blind, temp gauge, Real walnut / ZT interior, FBH with GSM control.

BORN
Tuesday, 5th October 2004 @ 12:35:52
This vehicle was the 104,679th 75 to run off the production line, out of 112,381
This vehicle was the 3,318th 75 CDT Connoisseur SE (135) to be made out of 4,744
This vehicle was the 12,440th 75 in Starlight Silver (code: MBB) to be made out of 14,280 Starlight Silver 75s
Mike Trident is offline   Reply With Quote
Old 3rd June 2019, 12:33   #10
Raymie75
Newbie
 
75 tourer

Join Date: May 2019
Location: Greenock
Posts: 14
Thanks: 4
Thanked 1 Time in 1 Post
Default

The fan stops spinning as soon as ignition is turned off. As sensors ar cheap, surely its worth changing? I will be taking the inlet manifold off soon to clean it, where are/is the sender(s) located?
Raymie75 is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT. The time now is 19:01.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Copyright © 2006-2023, The Rover 75 & MG ZT Owners Club Ltd