Odd temp gauge behavior - NADA V8

gbvona

Member
As engine warms up, the temp needle rises to spang in the middle of the scale. After a few minutes of driving, it rises to very near to the top (somewhat, but not entirely, in the red), sits there for a minute or so, then marches back down to sit in the middle. Repeats every 4-5 minutes.

New thermostat. Replaced the mechanical voltage stabilizer with an electronic one (reads right at 10.0 volts). Gas gauge was steady all along, no change. Unwrapped the wiring about a foot to check for bad insulation, nothing untoward found.

It MAY be that the engine is actually heating up and cooling down, but there is no indication of a problem in performance, and the cycle seems pretty fast for actual changes in engine temp. Hard to tell, I have never been in a situation to be able to check with an IR thermometer when it reads hot.

And yes, the path from the intake manifold tower to the radiator inlet is clear.

Any ideas? Might be a fault in the temp sensor. Since I am in the US, getting one is pricey due to shipping. Does this sensor cross with anything more common (e.g., MG/Triumph etc)?

gbvona
 
Thinking aloud.

Given the gauge behaviour is a regular cycle, I wouldn't have thought it's an engine overheat.

I can't tell for sure from your post, but was the gauge behaving like this before you fitted the electronic regulator? If so, it would seem to point to either the sensor or the wiring.

Earthing the lead at the sensor will send the gauge full-scale with ignition on, but that test alone's probably not going to help in this situation. However it could be an intermittent cable short to earth, although I'd expect the results to be more random than a regular 4-5 minute cycle.

If you did want to try a new transmitter the part number is 568055, and is available from Land Rover suppliers.

e.g. Land-Rover Sensor - Engine 568055 | Land Rover Reno Parts

Good luck, let us know how you get on!

Stan
 
sticking thermostat, low coolant level or blocked coolant bleed pipe on the top of the inlet manifold all of which can do that
 
sticking thermostat, low coolant level or blocked coolant bleed pipe on the top of the inlet manifold all of which can do that

New thermostat.

And yes, the path from the intake manifold tower to the radiator inlet is clear.


gbvona has already considered these Penguin, he hasn't mentioned checking the coolant level though;)
 
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