Temp gauge drops with power...

Hi all,

It's been a zillion years since I checked out the forums - lots of new names, but great to see it's still going strong!

Anyway, I noticed over last weekend that when accelerate my Z the temp gauge needle drops as the engine is loaded up.

Examples:

1. If I have the cruise control on and it increases the power slightly to hold speed when going up a hill, the temp needle flutters around lot and drops slightly.

2. If I'm driving and plant my foot and the engine is loaded up big time, lots of boost, the temp needle drops to zero.

3. If I simply apply moderate power, the needle will drop about half way to zero and flutter a little.


What the...?


It doesn't appear to be dependent specifically on boost or rpm, but more the load on the engine, or perhaps the flow rate of fuel to the engine. I do realise it's all kind of the same thing and will all alter when another of these things alters... but it's hard to explain. I'm sure you know what I'm getting at.
For example, the rpm doesn't change much when the cruise control increases the power to hold speed up a hill, but the temp needle still goes a little nuts.

So, has anyone experienced this???
Any ideas what on earth is going on with my crazy temp guage?

I pulled over a couple of times during my trip to check the engine, and everything was perfect, no overheating, ran like a dream... except for the gauge.

Any input on what this problem might be would be brilliant.
Cheers all,
Mark

 

it might be a loose or dirty connection on the sensor try cleaning that

 

Mine does a similar thing since I installed an aftermarket thermostat.

Have you changed the thermostat recently??

Mine only does it rarely and mostly on cold days. It seems that the thermostat is a little lazy to close so when the engine revs suddenly rise it appears the engine then gets a big dose of very cool coolant from the radiator causing the engine temp to drop suddenly. After a couple of mins the temp comes back up to normal.

Never happened with an original thermostat. Which reminds me I should put the new original one back in.

Cheers,
Dave.

 

Dodgy earth somewhere would be my guess. Certainly is a strange one though.

 

I had the same problem recently. Turned out to be the spade connector on the temp sensor had become loose. I used a nail punch and hammer to tighten the rivet thing holding the spade to the sensor. Good as gold now.

 

Under load, your fan is moving the temp

sensor spade as it is loose...