Temperature Gauge

[Trevor450]

I have an odd problem. (With the car before you all start )

The gauge seems to have been acting a bit slow lately but today, it refused to go over 50ºC. The fans are cutting in and out and the car isn't overheating, using coolant and the heater is lovely and hot.

Do you think this is a sender or a gauge problem?

I have a track day on Sunday which I am going to risk but I am a tad nervous about it now.

Edited by Trevor450 on Thursday 27th June 17:01

[chris1972]

Have you checked the connection for the sender and the coolant levels?

[Trevor450]

Yep. The rad and swirl pot are both full and the blade connector behind the dizzy seems fine.

How do I test the gauge? Do I just remove the spade connector on the temp sender and short it to earth?

I am tempted to go to Maplins tomorrow to get a 170ohm resistor and attach it to the RR sender to get me by for the moment.

[chris1972]

Using the resistor approach will only tell you the correct temperature at one point. The rest of the temp readings are out and it under reads above the temperature you set it at. You may have a slight airlock, although, mine did the same for no apparent reason. If your fans are cutting in and out, it means the ECU is reading the right temp and the otter switch is working correctly. Do you have coolant in the expansion tank?

The best sender to use is the Land Rover one as it remains submerged in the coolant (positioned next to the ECU temp sender); however, it isn't calibrated to the gauge (neither is the TVR sender to be honest). I replaced the LR sender recently with a new one and intend to use it with the existing gauge, but calibrate it using a Temperature Gauge Wizard (see thread below).

http://www.pistonheads.com/gassing/topic.asp?h=0&a...

[Trevor450]

Thanks for that - something to look at in the longer term.

When I checked the rad and swirl pot, there was a couple of inches in the expansion tank when cold.

[chris1972]

Sounds about right. The TVR temp sender isn't located in a particularly good place and suffers from heat soak and isn't always submerged. Changing to the LR sender is probably the best alternative.

[Trevor450]

I've just checked the gauge by shorting it to earth and it went to maximum so it sounds like the sender has gone. I'll pick myself up a pack of resistors tomorrow and attach it to the RR sender so I will at least have a working gauge of sorts for Sunday.

[Trevor450]

Fitted a 160ohm resistor inline with the RR sender and I now have a reasonable temperature gauge. Fans come in at an indicated 85º and normal operating temperature on the move is 80º.

[chris1972]

If you get the Rovergauge lead made by Blitz you can read the temp as given by the ECU sender. I think the fans cut in at 95 degrees, with normal running temperature at 90.

[Trevor450]

Might have a look at that. Cheers.

[SILICONEKID343HP]

So the location of the TVR sensor is wrong so why not fit the TVR sender in the correct place .

[Trevor450]

It won't fit. The TVR sender is much bigger than the RR one. I think the fuel rail would also cause a problem too.

[SILICONEKID343HP]

Trevor450 said:

It won't fit. The TVR sender is much bigger than the RR one. I think the fuel rail would also cause a problem too.

Is the Land Rover one already fitted with a single pin type end or is that removed for another.

[chris1972]

Land Rover one half the size of the TVR sender and has a round 'male' connector Daz. This is why I've bought the Spiyda Temperature Gauge gadget, so I can calibrate it to the sender and get the gauge to display that the ECU is reading.

Would upload an image, but Thumbsnap not working.

Edited by chris1972 on Friday 28th June 16:22

[SILICONEKID343HP]

chris1972 said:

Land Rover one half the size of the TVR sender Daz, but is better positioned next to the ECU sender. This is why I've bought the Spiyda Temperature Gauge gadget, so I can calibrate it to the sender and get the gauge to display that the ECU is reading.

How do you know the ECU one is correct ?

[chris1972]

I use Blitzracing's lead for Rovergauge. Like most cars, running temp is 90 degrees. Fans cut in a 95 degrees. The positioning of the ECU sender is submerged in coolant as is the LR sender, whereas the TVR sender is fitted in the bottom of the inlet manifold near the thermostat. Not the best place as I would imagine it spends most of its time being partially submerged.

[SILICONEKID343HP]

chris1972 said:

I use Blitzracing's lead for Rovergauge. Like most cars, running temp is 90 degrees. Fans cut in a 95 degrees. The positioning of the ECU sender is submerged in coolant as is the LR sender, whereas the TVR sender is fitted in the bottom of the inlet manifold near the thermostat. Not the best place as I would imagine it spends most of its time being partially submerged.

Mine reads 70 on a run cool day ,75 warmer days on a run and max 80 in traffic .I do have the cooler otter switch but should not make a difference.

Standard 95 0n 88 off , Mine is 92 0n 87 off ,the fans come on so the gauge is miles out.

[chris1972]

SILICONEKID343HP said:

Mine reads 70 on a run cool day ,75 warmer days on a run and max 80 in traffic .I do have the cooler otter switch but should not make a difference.

Standard 95 0n 88 off , Mine is 92 0n 87 off ,the fans come on so the gauge is miles out.

I never trust the gauges. In fact, I've noticed that when I turn my lights on, the values of the gauges increase slightly. At least with the LR sender and the Spiyda bobbie I can try and get them more accurate. This gadget also allows you to add a buzzer, that will activate at a calibrated temp. Handy for the rare occasions otter switches fail!

[ChimpOnGas]

chris1972 said:

I never trust the gauges. In fact, I've noticed that when I turn my lights on, the values of the gauges increase slightly. At least with the LR sender and the Spiyda bobbie I can try and get them more accurate. This gadget also allows you to add a buzzer, that will activate at a calibrated temp. Handy for the rare occasions otter switches fail!

I've been working with Spiyda on this, matching the Range Rover sender correctly to the TVR gauge.

I'm currently testing our pre-production version that includes a buzzer, early indications are it's going to offer a far better solution than the simple resistor method.

There may well be a discount for PistonHeads TVR forum members.

[chris1972]

ChimpOnGas said:

I've been working with Spiyda on this, matching the Range Rover sender correctly to the TVR gauge.

I'm currently testing our pre-production version that includes a buzzer, early indications are it's going to offer a far better solution than the simple resistor method.

There may well be a discount for PistonHeads TVR forum members.

Doh... wish I had known Dave, I have bought one already (without the buzzer at the moment)! Can you tell me how to wire it in?