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Range Rover P38 Overheating. A/C Fans Override.

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#21 ·
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#22 ·
Dave, I thought that 300TDI VC is only for diesels:unsure:
 
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#23 ·
Good point Kapila. It definitely fits the diesel, that I know. Not sure if the central viscous clutch mechanism is the same petrol/diesel. I assumed it was.
 
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Discussion starter · #24 · (Edited)
Is the fan clutch on the 1997 GEMS have reverse or normal thread?

Just saw a YouTube video where the Thor has normal thread, counterclockwise to remove.

Another question: When putting the cabin temp to LOW and turning the AC on (light off), the electric fans do not turn on - when I ground them they work - any idea how to diagnose the issue?

Sent from my MAR-LX1M using Tapatalk
View attachment 310640 View attachment 310641
 
#27 ·
P38HSE46 said:
Is the fan clutch on the 1997 GEMS have reverse or normal thread?

Just saw a YouTube video where the Thor has normal thread, counterclockwise to remove.

Another question: When putting the cabin temp to LOW and turning the AC on (light off), the electric fans do not turn on - when I ground them they work - any idea how to diagnose the issue?

Sent from my MAR-LX1M using Tapatalk
View attachment 310640 View attachment 310641
Click to expand...
I think you will find they depend on both engine temp and AC pressure.

They have three modes i.e. Off / On Slow (fan in series / On Fast (fans in parallel)
 
#28 ·
P38HSE46 said:
Is the fan clutch on the 1997 GEMS have reverse or normal thread?

Just saw a YouTube video where the Thor has normal thread, counterclockwise to remove.

Another question: When putting the cabin temp to LOW and turning the AC on (light off), the electric fans do not turn on - when I ground them they work - any idea how to diagnose the issue?

Sent from my MAR-LX1M using Tapatalk
View attachment 310640 View attachment 310641
Click to expand...
Thor has normal thread
Just changed mine for a Hayden Automotive 2781 which was recommended to me by a D2 owner. Intermediate between normal and heavy duty.
The electric fans do not always come on when using the AC. Don't think mine have ever come on. I suspect they would if driving slowly on a hot day.
 
#29 ·
The fans are controlled by the AC pressure switch in the high side pipework. Normal operating pressure of R134a at 20C ambient, is 2.6 bar (38psi) on the low side and 10.3 bar (150 psi) on the high side. Pressure on the high side will increase above this if the ambient is higher or if it is having to work hard. The pressure switch operates when the pressure reaches 21 bar (305 psi), brings in relays 13 and 14 so the fans run at high speed in parallel. The switch remains operated until the pressure drops to below 17 bar (247 psi).

The fans should run in series, so at low speed, whenever the AC Control relay (relay 18) is operated by the engine ECU when it supplies the AC grant to the HEVAC.

If they have never come on, not even at slow speed when the AC is operating, the most likely cause is one of the fans being faulty, either seized or more likely open circuit.
 
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Discussion starter · #30 ·
UPDATE: Fan clutch removed and replaced with a new one, still overheats.

The radiator was removed and has very good flow.

Another thing, the temperature is erratic, sometimes it overheats, other times it doesn't.

I am starting to think it may be a failed thermostat, which is also new.

Any recommendations on by passing it as a test?

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#31 ·
Our Thor Rovers have a way overkill cooling system for normal driving. When you feel you reach 190 degrees does the top hose get a solid feel when thermo opens. If it is solid before mabey head gaskets leaking air into system but that would be instant at start. You could of got a bad thermo or water pump but lets start with basics.
 
#36 ·
Fitting no name parts in something as critical as the cooling system is asking for trouble. For something that could potentially destroy your engine, at the price I'd go for genuine Thermostat - Complete - V8 | Range Rover P38

But with it varying, it does sound like you have air in there. If you squeeze the top hose, can you hear gurgling in the cooling system? If you can, that's air.
 
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#37 ·
I always fill the top hose first with antifreeze then when it gets almost to the top I finish filling with distilled water.
Then fill radiator with a funnel. Connect hose you may get a little water spillage. Then straight anti freeze into the coolant tank until that is to the mark. Never had to burp or anything, heater works right away. Adjust your ratio to get 50/50 mix.
 
Discussion starter · #38 ·
Richard_G said:
Fitting no name parts in something as critical as the cooling system is asking for trouble. For something that could potentially destroy your engine, at the price I'd go for genuine Thermostat - Complete - V8 | Range Rover P38

But with it varying, it does sound like you have air in there. If you squeeze the top hose, can you hear gurgling in the cooling system? If you can, that's air.
Click to expand...
From the link you gave me, only Britpart and Bearmatch are available. Are they both that bad?

How can I have the thermostat bypassed?

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#39 ·
Who knows and that is the problem. If you buy an aftermarket part you have no way of knowing whether it is made to the original spec or not. Due to the multiple pipes and the fact that the location of them is important, it isn't easy to bypass it. You could drill a few holes in the plate if you really must, or just pour boiling water out of a kettle into it and confirm it opens. If it does, then that isn't the problem.
 
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DaGlitch
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