Temperature gauge drops when turning left

Driving around in the old 300TDi D1 these past few days I just noticed that when I pull quickly left e.g.exiting side road, the temperature gauge drops to 0, then as the vehicle straightens out rapidly ascends to the middle of the gauge again.

There is also a slight dipping and then it pops back midway as you drive along.

The coolant is correctly to the middly of the expansion tank, I also popped out the radiator and thermostat housing plugs and there are no air gaps. The system is pressurising fine and Anti Freeze up to date.

The cable from the wiring loom looks good.

The engine is a healthy 120k with the pump turned up slightly.

I replaced the serpentine earlier in the year when I put a new alternator on.

In general the car doesn't do many miles these days, but as the 110 is off being fettled I am running it around at the moment

Any ideas?

Sounds like the wiring loom is flexing with the turning forces and the cable is cracked internally or perhaps shorting on a chafed area to me. About all I can think of that would cause such a rapid change in reading.

Yes it litterally drops to nothing then shoot back up, I will be investigating further tonight

Quick question. Did you use your indicator light or simply turn left?

It's definitely a grounding problem - had similar after having the clutch repaired the guys "forgot" to hook up two ground wires to the transmission... One apparently controlled the circuit to the display...

Get it hot, stop the engine and then turn the ingition back to the 'run' position so that the gauge reads. Get the missus (or partner if you are that way inclined ) to watch the gauge as you gently go around flexing the looms in the engine bay. Hopefully the needle will drop and that should identify the area you need to look at in greater detail.

Gary Gilbert said:

Quick question. Did you use your indicator light or simply turn left?

Click to expand...

Indicators, what are those ;-)

No not related to that, I did notice bouncing over some speedbumps in the local town that the needle fluctuates too. so definately an intermittent earthing issue.