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Discussion Starter #1
Alright. I've just bought a 1990 RRC County, Westminster Grey and all in pretty good condition.

Driving it home the temperature gauge was 3/4 of the way. Owner mentioned this and he drove it that way as a hardware store beater. Sad, I know.

I got home and replaced the thermostat to a 190f from my old RRC parts bin, and both temp sensors. Needle is a little closer to where it is, but still "too hot".

I measured the thermostat housing and it is around ~192f (with an IR gun). So that is puzzling.

When the key is on engine off after a drive, the gauge is directly in the middle. When running it goes to the 3/4 area again. Shut off and it goes to the middle....

I disconnect the sensor at all and it is at 1/4 mark with the key on engine off, engine on it is 1/4 still.

electrical issue? or is my IR gun inaccurate?
 

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Discussion Starter #2
So...I completely disconnected the sensor (on the lower intake manifold, not the one on the thermostat housing) and the bloody thing still says it is overheating..

Did a battery reset and that did nothing.

I can not clear the code 44 CEL, to know if there are any other codes. Wiring to O2 sensor is seemingly intact.
 

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Alright. I've just bought a 1990 RRC County, Westminster Grey and all in pretty good condition.

Driving it home the temperature gauge was 3/4 of the way. Owner mentioned this and he drove it that way as a hardware store beater. Sad, I know.

I got home and replaced the thermostat to a 190f from my old RRC parts bin, and both temp sensors. Needle is a little closer to where it is, but still "too hot".

I measured the thermostat housing and it is around ~192f (with an IR gun). So that is puzzling.

When the key is on engine off after a drive, the gauge is directly in the middle. When running it goes to the 3/4 area again. Shut off and it goes to the middle....

I disconnect the sensor at all and it is at 1/4 mark with the key on engine off, engine on it is 1/4 still.

electrical issue? or is my IR gun inaccurate? Visit this site to know why check engine light on but no codes that you may concern.
I think you need to check if there is leaking coolant somewhere. If the low coolant level can cause overheated when idling.
 

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To clear codes
Rather disconnect battery for a few seconds
Or
Unplug Ecu under passenger seat
Turn key to on
You will a click
Turn off key
Replug the ecu
Then restart the motor
You will get a code 2 or 3
Turn off and restart
It should be cleared
I moved my code reader
Next to the ecu
And left the door off
So I could always see it

This is handy
 

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Discussion Starter #6
Swap the viscous coupling on the fan.
Umm.. why?

I’ve already said it’s not actually overheating. It’s a sensor issue somewhere.


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1970-1995 Range Rover Classic
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Umm.. why?

I’ve already said it’s not actually overheating. It’s a sensor issue somewhere.


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Sorry – I should have read your post thoroughly before posting.

These are simple systems – you have replaced both sensors (only one impacts the gauge), and the t-stat. You could have an issue with the gauge itself or, the instrument cluster (earthing).

I believe RAVE has the resistance range to test the primary temp sensor.

When the VC failed on my 95’ it never overheated – it simply would climb in temp to about 3/4 in the range when the engine was underload.

Hope you get it sorted!
 

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2002-2005 Range Rover MkIV / L405
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Im gonna say faulty gauge, ground to the gauge or wires to the gauge. I would trust a laser temp gauge 10x's over a 30 year old mechanical gauge. At least you know you confirmed you arent overheating so its more of an annoyance at this point.
 

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On my 92 I was replacing stuff and replace the temp sending sensor
The lower one on the intake
Not that anything was wrong with the old one
I just figured it might like a new one
Got it on eBay
Installed it
And it kept reading hot like right to the red line
I put the old one back on and it started
Reading temp like before
Normal
I sent the eBay guy a note and his
Responce was I didn’t have it installed
By a registered Land Rover mechanic
...
I thought “really” what a butt wipe
Anyway
I thought I’d throw that out there
Just cause it’s old and used
It ain’t broke
So the one you are haveing trouble with might be the same as the one I was haveing trouble with
 

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Discussion Starter #10
I'm going to find one from my buddy's parts car and install the sender.

