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1970-1995 Range Rover Classic
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Discussion Starter #1
Can some one direct me to how the aux fan works or where to locate the ground for the temp gauge every time I come in to town the gauge goes to red light comes on I give it a little throttle and it goes back to normal rads new btw and my heater only works on manual control auto has left the box
I thinks it electrical grounds if I could wire the ac fan to a switch that would be nice too I only drive it in winter so don’t need ac
 

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What year and model? You have posted in the P38 section but have a Classic pictured.

If it is a P38 you will be better off figuring out why your are overheating instead of wanting to mask it with a manual condenser fan switch. The fans on a P38 are not for engine cooling they are for the climate control system to draw more air through the condenser, thus why they are called condenser fans. Wiring diagrams and pinouts are in RAVE.
 

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1970-1995 Range Rover Classic
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Discussion Starter #3
It’s a 98 4.0 I own 2 classics hence the pic! Classics are getting hard to find so the p38s the winter beater like the truck but not the electrical I’m not familiar with the rave manual thought some one might have had a similar issue not looking to replace every part just keep it running till spring
 

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Okay... the fans still have nothing to do with engine temp though. Either your radiator is clogged up or your water pump is getting weak. If higher RPMs drops the temp I would vote for a rotted water pump impeller. The higher RPMs increases the water flow. Do you have good heat in the cabin?
 

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1970-1995 Range Rover Classic
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Discussion Starter #5
Heats really great I thought I may have an air lock but I have continuous heat without any cold spots so that kinda rules that out when it starts to act up heaters gets super hot rads new thermostat??
 

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1970-1995 Range Rover Classic
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Discussion Starter #6
Viscous is working btw if I was to do pump and stat which do you recommend can I use a britpart on it or is that asking for failure??
 

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Britpart is some thing of a crap shoot. If you have NAPA up there you can pick up their Altrom brand NEW for the price or reman OE. Oreilly's has Import Direct NEW and no longer handle any reman. I really have no clue what retail chains you have up there. Down here most of the chains offer life time warranty on their new and reman pumps, alternators etc.
 

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Just remembered you have carquest up there. They have new direct fit water pumps with lifetime warranty for about $180US. Down here they also carry Airtex reman for about $150US with a one year warranty.
 

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1995-2002 Range Rover P38A
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417 Posts
Make sure to check your viscous fan connector to make sure it is true while spinning. I agree water pump and thermostat in order. I would do thermo first and try it. I had 2 pumps go out because my viscous fan connector was warped.
 

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1995-2002 Range Rover P38A
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107 Posts
I would just like to add something I recently experienced in my work where the water pump on the engine most likely is turning bad.
This was diagnosed because the machine in question had no heat in the cabin.
Checked the heater core. Not clogged.
Checked the heater valve. Not perfect condition, but ruled it out by replacing it with a full flow adapter.
Almost no coolant is pumped through the heater core at idle, some coolant is pumped at high idle. Heater core gets warm to the touch, but the blowers cool it down immediately.
The engine does not overheat though, yet!


So if the original poster has excellent heat in the car. Wouldn't that at least indicate the coolant is circulated correctly?
I'd check that the thermostat is opening and check that the radiator get's uniformly hot and wether the viscous coupling on the fan locks up correctly as previously said.
 

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Kretslopp, please put your Rover's year and model in your signature as noted in the site guidelines. There is no heater valve in a petrol P38. The heater core is full flow at all times just as the A/C evaporator is full flow when the compressor is running. Temperature is controlled by the blend motors, not reducing core flow.
 

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So if the original poster has excellent heat in the car. Wouldn't that at least indicate the coolant is circulated correctly?
Correct circulation has nothing to do with enough flow. Reduced flow at low RPMS means less coolant flow and less cooling and slow speeds mean less air through the radiator. With added air flow on the freeway and higher RPMs circulating coolant faster he is not over heating.

