Water pump pulley question

[Jack Innes]

Originally Posted by Lynn Eades

BTW the flathead block has an entirely separate system for each bank, that is only connected by the radiator and fan belts.
That means if it wasn't for the water mixing in the radiator,the water in each bank would never meet.

This can lead to undetected problems if the water circulation stops on the side without the heat sender. That bank of cylinders can become overheated before the temp. indicator shows trouble. The bottom line is not to trust the indicator if you suspect something is not right. Later flatheads had a sender on each side. Worth noting - while they look alike, the dual senders are not the same - the second one is a switch that, on overheating, closes & sends the indicator to the full hot reading.

[Lynn Eades]

Do you mean the single terminal one is a switch? I understand they are wired in series- single teminal to the second sender, and the other terminal of that one goes to the guage.
If that is the case, then are there two types of single terminal ones? a switch type, and a sender type? (a sender type for motors with only one sender)

[Jack Innes]

Originally Posted by Lynn Eades

Do you mean the single terminal one is a switch? I understand they are wired in series- single teminal to the second sender, and the other terminal of that one goes to the guage.
If that is the case, then are there two types of single terminal ones? a switch type, and a sender type? (a sender type for motors with only one sender)

Lynn, You are correct, there are single terminal senders that are either a switch or a rheostat type. The switch type is also used on vehicles with an "idiot light" on the dash. The two senders are actually wired in parallel. Either one will take the power to ground when activated. The rheostat does it progressively while the second sender is either on or off. The two terminal type have one terminal with two mounting points to create a connection to the second sender. The 2 sender system actually carried over on some later Y-block engines. I have it in a US built 54 Ford.

[Nigel Watson]

Knew this was the place to ask the questions. I should write a book about you guys!! Rob thanks for initial explanation. I had wondered if the end of the shaft had been flared after the pulley was on..but no.
The whole unit has just been overhauled so am happy all is ok, touch wood! The shaft is also turning freely with no catching or movement. So a wee chap on with loctite will be tried.

Jack if I fit a temp sender to both sides can one go to the gauge and another to a light (to save having two gauges)? Or should I just put a length of flexible hose from the radiator overflow down the driver's neck? !!!

Thanks again everyone.

[Jack Innes]

Jack if I fit a temp sender to both sides can one go to the gauge and another to a light (to save having two gauges)? Or should I just put a length of flexible hose from the radiator overflow down the driver's neck? !!!

Thanks again everyone.

Nigel, The 2 sender set up does not have 2 gauges. The left sender is a rheostat that operates the gauge in the normal way. The right sender is a on/off switch that, on overheating, will send the gauge to the full hot reading which will indicate trouble. In normal operation the right sender remains open & does nothing & the left one tells you the operating temperature of your engine.

Your overflow extension might get a more immediate reaction if the driver sat on it!