Can I calibrate the temp (Water) gauge?

Saloons
1

My Mk 10 reads 10-15 deg too much. I have verified with a laser instrument. I suspect the gauge rather than the sender. Can the gauge be calibrated? I see 2 brass columns with slots for a screwdriver, at the back of the instrument. I thought I´d ask before having a go at it…
Peder

2

There is an adjustment facility, but check the IVR first.

3

IVR…?
Are adjustments dine with those 2 brass screws? Not a serious oroblem as I know that the temp is ok, but I would prefer the needle to sit at 82 rather than 95 when hot

4

Andrew is referring to the instrument voltage regulator. Within the confines of the instrument cluster there is a 10 volt regulator. Check the output is to spec otherwise instruments will read high. Paul

5

Ok. The car has a Volt meter which is spit on, if that suggests anything. Oerhaps it is not connected to the 10volt regulator…

6

I think the water gauge is managed by the IVR. The voltmeter shows battery/alternator volts. Paul

7

And can the small 10 volt ivr be adjusted to correct the temp gauge?
Or shall I try with another one?

8

Nope. They’re set. Some of us change them out for a modern three terminal device. There will be some stuff in the archives. Below the classic type. Check and see what the output of your one is. Paul
https://xks.com/i-7083101-jaguar-instrument-voltage-stabilizer-negative-ground-08-9965.html

9

Hi Peder,

The original IVR can not be adjusted or easily measured. It creates its 10 Volt average by producing full battery voltage for a short time and then shutting off for a short time. The ratio of those on-off times averages out to 10 Volts. There is no practical way to verify its accuracy. However, there are two likely failure modes – Fully on or fully off. On the IVR there should be full battery voltage on the “B” terminal, and the “I” terminal should be switching between battery voltage and zero. If you have continuous full battery voltage on the “I” terminal then you have found your problem. This failure will also cause your fuel gauge to be overly optimistic.

If you need a replacement IVR you might consider the adjustable and measurable unit from www.coolcatcorp.com.

https://www.coolcatcorp.com/Merchant5/merchant.mvc?Screen=PROD&Store_Code=CEC&Product_Code=SSIVR-N&Category_Code=EL

Mike Eck

New Jersey, USA

www.jaguarclock.com

'51 XK120 OTS, '62 3.8 MK2 MOD, '72 SIII E-Type 2+2

10

Thanks, as usual Mike.

The fuel gauge is very accurate…!?!