Accuracy of VDO Water Temp gauge

[jad]

Hi

The other day i replaced me standard land rover water temp gauge with this gauge and this sender,

http://www.merlinmotorsport.co.uk/p6142/VDO-WATER-TEMPERATURE-GAUGE/product_info.html

http://www.merlinmotorsport.co.uk/p6151/VDO-WATER-TEMPERATURE-SENDER-5/8-UNF-THREAD/product_info.html

I thought these would give a fairly accurate temperature reading, however on my 200tdi which has an 88 degree thermostat, when the engine is up to temperature the gauge reads about 82 degrees. At this point the top of the radiator is hot and the bottom cold. Since the top of the radiator is hot this must mean the thermostat has opened. So why doesnt my gauge read about 88? Has anyone seen this before? Are the gauges just not really that accurate?

Cheers

Jad

[Anderzander]

It could be the gauge - but thermostats are often quite different from their rating.

Have you measured your thermostat out of the vehicle?

[Ratty43]

It could be that the thermostat is opening at 82deg, it's pretty easy to pop it out and check it in a saucepan.

[Ratty43]

Beaten to it.

[jad]

I have never had to change the thermostat and its probably not worth disturbing it unless it fails. so maybe ill just leave it.

Anybody have a VDO gauge and that knows what temp there thermostat opens at? and knows what the gauge reads?

[Anderzander]

you could heat some water, with a thermometer, and pop your sender in if you want to check it?

[Briarston]

you could heat some water, with a thermometer, and pop your sender in if you want to check it?

I've got a Durite gauge fitted. That steadies at about 82c,with the top of the rad.

hot same as yours. The thermostat doesn't open with a bang, so perhaps 88c is when

it's fully open?

[jad]

I've got a Durite gauge fitted. That steadies at about 82c,with the top of the rad.

hot same as yours. The thermostat doesn't open with a bang, so perhaps 88c is when

it's fully open?

that would make sense actually. good thinking

I hadnt thought of that as with the old land rover gauge it used to spike and then level off. So i was just assuming the thermostat was open or shut.

cheers

Jad

[bobtail84]

Anybody have a VDO gauge and that knows what temp there thermostat opens at? and knows what the gauge reads?

We have 2 V8's with VDO water temp gauges and MegaTune reads the temp as 85c and the VDO reads about 5c less. The temp senders have been calibrated with the ECU so are about as accurate as you can get with a LR part... They both have 88c stats. Also keep in mind that the gauges are more for reference than any thing else so if you can get hold of a IR thermometer take a reading when up to temp and look at the gauge then you will have a better idea of the temp reading. HTH

Jeff

[Superpants]

From experience with a similar issue, the senders can be up to a few degrees out, the gauges likewise and the thermostats too- it is therefore entirely possible to get an error of the order of 6-7 degrees. The only sure way of checking would be to insert a calibrated thermocouple into the system when running.