Cheap aftermarket replacement water pumps have been known for years to have impellers that corrode quickly. Genuine pumps will do so as well if folks don;t have proper coolant ratio. When the impellers start to rot, come loose or break as the plastic ones occasionally do, you have drop in flow. Think of it as a propeller on a boat. You have three nice new blades providing 100% trust matching the RPM. Slower RPM mean slower means slower speed. Now take a corroded propeller that half the surface area has rotted away and you are not going to get 100% thrust. Lets say you get 50% thrust. You are still moving but you are only moving at 50%.
 

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1970-1995 Range Rover Classic
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Discussion Starter #13
The fan is blowing pretty good but a new viscous isn’t that much if I’m doing the pump I should just replace it I had a issue with the defender last year where the viscous only worked half way? And the truck would heat up but not cool down so don’t think that’s the issue here since she comes back down to perfect after a throttle up to 2000 rpm thanx for the help can’t order parts till the 2nd but now know,thermostat,pump and the fan just because I’m in there
 

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1995-2002 Range Rover P38A
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Kretslopp, please put your Rover's year and model in your signature as noted in the site guidelines.
Ok, done.

There is no heater valve in a petrol P38. The heater core is full flow at all times just as the A/C evaporator is full flow when the compressor is running. Temperature is controlled by the blend motors, not reducing core flow.
Yes I know. There is no valve on the diesel model either. I was just referring to a fault finding process I've done on a different vehicle.
I read all the comments more thoroughly and you're probably right about the water pump or radiator.

I've never had a faulty water pump myself but I had a car once with a thermostat that stayed shut and that one more or less overheated constantly, the same thing with a van my father had. Constant overheating. Vehicle speed didn't matter in both those cases.
 

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One thing I found recently with my P38 was that transmission radiator which sits in front of the main radiator was clogged up with dead flies etc., and was blocking a lot of the air flow to the engine cooling circuit. Once this was replaced all my overheating issues disappeared.
 

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If the heater is working very well but it is getting hot at idle that suggests poor flow through the radiator. The heater matrix is acting as the radiator but isn't capable of dissipating all the heat. Water pump or clogged radiator would be where my money goes.
 

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In my experience, the OEM pump is good for 110-120k miles and crappy Britpart stamped impeller versions about 10k. Easy to spot them, the impeller is basically a folded piece of sheet metal while the OEM is a cast piece of bronze. With the price of radiators and water pumps being cheap now, I would be tempted to replace both if you know they haven't been done.
 

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1970-1995 Range Rover Classic
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Discussion Starter #18
Just wanted to follow up on this I found a really good deal on another p38 so I thought I would just let this one cook to see what would happen guess what,
she never overheated at all! the po had put in newer km/h cluster in which causes a few other electrical issues so I put the old mp/h cluster in it and the gauge sits rock steady at just a shade under half and slides up to half in the city so if anyone else has this problem check your gauge first!
 

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1995-2002 Range Rover P38A
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Ha, nice!

I had a similar experience a while ago when I wanted to check my how hot my engine got. Temp gauge reached 11 o clock.

We have a new Infrared thermometer at work I used to check the engine temp. I got concerned when it showed over 100°C on the cylinder head. Radiator showed nearly 100°C also. Oil pan was around 120°C.
Hmm, that can't be right, I thought, so I started checking the whole system and good thing because I found out the radiator had a duff baffle on top (diesel model).
Later I bought an external temp gauge and sensor and a 38mm sensor housing and put it in the upper radiator hose to finally check what temp I got.

At first I thought the sensor was broken when it showed 50°C as soon as ignition was turned on. And when engine was running the temp stopped at 90°C. I still thought the sensor or gauge was malfunctioning when at the same time the IR thermometer showed 110°C.

Then it slowly dawned on me while looking at the IR thermometer. "It's you, you little rascal that's not working. Showing 20°C too much @ 90°C ."


There never was an overheat problem. Aside from the radiator that I fixed.
 
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