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Switchable temperature gauge


p.mole1

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I have fitted a temperature gauge sender into my oil filter housing so I can switch between oil and water temperature using the same gauge on the dashboard. I intend to use this on track days to see if I require an oil cooler.

It is a 1995 K series Caterham with VDO gauges. I bought a VDO sender but it under reads by a huge margin. Both senders have the same resistance cold.

Does anyone know what sender I should be using, the water sensor looks like a standard Rover item. I am assuming the sensor I have in the oil filter housing has the wrong resistance once it starts to warm up

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I did this on my old x/flow that had VDO senders and gauges. Basically I used the same sender for the oil as for the water. From memory there are 2 different senders one has a temp range upto 120 deg the other 150 deg. If you use the wrong one for the gauge then the gauge won't give the right reading. 

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The 1/8npt brass threaded water sender from Caterham parts should do the job, water temp gauge will read up to about 120c which should be enough

i thought the standard track upgrade for a K series was the apollo de-ariating tank? This increased the oil capacity by 2L and provided a more reliable source of oil for the pump. These had a temp sender in them for monitoring the oil temp and i think they provided some cooling capabilities, probably through increasing the oil capacity. Not an expensive upgrade

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Thanks, I am sure it is under reading as the sump was very hot to the touch, not very scientific but it was hotter than the 40 degrees the gauge was showing.

I have an oil filter sandwich plate for an Accusump and it is fitted to that via a 1/2 bsp 1/8 ntp adaptor. I can't find a part number on the original sensor but it looks like an OE Rover part with two pins only one of which is used.  I am assuming the sensors are thermistors as the resistance seems to get lower with temperature. 

The Caterham sensor seems to be for cars from 1996, the sensor I bought was for a VDO gauge but it must be the wrong resistance I will have to try them both in boiling water

 

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Are you sure you are looking at the right sensors? There are normally two temperature sensors, one with a moulded plastic plug with two pins and one with a single spade or similar terminal on the top. The two pin sensor is the Rover part but this is for the ECU and not for the gauge. The single pin sender is not a Rover part and feeds the gauge. This is the one you need to duplicate on the oil filter housing.
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Hi Revilla, thanks for the photos, my water rail is a different design and I have the brown ECU sender and a black sender with the same connector type for the gauge. Looking at Caterham parts they used to supply this type of sender but have changed to the type you are using in 1996 I think. 

I think the sender I have fitted is the wrong temperature range (150 degrees as opposed to 120 ) The Rover GTi Metro used the same sensor with a 1/8 ntp fitting. I measured the resistance of both sensors with the engine hot, and the oil sender had a higher resistance so that would explain the lower reading ( I think )

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@p.mole1:

Ah I hadn't realised that there was an earlier Metro-based setup with different sender. I'm a little surprised to hear that a Rover Metro sender matches a VDO gauge but if it does - that's good. Fingers crossed it all works as expeced when it arrives.

@TomB:

I have a mechanical oil pressure gauge. The takeoff point for the capillary is as shown below. On an oil filter housing from a Rover installation the port on the top that I have used for the temperature sender is normally blanked off with a threaded plug; I think it might have been used as part of the oil supply for a turbocharger on other models but I'm not sure of that. Actually it does tend to vary from on housing to another which ports are present and blanked off, or just cast off and blind. There's another port underneath but that is horribly exposed on a Caterham; I think any sensor in there would be the first thing to hit a speed bump!

My car has had a mechanical pressure gauge since I got it. I presumed that the normal location for the electrical oil pressure sender would be in the same place. Isn't it a bit of a tight fit I in the top? Unless it's mounted remotely and plumbed in there? I think the ones I've seen have been where my mechanical gauge takeoff is, but as I say I've always been mechanical so I'm not that familiar with the electrical setup.

OilPressure.jpg.9d92aa83b6f0f2ab27fa275158813d66.jpg

 

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Hi Andrew,

The standard position for the electrical sender is where your brass union in the foreground is fitted.  CC offered a "remote sender kit" so that it could be mounted well out of the way, usually near (or on) the RH engine mount. A flex ran from the sender down to the original mounting point on the filter housing. The idea was not only to locate the sender somewhere less exposed but also to mitigate engine-induced vibration (a well-known killer of this sender).

JV

 

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Hi Revilla thanks I'm assuming my car is original! it was over 20 years old when I bought it, but the wiring loom does not appear to have been messed about with. Hopefully the new sender will match the one fitted to the car unless it's it was a non standard one specified by Caterham.

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  • 5 months later...

Bringing this back up to the top, p.mole1, would you have a part number/supplier info for the sender you eventually used?

I'm in the same boat as you, my 1995 car has unmatched senders so I can never get anything on the gauge when switched to read oil temp. I’ve replaced the oil sender but still no joy.

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