Water Temperature gauge

[Tasi Autele]

I purchased a water temp gauge from napa and quick connected it. running the + to a hot wire - to ground and s to the lead on the thermostat. after running the 109 for less than 2 minutes the gauge pegs at 250 (the top temp). I cracked the radiator and it was barely warm. I haven't had an opportunity to track down the wires and connect it correctly...does anyone have any advice please? Should I check the thermostat, could it be bad?
Thank You,

Tasi

[SafeAirOne]

The gauges and the senders are designed to operate together. Your Land Rover uses a 30-300 ohm sender (30 ohms=cold, 300 ohms=hot). Your aftermarket gauge apparently doesn't.

You need to install a sender with an ohm range matching the specifications of your particular sender.

Which sender did you get at NAPA? It should be easy enough to tell what the correct sender range for that gauge is.

[Tasi Autele]

Thank you. It's a vdo pro-cockpit. I'm looking for the range now online... I haven't been able to find it so far.
Also, I have the mechanical sender/gauge units, but I put a different 2.25 in, and I cannot get the sender to seat in the engine, it just floats freely. There is the doughnut nut above the sender that fits, but I cannot figure it out. Here are the pics of the mechanical sender...I would love some feedback. Nope it does not go in that hole...perhaps this one with the plug?

[SafeAirOne]

What is the highest temperature on the VDO gauge? 120c (250F), 150c (300F) or 200c (400F)?

The VDO temp senders are matched by the maximum reading shown on the gauges. Using this data sheet from VDO, you can look up the sender characteristic curves for the different gauge/sender pairs:


Most of the 120c (250F) gauges have 356 ohms at 38c (100F) and 33 ohms at 107c (225F).

Most of the 150c (300F) gauges have 594 ohms at 38c (100F) and 54 ohms at 107c (225F).

Most of the 200c (400F) gauges have 1555 ohms at 38c (100F) and 128 ohms at 107c (225F).



You just get whatever adapters necessary to use the correct VDO sender or mechanical sender.

If you used your original Rover sender with a 250F VDO gauge, it would read almost perfectly, except backwards!

[Tasi Autele]

ahh, that would make sense...backward. Yes it is a 250. Is there a way to correct the gauge?

[bugeye88]

On the subject of engine temp and gauge accuracy.... Does one of those laser temp guns give an accurate reading of coolant temps when applied to the area of the temp sensor on the block? Or is there too much difference between the actual coolant temp and the temp the laser reads on the surface of the block? If the laser is close enough, it would be of help in determining accuracy of the gauge.

Cheers,

Rob
Bugeye88

[SafeAirOne]

ahh, that would make sense...backward. Yes it is a 250. Is there a way to correct the gauge?

A piece of masking tape and a Sharpie?

[LaneRover]

A piece of masking tape and a Sharpie?

Or just one of those silver sharpies!