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Thanks to all in advance . Can someone supply a picture of the heat sensor position on a 239 Flathead 8 ? I'm new with this and understand there are Two...two thermostats and 2 waterpumps. I assume My motor is running within temp limits as the stock gauge only gets a bit over center when warm. Also...how to install a mechanical gauge to verify temp as being the truck is 70 years old and has original wiring, I'm not sure if anything is accurate. Also mechanical oil pressure. (the original shows over 30psi) AND...is there a shop manual I can get with pictures/diagrams of wiring/cooling/whatever.
Your temperature senders are located on the top of the heads. They're kind of hard to miss. There's wires coming off of them.
The water jackets are separate on either sides of the block. That's why there's two senders and two water pumps, two thermostats, etc. If you want to install aftermarket gauges, you'll need two of them, one in each head where the current senders are.
You should also note that these and your other gauges DO NOT operate off of ohms/resistance model most of us are familiar with, but the King-Seeley principle.
Both sending units are located in their respective head:
If you look at the diagram above, you can use the single-terminal stock sensor to run the dash gauge, and put a mechanical gauge in the other head. The two halves of the cooling system mix together in the upper radiator tank, there is usually a 5 10° difference with the passenger side running warmer.
You can tap the oil system by adding a Tee in the line that goes to the oil filter.
Well...they were right where You guys said they'd be. Now...if I put a mechanical gauge on the passenger side...what do I do with the existing wires? Also what is this pipe for on the passenger side?? (just above 2nd cylinder from the left) Also...by removing the existing sensor....do they get stuck as bad as head bolts on a flathead?
There are two sensor types. The single terminal sending unit is the one that regulates the gauge position. The two terminal one is the one that simply triggers on overheat. I would leave the single terminal sending unit installed where it is and have that connect directly through the gauge by connecting the two wires that were previously on the two wires unit. You can remove the two wire unit and plug in the mechanical unit of choice.
ok....I need a better explanation of where/what to do with the two wires off the two wire unit. Do they go to ground? Connect to the single wire unit? Where would one connect them specificaly ?
Unconnect the two wires from the two post sending unit. Connect those same two wires and together as if a single wire broke. This would have the equivelence of one unsevered wire running from the single post sending unit to the firewall (and on to the gauge).
