Temp guage probs

[Danny-C]

as title it keeps going up when eva i put something electrical on have tried running seperate earths but no difference has any one had this, it also sits very high on temp even tho its not too hot thanks dan
P.s Its on a m52 conversion

[toby]

Does the needle fluctuate quickly or slowly?
Did you use E30 temp gauge sensor or the one from the donor engine?

[Danny-C]

From e30 the temp guage came from and it fluctuates very quickly u press the brakes or put the heaters on and it goes up and stayes until u turn it off, it also goes up too far in to the red but when u turn the car off and turn ignition on it sits where u think it should, any ideas thanks.

[Brianmoooore]

Tighten the brass nut on the back of the cluster, immediately behind the temp gauge. If that doesn't cure it, check the main earth terminals above the glovebox are tight, and as a last resort, check/change the SI board batteries.

[Danny-C]

have tried the brass nut will check the terminals where r they (take the glove box out) Wot is and where r the si board have u had this before?
thanks dan

[Brianmoooore]

Earthing terminals are at the middle of the back of the glovebox area. Follow the brown wires.
SI board batteries are soldered to the SI board, which is in the front half of the instrument cluster when you open it up.
before condemning them, you should put the board into the freezer for half an hour (or just leave it outside at the moment), and measure the voltage across the two batteries.
NiCd ones should be 1.2 volts each, lithium ones should be 3 volts.

[Danny-C]

i did try another instrument cluster today as i had another lying arround as i took mine out and it still did the same but will check it all ova thanks

[Danny-C]

earths all seem good, tried the brass nut and another cluster still no better, any ideas guys??????

[DanThe]

You sure those SI boards are both working ok?

[Brianmoooore]

You say this is on a M52 engined E30.
I pressume you have fitted an E30 'brown' temperature sensor. How have you wired it?

[Danny-C]

I presume both si boards r working they were but it was some time ago bout 6 monthsish will have a good look at the the weekend just to clear it up.
Yes i did fit the brown sensor and danthe did my loom 4 me so i wouldnt that thought there was a problem there, really annoying problem only this and a fan left to do. Was trying to get a viscous fan but am going to end up buying a electric one tommorow , wanted it to look original

[DanThe]

Why dont you buy the TD blade?

[Danny-C]

cant get one no one seems to be able to get it and i have heard it might catch rad under breaking? would like one tho

[DanThe]

You cant get it from the dealer? You wont have any rad contact with decent engine/box mounts

[Danny-C]

Thanks all but the dealers want £44 just for the blades which is a bit expensive and they not sure its the one i need, so i think i just going to get an electric and get it back on the road. cant wait been over a year how slow am i

[Danny-C]

Hi guys i have checked the earths behind the glove box gave them a clean but all looked good and had a look at the si batterys they came out with a reading of 2.94v thats around right isnt it? running out of options should i buy a new temp sensor? any ideas dan

[Brianmoooore]

The temp sensor itself won't be the reason for the temperature reading varying with electrical load.
Going back to the OP; is the change in temp gauge reading instantaneous when an electrical load is switched on, or does the needle slowly move to its new position?

[Danny-C]

Yes it does move instantly say its about half way u turn the fan on it goes up then turn the lights on and it goes up further and so on, wen the car is at normal running temp it sits around the red on temp guage with nothing electrical on, i turn it off and put the ignition on and it reads half way which u think it would im lost!!!

[Brianmoooore]

There has to be a resistive common path somewhere, for both the current being used by the electrical load that you turn on, and the current through the temperature gauge sensor. The heavy current is producing a small voltage across this slightly resistive path, which is consequently changing the current flowing through the temp. sensor, and hence the reading on the gauge.
The only place this resistive path could conceivably be, as far as I can see, is in the engine to body earth strap, but this would surely show up when you crank the car!
Where next? You could remove and clean up the earth strap, but I can't see how it can be faulty.
Next, I suggest you disconnect the temp gauge wire at the C101 engine plug, arranging things so that you can get at both ends of the wire.
Find a resistor with a resistance of 60 ohms (two 120 ohm resistors in parallel) and connect it between the car side of the temp gauge wire and earth (rear bonnet bracket). This should make the temperature gauge read around normal when you switch the ignition on.
Drive the car like this, and see if the gauge continues its antics, or remains stable.
Next test is to connect an ohmmeter between the engine side of the split temp. gauge wire and earth, so that it acts as a replacement temp. gauge. See if this varies with electrical load.

[booomer]

Why dont you buy the TD blade?

I'd prefer to have an OEM viscous fan. Are you reffering to just the plastic bolt on blade set from an e34 525td?

[DanThe]

Why dont you buy the TD blade?

I'd prefer to have an OEM viscous fan. Are you reffering to just the plastic bolt on blade set from an e34 525td?

Viscous fan yes, but the plastic blade from a 324TD

I used to have a flickery gauge in my old 4 door, a good thump on the dash above the clocks usually brought it back into play
Similar problems like it would flicker with the blower on full

[Danny-C]

Thanks all yeah a good hit usuall sorts things out lol or turn it off and back on but this is the first thing i tried justb seems to be one thing after another its like she never wants to be on the road again, will try those things Brianmoooore sez is there any thing that man doesnt know!! Where would i get a resistor like that from?
Thanks all

[Brianmoooore]

We tried tightening the temp gauge nut a long way back the thread! Didn't we?? And aren't we on a second cluster? When the nut is loose, the gauge needle jumps between where it should be and about a fifth higher, bur either randomly or in response to general knocks and vibrations.
Easiest source of resistors in this sort of quantity is probably Maplins. You only need 1/4W or 1/8W, and they will probably sell them in packs of 5 or so.

[DanThe]

If it moves when your thumping the dash its more likely to be a loose connection in the clocks somewhere, I tightened the nut on the back of my gauge 'very tightly' and it still didnt completely solve the problem

[booomer]

Does anyone know the part number of the e30 temp sender that is to be used or the specific model it comes out of?

[RoadHazard]

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