Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing Water temp sender for old 4/4

The temperature sender on my 1967 pre-X-flow Cortina GT engine has stopped working. It is the original Ford part which gave good enough but not really proper readings on the Smiths temp gauge. Does an expert in this forum know if there is a Smiths sender with 3/8" NPT (whot's that??) thread or do I have to resort to an adaptor (Holdens have one)?

Or would it be better to stick with the Ford sender (of which there are different types and I don't know which one to order)?

Thanks in advance for your advice.

Frank

I'd stick with the Ford item in the first instance. Is the temperature gauge reading low or high? If it's high I'd suspect the instrument voltage regulator.

NPT National Pipe Thread. Basically describes the pitch etc of the thread f the senor.

Are you sure it's a Ford part? If the gauges are Smiths you will need the Smiths sensor I believe. Melvyn Rutter can advise.

Other reasons could be poor earth connection ( is there plumbers tape on the sensor's thread?), too much resistance in the wiring (has the sensor wire been damaged by heat?) and as noted above is the voltage regulator ok?

The Ford and Smiths senders whilst typically the same thread will report different resistances for the same temperature and hence need to match the guage.

Are you sure the engine is not over heating?

@tmg,
It was reading about 10 centigrades low, which didn't matter much because I knew. But it would be nicer to have the correct temperature. Problem with the Ford sender is that according to the Cortina owners club there is one for engines from 1964 to 66 which works with 5 volts while the Smiths gauge works with 10 volts.Pre 1964 senders seem to work with 10 volts, same as the Smiths. Cortina owners seem to put all 1967 engines as cross-flow - and it is well possible that the engine in my 1967 4/4 (september delivery) stems from 1966. Engine number is listed under "industrial engine" and no year.

@ Richard,
Yes, I think it has to be Ford because the sender was there when I bought the car new. In 1967 there was no water temperature gauge fitted to the 4/4's and it was not on the accessories list. I bought a Smiths gauge because the Ford part didn't match the other instruments and at that time there was - at least here in Switzerland - no Smiths sender with the correct thread available. I have searched the Internet and all Smiths senders I found have the 5/8" thread instead of the 3/8" I would need. I would try the adaptor but I doubt that there is enough space to fit it.

My sender is definitely kaput. It shows an infinite resistance while other senders I have show around 300 ohms (VDO) to 584 ohms (smiths) at rooom temperature. The gauge works o.k., I tested it against the engine block and on the (Smiths-)sender for the oil temperature.

Thank you both for bothering to answer my questions.

Frank

Does indeed sound like the sender.