E30 Temperature Sensor for the M50

[MaxBell]

Hey guys;

I have this temp sensor from an E30, but I'm not sure it's the proper one. It's really orange, rather than brown.

And it just threaded into the head, I didn't have to tap it at all.



The temp gauge in the car flicks around and randomly jumps from hot to cold.

[rightcoastbias]

Aftermarket sensor manufactures will use whatever color plastic is cheapest. I've seen black E30 sensors. E30 coolant temp gauge sensors are single pole, like the sensor you posted. Check continuity on the plug to make sure you haven't swapped the ECU and gauge plugs.

As you observed, the E30 sensor is thread size 12x1.5mm and will thread into the temp sensor ports of M5x/S5x head.

The commonly mentioned re-threading of the E30 temp gauge sensor (to thread 10x1.XX mm) is to fit the E30 sensor into the throttle body heater port of the M52/S52 head (as seen exiting the block to the right in your image.) This is necessary for an OBDII head, as there is no provision for the E30 gauge temp sensor. An OBDII head has a single temp sensor port and the throttle body heater port.

Anyways, buy a new e30 sensor for less than a sawbuck at NAPA.

[MaxBell]

I'm going to buy both the ECU one and the gauge one. I find that the gauge jumps around, and when it does, the engine bogs.

Thanks for the thorough response.

[7pilot]

I'm going to buy both the ECU one and the gauge one. I find that the gauge jumps around, and when it does, the engine bogs.

Thanks for the thorough response.

This problem could be caused by loose connections and plugs at the back of the instrument cluster.

m

[goldtl]

I'm going to buy both the ECU one and the gauge one. I find that the gauge jumps around, and when it does, the engine bogs.

Thanks for the thorough response.

were you able to fix this problem? i am having the exact same issue

[328ijunkie]

^ Sounds like a general electrical issue. The cluster temp gauge should have nothing to do with the running of the motor.

[7pilot]

^ Sounds like a general electrical issue. The cluster temp gauge should have nothing to do with the running of the motor.

That may be so, but the connector at the back of the cluster has several other functions passing through it.
I'm too lazy to check, but if the coolant temp sensor for the ECU shares this plug, then the problem will not be remote to the gauge.
The ground connectors for the cluster and its functions also needs to be checked.

m

[MaxBell]

were you able to fix this problem? i am having the exact same issue

Nothing yet. I've replaced every sensor at this point. The fuel pump had a broken part of the ground, but that didn't solve anything.

I'm going to start tearing into the wiring harness.

[E30stan]

tightening down the ground nut behind the guage in the cluster fixed my dancing needle

[MaxBell]

It was a grounding issue. The main engine ground, from the mount arm to the side of the chassis, was very rusty. I sanded it down, problems all solved.