I found out that there is the 3rd sensor, the "sender"
 

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1970-1995 Range Rover Classic
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I've had new temperature senders give an overheat reading before - I'd order two.
To Lear60Man's point, the reading from a laser temperature gauge is going to give the most accurate reading. Short of both sensors and the temp. sender, it's probably just your gauge. With the engine off or at start, the temperature needle should be all the way to the left.
 

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Discussion Starter #12
Haven't had a chance to deal with the truck. I happened to get a new client that I had multiple meetings with that has taken up the past couple days.

Anyway.

The gauge does in fact start all the way to the left, and when warming up the truck basically goes a little over the 1/4 mark with 3-4 minutes of idling.
I don't necessarily trust my laser temp gun, it's Chinese and I'm worried it may be innacurate, though it did read my P38's coolant temperature..which seems to be running hotter than my scan gauge is saying it is. 210-212f idle whereas the gauge says 197-199f.


I have been driving it around with no issues besides the weird rattle, 0-60 is around 14 seconds now so I'm guessing the cats are bad. Still can not get the check engine light to go off, reset does nothing and it comes on instantly first start.

oh. and my low fuel level light goes on at half tank. Kind of appropriate for these trucks but still annoying lol.
 

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Discussion Starter #13
yay. results.

I tested the sender's resistence in the truck today with a Fluke multimeter. Sensor read around 70f cold, and 258f after idling 2 minutes. That's the conversion from ohms(?) unless it's not.

I'm going to order a new part and test it when it comes in before installing.

I believe the test I did is accurate, but I'm not an electrical genius...

My friend with a welder to take the cats out is on vacation for 2 weeks. Tried a shop and was kindly told to get lost. I get it, they don't want to get into trouble :LOL:
 

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Not sure what the history on your RRC is, but the catalytic converters would only be bad if the engine's burning oil or too much blowby is escaping past the piston rings or valves. Bad cats are a symptom of something much more sinister. What's the condition of your spark plugs?

Also, if you're getting a check engine light, what code are you getting?
FYI code-check screen is located under the passenger's seat.
 

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Discussion Starter #15
Plugs are new. Motor is not burning a noticeable amount of oil in my 500 miles of ownership.

as mentioned previously in this thread, which I'll bring forward for your convenience.. Code 44. left o2.

So it may be overfuelling, which may have killed the converter.

But. Doesn't matter. Cats can fail early. My 05 RR's cat failed at 80,000 miles.

This classic has 58k miles.



Don't take me for someone daft simply because of this thread.

I've owned a 1995 LWB 25th Anniversary Edition..of which I saved from a field after sitting 7 years, including servicing the original EAS instead of deleting it.
a 1994 SWB
A 1991 SWB
Another 1991 SWB
A 1984 with 35k miles
and this 1990, with 58,000 miles.
 

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1970-1995 Range Rover Classic
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Don't take me for someone daft simply because of this thread.
Noted. We're all just trying to help, no need for egos to explode.

It could be that your false overheat reading is causing the ECU to overcompensate its air-fuel ratio and give the lambda sensor a rich or lean reading. You could also check the voltage of the oxygen sensor lead wire and rule it out completely (link below, I'm sure you've seen this before)
If your cats are actually ruined though, something caused them to die early; my 1991 has 176,000 miles on it and passed California smog with 15/120 ppm hydrocarbons earlier this year. Mind you it had a warped head and blown gasket for years before I owned it. They don't typically just go bad.
 

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Discussion Starter #17
I have read all of the 14cux threads..
Thanks.


I tested the sensor out of the circuit. As mentioned above. It tested at 258*f after 2 minutes of idling. Tested with a multimeter. This is the sender, not sensor. The EFI sensor tested good, and the fan switch sensor is operating normally.

Who cares why the cats are clogged or rattling. It could have been physical damage from off road. Or it could have been from the bad o2.

If the o2 is fixed, cats are “replaced”, and no faults exist...it’ll be fine.


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Discussion Starter #18
Sorry – I should have read your post thoroughly before posting.



I believe RAVE has the resistance range to test the primary temp sensor.
Don’t worry about it. I’m lazy too hahaha



I did find it and tested it. Thanks man.


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