Replacing temp sensor ZT190

paulcnb · 4th February 2014, 21:15

Hi,
I haven't been able to find an answer by seaching this site so will ask my question here. Am awaiting delivery of a new temp sensor and in the meantime would appreciate some advice re fitting it. My workshop manual is the multi-engine type of document and (for me) is not that clear nor easy to follow.

My queries are: is the temp sensor visible and/or accessible once I remove the plastic shroud from the top of the V6 motor?
Assuming some coolant will be lost between removing the old sensor and screwing in the new one, can I just top up the expansion tank - or do I need to follow an established refill/bleed procedure?

Your advice would be much appreciated.

Regards,
Paul
2002 ZT190 V6

SD1too · 4th February 2014, 21:23

Quote:

Originally Posted by paulcnb

... is the temp sensor visible and/or accessible once I remove the plastic shroud from the top of the V6 motor?

It's just about visible provided you know what you're looking for, but you'll need to do some further dismantling to gain access.

Quote:

Assuming some coolant will be lost between removing the old sensor and screwing in the new one, can I just top up the expansion tank - or do I need to follow an established refill/bleed procedure?

If you partially drain the cooling system it would be sensible to follow the bleeding procedure when refilling.

Why are you doing this Paul? The coolant temperature sensor isn't known for being faulty.

Simon

Wayne B · 4th February 2014, 23:10

I had mine done by a mechanic a couple of years ago & he got to it by removing the air filter housing & came in from the side using a socket & knuckle. Didn't take him long & he did bleed the system afterwards.

Wayne.

paulcnb · 5th February 2014, 22:30

Thanks fellas. Clearly the sensor is not easily spotted or accessed and the car will need re-bleeding after changing it - so I will leave it to my mechanic friend to do after he has settled in to his new home.

Simon - you asked why the sensor. My temp gauge is intermittently dropping to zero for no apparent reason. After stopping and switching the ignition off and on, the gauge will eventually resume normal operation, but for how long is anyone's guess. Following how to advice from the another Rover forum, I turned on the OBD so that it will show real-time engine temp. The last time it occurred, the gauge dropped from normal to zero, while the OBD dropped from 90C to around 10C in about 4 or 5 seconds. As it seems impossible for water to go from 90C to 0C in the middle of an australian summer, I think is is fairly safe to assume the temp sensor is U/S or is making and breaking contact. For information, the car has never actually overhated and actual engine temp under the bonnet seems perfectly normal.

Regards,
Paul
2002 ZT190

SD1too · 5th February 2014, 23:41

Thanks for the explanation Paul. The loom from the coolant temperature sensor enters a connector just beside the throttle body. It might be worth checking that first.

Simon

mh007 · 6th February 2014, 07:17

If your mechanic decides to remove the inlet manifold to gain access, it may be worth replacing the thermostat (in kit form - hoses/clips/thermostat) if it hasn't been replaced recently.

Just an idea but another common failure (thermostat housing leaks)

paulcnb · 6th February 2014, 09:27

Thank you for the tip Simon - I will check the loom near the throttle body to-morrow morning. With any luck it may be that I have inadvertently disturbed the loom during engine cleaning.

For MH007 (sorry, didn't get your name)- The timing belt/tensioner/thermostat/water pump/antifreeze and plugs were all replaced around 1500Ks ago (and it cost a small fortune). This problem with the temp gauge only started recently so I assume it is not related to the refurbishment work which was undertaken several months ago.

Regards,
Paul
2002 ZT190

4th February 2014, 21:15	#1
paulcnb Newbie MG ZT 190+ Join Date: Feb 2013 Location: Canberra Posts: 19 Thanks: 3 Thanked 3 Times in 3 Posts	Replacing temp sensor ZT190 Hi, I haven't been able to find an answer by seaching this site so will ask my question here. Am awaiting delivery of a new temp sensor and in the meantime would appreciate some advice re fitting it. My workshop manual is the multi-engine type of document and (for me) is not that clear nor easy to follow. My queries are: is the temp sensor visible and/or accessible once I remove the plastic shroud from the top of the V6 motor? Assuming some coolant will be lost between removing the old sensor and screwing in the new one, can I just top up the expansion tank - or do I need to follow an established refill/bleed procedure? Your advice would be much appreciated. Regards, Paul 2002 ZT190 V6

5th February 2014, 23:41	#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: 20,382 Thanks: 1,587 Thanked 3,749 Times in 3,181 Posts	Thanks for the explanation Paul. The loom from the coolant temperature sensor enters a connector just beside the throttle body. It might be worth checking that first. Simon __________________ "Whatever is rightly done, however humble, is noble." Sir Henry Royce.

4th February 2014, 23:10	#3
Wayne B Loves to post MGZT Join Date: Oct 2011 Location: Havant Posts: 312 Thanks: 10 Thanked 2 Times in 2 Posts	I had mine done by a mechanic a couple of years ago & he got to it by removing the air filter housing & came in from the side using a socket & knuckle. Didn't take him long & he did bleed the system afterwards. Wayne.

5th February 2014, 22:30	#4
paulcnb Newbie MG ZT 190+ Join Date: Feb 2013 Location: Canberra Posts: 19 Thanks: 3 Thanked 3 Times in 3 Posts	Thanks fellas. Clearly the sensor is not easily spotted or accessed and the car will need re-bleeding after changing it - so I will leave it to my mechanic friend to do after he has settled in to his new home. Simon - you asked why the sensor. My temp gauge is intermittently dropping to zero for no apparent reason. After stopping and switching the ignition off and on, the gauge will eventually resume normal operation, but for how long is anyone's guess. Following how to advice from the another Rover forum, I turned on the OBD so that it will show real-time engine temp. The last time it occurred, the gauge dropped from normal to zero, while the OBD dropped from 90C to around 10C in about 4 or 5 seconds. As it seems impossible for water to go from 90C to 0C in the middle of an australian summer, I think is is fairly safe to assume the temp sensor is U/S or is making and breaking contact. For information, the car has never actually overhated and actual engine temp under the bonnet seems perfectly normal. Regards, Paul 2002 ZT190

6th February 2014, 07:17	#6
mh007 This is my second home MG ZT260 SE, MG ZT190+, MG ZTT 160, R75 Conn SE 2.0, R75 Conn SE 2.5 X 3, R75 Club SE 1.8, P5B Coupe Join Date: Jul 2009 Location: Keynsham, Bristol Posts: 4,211 Thanks: 65 Thanked 635 Times in 499 Posts	If your mechanic decides to remove the inlet manifold to gain access, it may be worth replacing the thermostat (in kit form - hoses/clips/thermostat) if it hasn't been replaced recently. Just an idea but another common failure (thermostat housing leaks)

6th February 2014, 09:27	#7
paulcnb Newbie MG ZT 190+ Join Date: Feb 2013 Location: Canberra Posts: 19 Thanks: 3 Thanked 3 Times in 3 Posts	Thank you for the tip Simon - I will check the loom near the throttle body to-morrow morning. With any luck it may be that I have inadvertently disturbed the loom during engine cleaning. For MH007 (sorry, didn't get your name)- The timing belt/tensioner/thermostat/water pump/antifreeze and plugs were all replaced around 1500Ks ago (and it cost a small fortune). This problem with the temp gauge only started recently so I assume it is not related to the refurbishment work which was undertaken several months ago. Regards, Paul 2002 ZT190