4.6 Range Rover

89foxgt · Post by **89foxgt** » Mon Apr 06, 2015 4:48 pm

Hi Guys,just bought a 4.0 se Range Rover fitted with a 4.6 that has the dreaded overheating problem,ive basically ignored what the previous owner told me as had conflicting stories so started from scratch,ive bypassed the heater to rule that out,drained and refilled system and added a Steel seal to the system and started up,after about 1/2 hr idleing the temp started to creep up to the red.All coolant hoses were hot but found the top of rad hot but the rest of rad cold so suspected thermostat.Then I spotted it a monstrosity of a plastic thermostat fitted to the bottom hose(as fitted to Freelanders).Im thinking of binning this and converting back to the old style as on the 3.9 and the TVR engines as these don't tend to be as problematic also gona change the rad.

Hasa anyone done this conversion??? Cheers Stu

ChrisJC · Post by **ChrisJC** » Mon Apr 06, 2015 7:59 pm

Why not just fit a new thermostat?

The cooling system is entirely different - the 'stat has a bunch of hoses going into it.

Chris.

89foxgt · Post by **89foxgt** » Mon Apr 06, 2015 11:44 pm

ChrisJC wrote:Why not just fit a new thermostat?

The cooling system is entirely different - the 'stat has a bunch of hoses going into it.

Chris.

yes i know they are diffetent but the older system tends to have less problems,ive had disco v8 and rrc v8 and never had any overheating probs,i can always convert it back if it doesnt pan out,but cant see why it wont work,tvr's have the older system and very rarely have probs and they have 4.0,4.2 and 5.0 variants as you probably know. Stu

DaveEFI · Post by **DaveEFI** » Tue Apr 07, 2015 8:43 am

Anyone know just why they changed the thermostat position after all those years of it being in the 'normal' position?

89foxgt · Post by **89foxgt** » Tue Apr 07, 2015 12:41 pm

Yeh my thoughts exactly,i have a m8 who breaks Discos and RRs he has the parts i need. Stu

ChrisJC · Post by **ChrisJC** » Tue Apr 07, 2015 5:53 pm

Let us know how you get on.

Chris.

DEVONMAN · Post by **DEVONMAN** » Wed Apr 08, 2015 8:02 am

DaveEFI wrote:Anyone know just why they changed the thermostat position after all those years of it being in the 'normal' position?

The thermostat position and type was changed in line with the modern practice of closing off the bypass system once the thermostat has opened. This then put all the hot coolant through the rad and the engine temp then is more controllable. But did it work for the RV8

89foxgt · Post by **89foxgt** » Thu Apr 09, 2015 6:43 pm

DEVONMAN wrote:
DaveEFI wrote:Anyone know just why they changed the thermostat position after all those years of it being in the 'normal' position?
The thermostat position and type was changed in line with the modern practice of closing off the bypass system once the thermostat has opened. This then put all the hot coolant through the rad and the engine temp then is more controllable. But did it work for the RV8

It seems to me that only RR P38 4.0 and 4.6 have loads of problems with overheating where as the other variants in other vehicles less so.

Anyway my 4.6 is goosed,suspected liners,my m8 has a 75,000 mile 4.0 I can have,ive also spoken to another m8 who is an Independent TVR speacialist who has a few bits lying around,so basically my cooling system will be based around the TVR 4.0L,need to save some cash up 1st Cheers Stu

ChrisJC · Post by **ChrisJC** » Thu Apr 09, 2015 8:52 pm

The 4.0 and 4.6 don't have problems with overheating. They have problems with the blocks cracking, and water getting low. When there isn't enough water in the engine, they overheat. Moving the thermostat won't change that!

When there is enough water in the engine, the cooling system is more than adequate. It's fine in the southern US, so the relative cold in the UK is absolutely no problem at all!

Chris.