Thread: IIa v III temp senders and gauges

The late SIIa with toggle switches and the SIII guages had a voltage stabiliser/resistor in them so work at a lower voltage, use them with mis-matched sensor and they'll either read low or full scale.

Thanks Diana. I've got the later gauges (its a '69) and the voltage stabiliser is OK (the fuel gauge works).

Just had a thought - if I pull the sender from the block, attach the wire from the guage, earth the sender body and place it in a bowl of hot water that should give me a reading on the gauge. Right?
That should allow me test my senders to see which one is working without having to drain and refill coolant and drive about multiple times.

Now if there were only a way to do this without having to drain the coolant. It does seem to splash everywhere even using a funnel

It needs an earth to the body of the guage.

Can check numbers tonight at home.

Are you sure it's a 241 prefix engine? They usually have the 251 prefix out here.

Also you may find that it's not a temp guage sender its a temp switch for the cold start lamp.

Definitely a 241 - its got an 8:1 head, the 901 is 8:1 as well.
Its a bit weird, it has a A suffix gearbox, but with a later sealed clutch withdrawal unit, and the chassis number comes up from CALvin as a CKD

I'm talking about the sender under the thermostat. Not the triangular unit visible from the top, which is the cold start switch, right?

I thought the senders earthed through the block? None of mine have the wiring to send an earth wire back to the gauge.

Had a look through the parts book last night, and it turns out there was never a temp sender that screwed directly into the block. So what my 11a engine has is anyones guess. However it tested OK, so I'll leave it alone and reuse it once I rebuild that engine.

Theres a sender (part number 560794) and 2 possible adapters, 568457 for imperial threaded heads or ERC8973 for metric threaded heads.

Testing the gauge was easy, just take the wire connected to the sender and earth it somewhere. Turn on the ignition( no need to start) and the gauge should move to the top. Turn off, reconnect wire.

Testing senders is pretty easy too. Set your multimeter to read about 2000ohms.
If testing a sender outside the block, put the red wire on the terminal and the black wire on the sender threads, I got a reading of around 500ohms with one sensor and about 1500 with another (one that didn't work had a reading of infinity). Then put the sensor end in a cup of hot water, you should see the ohm reading falling as the resistance gets less.
If testing insitu, with the engine cold, red wire on the terminal, black wire on the spanner flats, take a reading. Go drive around for a while come back and repeat the reading, the resistance should have fallen quite a bit. If not its new sensor time.

Hope that helps someone
Cheers

Originally Posted by Ozdunc

Definitely a 241 - its got an 8:1 head, the 901 is 8:1 as well.
Its a bit weird, it has a A suffix gearbox, but with a later sealed clutch withdrawal unit, < Is it an A suffix gearbox or an A suffix case, with suffix H internals?> and the chassis number comes up from CALvin as a CKD. All the RHD vehicles had engines and transmissions that followed the RHD Home market sequence irrespective of market or CKD, the interesting point is that in Australia both the 109" and 88" usually had 109 engine sequences.

I'm talking about the sender under the thermostat. Not the triangular unit visible from the top, which is the cold start switch, right? Was just checking, because the early SIIa engines didn't have a temp sender, they only had fuel and ammeter, the temp guages were an option and were capilliary types.

I thought the senders earthed through the block? None of mine have the wiring to send an earth wire back to the gauge. Correct, but if you have the sender in a bucket of water you need to add an earth to mimic the block.

In red

< Is it an A suffix gearbox or an A suffix case, with suffix H internals?>

No idea, how could I tell (without taking it apart )?

Here's the numbers if that sheds any more light on it

Chassis 24317091G
Engine 24114682A
G/box 25400489A

I don't have the axle numbers, but I could get em if that would help.