Wonky Temp Guage

Post Thu Oct 27, 2005 9:38 am

Any help appreciated.

How do I determine whether I have a faulty guage or whether something elso is wrong such as SI board /batts

1- Guage behaves normally until operating temperature is reached.Stays there a bit and then goes up to 3/4 and a bit beyond.Then flickers about between there and the 1/2 mark again.

2- Engine is not overheating and there is no coolant loss-no other nasties such as mayo or water in the oil.

3- Service lights stay on after startup and then go off after a bit

4- Econometer not operating properly-only moves (and then correctly) under full throttle.

Post Thu Oct 27, 2005 9:46 am

i would tend to lean towards SI board batterys being nackerd.....

Post Thu Oct 27, 2005 6:51 pm

many years ago i built a kit car and it kept telling me it was running too hot but it wasnt.the petrol gauge didnt seem right as well.
long story short, it had a "voltage regulator" on the back of the dash and this was not tight! giving a false reading for the gauges.
I dont know if e-30s have one but its worth a look!
Martin.

Post Thu Oct 27, 2005 11:31 pm

Flickering temp gauge, is simply a matter of tightening up the brass nut on the back of the cluster. Very common.
E30s have voltage regulators, but not the primative affair that would have been used in the kit car. Never known one to fail.
Worth opening up the cluster while its out and at least checking the batteries. Stick the cluster in the fridge for an hour, and then measure the voltage across each battery. Might sort the econ gauge by replacing the batteries if they're dud, but there are other things which afflict this.
Do a forum search on "220 ohm resistor" while the cluster's open as well.

Post Thu Oct 27, 2005 11:38 pm

Got the same thing on my 316, but fuel as well, both go mad up and down. If it was the batteries the tako would stop working???

Post Fri Oct 28, 2005 12:03 am

herman wrote:Got the same thing on my 316, but fuel as well, both go mad up and down. If it was the batteries the tako would stop working???

Fuel gauge has a similar nut.
The problem with the batteries in the earlier NiCd board isn't so much that they loose voltage, but that they tend to go short circuit and pull down the supply rail to a few circuits. The effects depend on how bad the batteries are.
You've got to take the cluster out to tighten the nuts, so you may as well check it inside while you're at it.

Post Fri Oct 28, 2005 11:14 pm

Thanks for the advice, I'll look at that