The matter with Water-Oil temp gauges low reading

During the life of my 1.8 April 96 I often encountered
a low reading on water and oil gauges.
(This since 2008 circa)

Typically 70 celsius... and no way to get any higher reading
even in a hot italian August max values was 80.

Because of this the Mecca changed the thermostat twice.

No difference... Mecca told me ...1.8 is a cold motor...
You know..

(?????) (WTFK???)

Then finally in the era of Multiecuscan I discovered that
the sensor for the ECU was reading 90 celsius (perfect value)
despite the fact the temp gauge was still reporting 70.

So I changed the water gauge temp sensor ......

NO WAY... same result...

So I suspect the gauges instruments after 22 got cooked...


For solving the problem .. apart replacing the instrument dash
You need to buy a sensor with a lower ohm temperature curve...
..........Or like I did ........put a 470 ohm
resistor in parallel to the ground and the signal on
the gauge connector (Both for oil and water).

Easy fix..... with an expense of less than 1 euro..
:-)

Cheers

KK

crikey-

so; you shifted the impedance of the sensors by going across them with resistors..?

okay!

Good effort for 1 euro..

Yep
Of course not ideal solution as replace the gauges.
But does work.
And is stable.
The min parallel resistance allowed is the one that
IS NOT raising the indicator from his rest position
when the engine is cold.

Sometimes happen the ground of instrument dashboard is NOT
zero ohm if compared to the chassis and this may cause
wrong reading @ high temperature where the sensor goes
very low , below 100 ohm.. but was not my scenario.
KK

I have the same issue, and I'm kind of glad I'm not the only one.

Both the water and oil temp gauges read low, and with the water sitting just over 70c most of the time.

The thermostat is new (and not a cheap one), the bottom radiator hose stays cold until ~70c on the dash gauge (so thermostat is not stuck open), then the fans come on at ~82c (which I assume would be 95ish on a properly working gauge?).

Gauge repair is way down the list, after fixing the oil leak from the filter housing, the leaking cam cover gasket (including cracked corner mount), the CHOD, the seeping heater matrix seals etc etc!

what you driving, Forth?

welcome along!

Same issue on my 2.0 16v N/A. Both the reading of oil and water temps are low, in normal driving gauges stay at around 70-80,with oil temp a bit higher,upon spirited driving or when I get into trafic,temps will rise to around 85c,90c when I am going uphill on a road with lots of curves.I think the fan kicks in at around 80-85c for me. Not sure is that a thermostat or gauge issue since N/A only has heat exchanger for the oil,not oil cooler.

This has been the behaviour of my 16NA for the last twenty-odd years...

The normal running temperature of the engine water - as measured by the ECU - is 79-84C on the 16NA.

Thanks, I've got a '97 20VT

Hi Forth and welcome to the forum

If you click on My Stuff/Edit Profile and scroll to the bottom you'll be able to add the relevant colour avatar to your forum name so that people will know which model you have when answering questions....