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Glibbs



Member Since: 18 Aug 2019
Location: West Somerset
Posts: 113
United Kingdom 2006 Range Rover Supercharged 4.2 SC V8 Tonga Green
Engine cools when coasting

4.2 SC
On the third thermostat (the latest LR).
Engine is slow to warm but if the engine is worked it attains and maintains normal temperature but cools right down to almost the blue sector on the gauge when coasting ie descending a hill.
Haven't got much hair left. . . .
TIA Range Rover 4.2 SC
2 Range Rover Classics - one from new but both rusty now.
Rover 3.5 Coupe had since new.
Subaru Legacy 3.0.
BMW K1200RS.
Post #645258 10th Oct 2022 10:34am
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dhallworth



Member Since: 10 Oct 2011
Location: Glasgow
Posts: 3143
United Kingdom 2012 Range Rover Autobiography TDV8 Baltic Blue

Thermostats are a common fail on these. I've had 2 where the seal has deformed and wrapped around the thermostat causing my cars not to get to operating temperatures. 2002 4.6 Vogue SE - Alveston Red with Lightstone Leather
2012 Range Rover 5.0 SC Autobiography in Indus Silver with Jet/Ivory Interior
2012 Range Rover 4.4 TDV8 Autobiography in Baltic Blue with Sand Interior
Post #645260 10th Oct 2022 10:55am
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dingg1



Member Since: 29 Jun 2013
Location: PORTUGAL
Posts: 1348
2007 Range Rover Vogue SE 4.2 SC V8 Stornoway Grey

Viscous fan issue?
Post #645261 10th Oct 2022 11:11am
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Glibbs



Member Since: 18 Aug 2019
Location: West Somerset
Posts: 113
United Kingdom 2006 Range Rover Supercharged 4.2 SC V8 Tonga Green

Afraid not. Range Rover 4.2 SC
2 Range Rover Classics - one from new but both rusty now.
Rover 3.5 Coupe had since new.
Subaru Legacy 3.0.
BMW K1200RS.
Post #645263 10th Oct 2022 11:43am
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maric995



Member Since: 04 Apr 2019
Location: zagreb
Posts: 58
Croatia 2006 Range Rover HSE 4.4 V8 Zambezi Silver

check if your 4.2 engine has second thermostat on the lower coolant hose. Mine 4.4 ajv8 had this problem, and it was this lower thermostat located in the hose RR HSE 4.4 2006 LPG
Post #645410 12th Oct 2022 7:42am
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Glibbs



Member Since: 18 Aug 2019
Location: West Somerset
Posts: 113
United Kingdom 2006 Range Rover Supercharged 4.2 SC V8 Tonga Green

Hi, thanks for your thought. I was told on another forum that it had the other thermostat but after buying a replacement I am now assured by my local garage and Matfords that the SC doesn't have it fitted. . . .
I can't believe though that I have bought three new thermostats from different suppliers in as many weeks which could be faulty! Range Rover 4.2 SC
2 Range Rover Classics - one from new but both rusty now.
Rover 3.5 Coupe had since new.
Subaru Legacy 3.0.
BMW K1200RS.
Post #645428 12th Oct 2022 10:27am
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dingg1



Member Since: 29 Jun 2013
Location: PORTUGAL
Posts: 1348
2007 Range Rover Vogue SE 4.2 SC V8 Stornoway Grey

Neither can I, have you trended the actual temperature on a scan tool? Just to check that the transmitter is working OK..
Post #645431 12th Oct 2022 10:53am
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maric995



Member Since: 04 Apr 2019
Location: zagreb
Posts: 58
Croatia 2006 Range Rover HSE 4.4 V8 Zambezi Silver



If you look closely on this picture, you can see the bottom hose PCH 501310. This is lower thermostat -built in a hose.
If you changed main thermostat, only this could be the reason of your problems RR HSE 4.4 2006 LPG
Post #645432 12th Oct 2022 11:02am
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Glibbs



Member Since: 18 Aug 2019
Location: West Somerset
Posts: 113
United Kingdom 2006 Range Rover Supercharged 4.2 SC V8 Tonga Green

Many thanks.

I've looked it up on Rimmer's site where it states that the part is for both engines!

How can a main dealer get it wrong??

The part should be coming in a day or so - fingers crossed and I'll let you know. . . . Range Rover 4.2 SC
2 Range Rover Classics - one from new but both rusty now.
Rover 3.5 Coupe had since new.
Subaru Legacy 3.0.
BMW K1200RS.
Post #645435 12th Oct 2022 11:23am
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Glibbs



Member Since: 18 Aug 2019
Location: West Somerset
Posts: 113
United Kingdom 2006 Range Rover Supercharged 4.2 SC V8 Tonga Green

It was indeed the 'secondary' thermostat that had failed - all fixed and thanks for your help. Range Rover 4.2 SC
2 Range Rover Classics - one from new but both rusty now.
Rover 3.5 Coupe had since new.
Subaru Legacy 3.0.
BMW K1200RS.
Post #648342 17th Nov 2022 1:40pm
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TorontoDee



Member Since: 27 Sep 2022
Location: Toronto
Posts: 77
Canada 2012 Range Rover Westminster 5.0 SC V8 Santorini Black

Incredible and amazing! 2012 Supercharged L322
Post #648346 17th Nov 2022 3:33pm
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