Does your fuel gauge go up when the engine is revved? I had a similar problem on my Series 3 a long time ago. It was fitted with an amp meter which would shoot up from time to time (when the battery was charging). When it did, the temperature gauge climbed, as did the fuel gauge and the lights were getting brighter. I can't remember if it was the recitifier or voltage regulator in the alternator that was the culprit.
 
Is it not 'part of the experience' running an old vehicle, relying on the technology (in this case instrumentation) of the day. The only additional gauge I would consider would be an oil pressure gauge.

My 2.25d sits a third of the way up the gauge in the cooler months and usually just under half way up in Summer. On hot days it will sometimes nudge just over half way up and whilst I keep an eye on it, it has never crept further.

In the case of the OP, I would remove and check stat (74 degree or 82 degree type??), flush cooling system if not done previously before moving forward.
 
Is it not 'part of the experience' running an old vehicle, relying on the technology (in this case instrumentation) of the day. The only additional gauge I would consider would be an oil pressure gauge.
So you would replace original oil pressure but not temperature?................................... interesting........................
 
I ordered a 74 Degree thermostat as the Land Rover maintenance manual says 74 for 4 Cyl Petrol and Diesel engines, and 82 for 6 Cyl.

The engine was professionally rebuilt back to as-new condition, so the block shouldn't have any sludge in.

I did flush the radiator both ways with a garden hose before I refitted it. All the radiator hoses were also replaced with new ones.
 
I took it out for another run over the weekend and it did the same thing. The dial pointer is right through the centre of the N when it's come up to temperature. When you work the engine hard for a while it rises to the top of the N. It soon drops again when I slow down.
 
Even though you flushed the rad...it could still be part blocked...hand help infra red thermometers are good for finding cool areas on rads.

If it only goes to the top of the N I would not worry as long as your sure the temp ind is correct.
 
So you would replace original oil pressure but not temperature?................................... interesting........................

Nope, I would be adding the oil pressure gauge because it doesn't already have one - not replacing it.

+1 with the infra red thermometer. Very cheap for what they are and seem accurate.
 
Advanced fuel timing will make an engine run a little hotter due to the leaner mix, but wont make a difference on the gauge (tried all sorts adjusting my pump timing and no difference).

If needle sits at bottom of gauge all the time, possibly the feed wire to the voltage regulator has come off (again found that out on mine)

If the sender is breaking down inside and starts earthing, the needle will go right above the H mark. Mines started doing this then it'll come back down to the N and then it'll swing all the way up again. Know its the sender at fault as it does it straight away when key is in the ignition and heater output gets no hotter
 
I have finally got round to looking into this again. I took the vehicle on a run yesterday and the gauge got almost up into the red. I got up to around a constant 50mph over around 13 miles. I thought I would get the engine well warmed through as it hadn't been started in over a month.

The guage went up quite a bit and got almost to the red. I stopped for about an hour and let it cool. I came back a different route over slower roads. the gauge was fine when I wasn't doing speeds above 30.

Am I pushing it too hard trying to do 50 for long periods?

I have ordered a replacement thermostat as that is the easiest thing to swap first.

I am considering fitting this type of digital gauge.

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when I got my s3 I brought it back round the m25 with my foot to the floor - never driven it that hard since but had to get back asap - gauge stayed in the middle
 
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I have finally got round to looking into this again. I took the vehicle on a run yesterday and the gauge got almost up into the red. I got up to around a constant 50mph over around 13 miles. I thought I would get the engine well warmed through as it hadn't been started in over a month.

The guage went up quite a bit and got almost to the red. I stopped for about an hour and let it cool. I came back a different route over slower roads. the gauge was fine when I wasn't doing speeds above 30.

Am I pushing it too hard trying to do 50 for long periods?

I have ordered a replacement thermostat as that is the easiest thing to swap first.

I am considering fitting this type of digital gauge.

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i have a tacho like that, its a autotechnica brand and at night those blue led numbers can be quite bright and dazzling to your eyes, if you get one get one with red led numbers as its less brighter on your eyes at night.

Tony.
 
Does anyone here know the thread size on the standard water temperature sender?

The ones supplied with the aftermarket gauges seem to be 1/8 NPT. I need to know what size of adaptor to buy.
 
I just got one of these. The sender sits under a tie wrapped piece of closed cell foam on the top radiator hose. The red one is good in daylight and not too bright at night. I did have to extend the sender cable.

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Thanks for the reply. Where do you buy those?

I could even fit two. One for the top hose and one for the bottom. Red for the hot feed out of the engine and blue for cold from the radiator.
 
Thanks for the reply. Where do you buy those?

I could even fit two. One for the top hose and one for the bottom. Red for the hot feed out of the engine and blue for cold from the radiator.
Ebay of course. Only a couple of quid each if you wait for shipping from china.
I have 4. Two voltage an amp and a temp.
 
How well would you say they measure the temperature with the probe being on the outside of the hose?
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As for the sender thread I can now answer my own question. It is 5/8-18 UNF.

I removed and replaced the old stat today. It was pretty corroded and also slightly deformed.

There must still be an air lock somewhere, as I stil have 300ml of the coolant I drained out left over. I poured most of it back in.

I will take the vehicle on a proper run tomorrow.
 
It's very accurate at body temp under my tung :p

I put it under a piece of 10mm closed cell foam sheet that is wraped round the hose and zip tied on so its well insulated from atmosphere temp. Not sure how accurate it is but it gives me plenty of warning if it starts going up.
 
Thanks for that, I will look into ordering some.

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Reply aimed at anyone:

I took the vehicle on roughly 30 mile run ealier today.

the gauge did rise into the high side of the "N" segment, but didn't reach the red when moving at full speed. It did however get up to red when I was working my way around some other cars to park up. i stopped it at that point and let it cool down for a few minutes.

The radiator itself seems to be working well. the bottom hose is much cooler than the top.

Could it be something as simple as the temperature sender being the wrong value?
 

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