Section : Dashboard and Instruments

water temp guage 

Posted By : Steve Brooks, 05-Oct-2004, 07:40pm

hi
How easy would it be to fit a water temp guage to my 1965 herald 12/50?
I think there is supposed to be a sender (or a place for one ) under the thermostat housing somewhere
- cant find it though but to be honest I havent looked that closely.

Ive just bought all new cooling sys hoses with view to replacing the coolant (add some antifreeze) and thought this would be an ideal time to fit a temp guage. Also where would be the best (cheapest) place to get one.

Since I have had the car, the heater has never worked - i think this may be due to one of the hoses from the heater being kinked, (almost back on itself) therefore stopping water flow to the heater. Hopefully the new hoses will sort that - but I think it may be worth replacing the heater hoses then flushing the system.
Has anyone a reccomendation for a coolant system flushing fluid that i can use?
I appreciate it may find leaks etc but I would ather do the job properly and get all the crud out of the system - and maybe the heater will work!

Not having a temp guage makes me nervous.....
Any advice would be gratefully appreciated

Thanks

Steve

• water temp guage 

  Posted By : William Davies, 05-Oct-2004, 09:02pm

  Hi Steve,
  A 1965 car should have the original 12V dashboard electrics rather than the later 10V olt stabilised system. This has two implications. Firstly, you must make sure tha both gauge and sender are compatible with this setup. Secondly, the 12V system can be very prone to drifting with battery charge levels as it is driven directly off battery voltage. This can mean that at higher engine speeds your gauge will read higher than at idle (because the dynamo is working harder), when in fact the temperature is the same. This has happened to me in the real worls with one of my own Heralds, I spent months worrying about high engine temperatures which were eventually traced to electrical anomalies........ The later voltage stabilised setup is more reliable as the voltage is regulated down to a uniform 10V, so less susceptible to voltage drop at the battery.
  For my money I would fit a capillary type gauge which is a mechanical rather than electrical device. It's just as likely to be badly calibrated as an electrical gauge, but once you are used to what is a normal reading for your car, any deviation will be genuine rather than a fault elsewhere in the system. It's also an opportunity to fit one of those natty dual gauges as beloved by those octagon wearing cars - an oil pressure and water temperature gauge in a single 2" instrument,
  Cheers,
  Bill.