Temp Gauge trouble. 42 1 1/2 ton V8

[BouncinBetty]

After fitting replacement second hand instrument panel and new sender unit plus reducer because running 12 Volt my gauge goes up hard against H soon after start up and stays there even though that the previous capillary type gauge showed no overheating .

Any ideas welcome.

Swampy

[Drbrown]

Sounds like something is grounding-out to give you a constant "H" indication. My '47, which has two senders wired in-series, was going to "H" during warm-up but would eventually settle-down to a proper reading after warm-up. There was no over heating and both stats were new. I by-passed the two-terminal sender and the system now works fine. (I have a mechanical type temp gauge on the other side of the engine)

[Graeme / New Zealand]

check the system over

[BouncinBetty]

Hi Graeme, can not seem to blow up your thumbnail without it going fuzy , computers my very weak point.

[bobwellsnoveltyshop]

Hi, You might want to go back and check the voltage on the gauge, it should have 6-8 volts on the voltage side to ground if the reducer is hooked up right, also if you used a new sender a lot of the new reproduction ones are in question as they are not the best as the original ones, also make sure the sender is grounded good, sometimes some use a sealant and prevents good grounding.
BILL WELLS

[Graeme / New Zealand]

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Originally Posted by BouncinBetty

Hi Graeme, can not seem to blow up your thumbnail without it going fuzy , computers my very weak point.

sorry I scanned this ages ago to another computer. When I transferred it to the laptop I now use it is a smaller resolution. I can't copy again because the new machine is not compatible with the old scanner.

Anyone got access to the red book "ford v8 service bulletins 1941 -48 complete" and can scan it to an attachment for BouncinBetty? It's on page 264.

thanks

GB

[BouncinBetty]

Thanks for help fellas.

[41panelmark]

Nice old truck BB!!!

[FireEngineMike]

This thread from 2015 might help:
http://www.fordbarn.com/forum/showth...g+unit+testing

[BouncinBetty]

Bang on that link, I checked out supply 6 volt to gauge and checked earthing, seems to work during warm up so a fitment of the switch type sender that at the moment is missing may do the trick.

Thanks for all the work.

[scooder]

Stock Ford temp gauges read hot "H" at rest, with the ignition off. When you start up, it should go to "C" and then able up to half way. Does yours rest at "H" when off?
The two sender system has one normal type sender and one switch type that when that head gets to hot it opens the circuit, and sends the needle to "H". You can run this setup with the switch sender out of the equation. Just join the two wires that went to the twin terminal switch sender together, and it works like a single sender type.
Can't see how fitting a switch (2 terminal) sender would impact on your odd gauge readings?
Something ain't right.
Martin.

[Ross F-1]

Here's a quick and easy test from the factory manual. Instead of using a variable resistor and all that, just use a "C" or "D" cell battery connected across the gauge head's terminals (with the other wires disconnected). You should get a half-scale reading after it stabilizes.