Do I trust my thermostat?

[Funnybear]

I had a blown water pump a while ago, and whilst no lasting damage (touch wood) and a good fix was made the thermostat has never been quite right since.

It would flick around a hell of a lot, but only for short bursts before settling down back to the normal midway. I assumed it was air pockets in the water or steam, or whatever. They seemed to settle down, but I've never really trusted it since.

So now, I set off on my regular pilgrimage to cardiff to pick up my daughter, and it skyrocketed straight of the bat. It sat in the red from cold. Obvioulsy I'm not overly perturbed, as I know the engine is cold, and it does settle down again as I'm heading out of town.

It now indicates to me that my car seems to be aircooled as everytime I'm sat in a que of cars it starts creeping up untill I'm moving again, and I don't need to move fast, just a steady jam creep will drop it again.

I don't think it's running hot, not like when the water pump blew. I've had the blower on and it's blowing dry and steady heat.

I am wondering if the viscous has stopped working as I've not heard it it when the temp rises. But if the engine isn't actually hot then it wouldn't run anyway, would it?

How easy is it to fit a new Thermostat? As obvioulsy thats my first port of call.

Anyone put there finger on this straight away? I've got to do the return leg on sunday and I don't want to ruin my engine.

[Brianmoooore]

Your first port of call should be the small brass nut on the rear of the instrument cluster, directly behind the gauge.
How easy it is to change the 'stat depends considerably on which engine you have, which you've omitted to tell us!

[magpie]

stat bolts can snap off a cold engine .

[Funnybear]

It's a the 2.5. Sorry. Should have mentioned that.

So by instrument panel do you meant he clock facia? So I pull that out and tighten up all the brass screws I can find? Or something on the stat itself?

[Grrrmachine]

http://www.e30zone.net/e30zonewiki/inde ... ot_Working

[Funnybear]

Thankyou. I will have a ferret around having seen that wiki.

Cheers.

[Brianmoooore]

Wiki article needs a little 'adjustment'! It refers to removing the plug from the brown sensor, and shorting the two terminals in the plug. All but the very first E30s will have just one terminal in the plug and just one wire running to it, so the wiki should read 'short the pin in the plug to a body or engine earth with a piece of wire'.
"....... but access to this nut requires the dash cluster to be removed, which is why testing the wiring with the above method first is the preferred solution." If the engine in question is a M40 or 42, I'd say that accessing the back of the cluster is far easier that getting at the brown sensor plug! If the problem is the temperature gauge flickering instantly between the 'normal' reading and one a little higher, then I'd recommend going straight for the brass nut on the cluster, and perhaps a further link in the wiki to the 'other' jobs with the cluster out - checking the SI batteries, the soldering of the 220 ohm resistor and the similar nut on the fuel gauge.

[Funnybear]

THanks for the info guys. I did notice the single pole in the sender unit, gave it a good blow out and checked it, all good. No corrosion, looked like new actually. But made sure it was seated properly. Gave it a water top up too, but that wasn't that low.

I've taken it out and it's not messed me about once. So I've obvoiusly done something.

I can make the needle jump about a bit if I tap the dial fascia, would that indicate a loose brass nut?

[Brianmoooore]

Almost certainly.

[Funnybear]

So obviously pulling the facia off to do that is quite a daunting endeavor for me with little or no automotive mechanical tinkerage experiance. So, just out of interest how is the viscous wired up with the thermostat? Does it take it's read from the dial? Or from before that?

Or is connected at all to the 'stat? Where does it take it's temp cut in from?

Thanks again for your help guys.

[Brianmoooore]

Taking the instrument cluster out is simple - see wiki.
The 'stat for the viscous is self contained in its hub.