Evening all,
Have done a search on here, but can't find the answer I am looking for.

Until recently, the FF used to warm up fairly quickly, and the temperature gauge never moved from vertical (i.e half way between cold and hot).

It then started occasionally going more towards the cold end of the scale (often when travelling downhill it seemed) before recovering to its normal position.

Now, it hardly ever gets above 1/4 of the way between cold and hot. I am not losing coolant, and don't think there is an air lock - not being familiar with the cooling system, is there a 'waxstat' type thermostat on the AJV8, and if so, could it have stuck open (a common problem on defenders I have run over the years)

If not this, what else should I look for, and where physically will I find it on the car?

Thanks for any help you can offer.  2006 (56 Reg) 4.4 V8 Vogue In Bonatti Grey (Gorgeous!!)

Sorry to resurrect an old post, but did you ever get to the bottom of this?

My 4.2sc (same basic engine) has similar symptoms. 

Had a new thermostat last week...

I get (what I assume is) belt squeal on startup that lasts for about 5 minutes in the mornings.

When I go home at 6PM I don't get the squeal and the car warms up fine. 

I'd get the belt changed and check the belt tensioner is working correctly... It could seize up when cold and then free off when sat in a warm engine bay while your at work and be fine on the way home.... Pete

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2014 L405 Autobiography SDV8 4.4 Loire Blue Ebony interior
2011 L322 Vogue SE 4.4 TDV8 Baltic Blue. Parchment over Navy Interior. Sold
2012 L322 Autobiography 5.0 Supercharged Ipanema Sand, Jet Interior. Sold
2002 L322 Vogue 4.4 V8 Epson Green, Ivory over Aspen Interior (Fatty Offroader) Sold
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When I changed the belt on my 4.2 SC, is also changed the tensioner roller. Same issue although in Nigeria the engine was warming up fine . The tensioner roller bearings seize up over time and that is causing the squeal and belt wear. MY 2010 5.0 SC Galway green and sand interior!!
Have the Faultmate MSV2 Extreme to be tinkering with the settings etc. !!

I believe Ray just changed the thermostat and was ok after, the old one was sticking. If it dont work.......burn it!

If the IId tool cant fix it.......burn the FF.

If the FF cant be fixed......buy a Land Cruiser!

If the LC cant be fixed..............................................BUY a horse !!

What is described is typical of the thermostat sticking open, seems quite common on the jag engines - first thing I did when I got my 4.2 sc. you need to loosen the tensioner to remove the belt to get access so if the squeel has Coe bout after that something isn't right.

What is the cause for the thermostat to be "sticky" or "stick open"?

Asking as I experienced such a scenario about 2 weeks ago in the morning travelling by-roads onto freeway, when it took the temp needle about an hour to start climbing. Ambient temp was pretty cold but that should have not had a impact; correct?

In my instance there was no belt screaming present.

The thermostat is either controlled by wax or sprung metal that when hot opens a valve (normally plunger based) and directs water into the radiator circuit. Over time the spring or wax can tire / break or corrosion can set in reducing the motion or moving parts, or something could get lodged in the valve keeping it open.

In mine the rubber sealing ring around the thermostat valve had broken down lodging the thermostat open.

exactly, the thermostat just wears out basically. They're old and generally reliable tech, but they don't last for ever.

Most Haynes manuals still have the method for bench testing a thermostat, but to be honest they're so cheap these days it's just as easy to fit a new one as soon as you suspect a faulty one.

Thanks guys.

When in doubt, I always replace a thermostat. Not worth the hassle of opening up the housing and then testing it, finding out it is not OK and buying a new one and putting it in. Just easier, buy a new one, drop it in and done. MY 2010 5.0 SC Galway green and sand interior!!
Have the Faultmate MSV2 Extreme to be tinkering with the settings etc. !!