Temp gauge...

[DavidL]

is doing odd things - sits just over the first mark and then all of a sudden spikes to the 2nd mark or even as high up the gauge as it will go. It stays for 10-30 secs and then drops back to where it was.
Everything seems to be fine. System has been pressure checked and is fine and now has a new rad cap although I have not run the car with this in place.
I feel it must be electrical - my oil pressure gauge did something very similar when the sender failed. Could possibly be an earth.
So is the temp sender the connection just under the manifold on top of the engine?
Are they a) expensive b) hard to change. Looks a bit hard to reach!
Which is the most likely earth point for this or should I check them all?
I'm fairly certain there isn't really a problem but I must get this sorted as I hate driving watching the gauge! Fans kick in and out quite happily but don't always seem to be reflected on the gauge.
Thoughts?
Thanks David
Thanks

 

[simonthomas]

The same sort of thing happend to me I checked everything, it turned out to be a small brass nut on the back of the temp gauge, i had to take the instrument panel off and very carefully tighten the nut, it was very loose! I did it with a just a socket and my fingers. I did it when the engine was hot so i could see a result. I also noticed that if you over tighten it the gauge goes off (as in drops to cold). I guess the nut makes an electrical contact. Its worth a play before you start shelling out money changing parts! Good luck ! ! !

 

[cytefx]

had a similar item on mine recently, although it affected fuel gauge also, similar solution, one of the clips on the back of the pod had come loose (probably I had not put it back on properly when I fixed the speedo) and pushing this back on solved the issue completely, although I had brought another pod in the mean time incase it was the gauge.

 

[DavidL]

I think the dash is going to be the problem area as I can both fix and induce the spike by hitting the dashboard! Looking at Clarks it doesnt look too hard to get to the back of the instruments so I'll have a go.
It has been suggested that the temperature gauge is a known fault and that having a resistor added to the circuit at the back of the gauge helps/fixes it.
Does this sound at all familiar with anyone?

 

[cytefx]

have not seen the item about the resister, but I can take out the dash pod on mine now in about 10 mins, its very simple, about 6 screws on the cover (black plastic going over the airvents etc) and then just 4 screws holding in the pod, and last but not least the 3 cable joints (they can only go on one way round, dont force them, just ease them on and dont forget to push the clips to the lock position (thats where I think I went wrong first time round)

 

[simonthomas]

It is really easy to get the instrument pannell off off, just a few screws, i didnt take the steering wheel off either. It is a bit of a tight squeeze tho! it sounds like a loose connection or that nut to me! I would check that before I go soldering any resistors to anything tho! One thing you didnt say, what year is you 944? mine is 86 oval dash!