The Stovebolt Site Forums The Shop Area Engine Shop Temperature gauge won't work

I have installed two new temperature gauges in my 235 trying to replace the malfunctioning one that came with the truck.
I tested the last in hot water on the stove before installing it and it worked OK albeit very slowly.
Now that it is installed it is a dud too.
What am I missing? I'm stumped.
Any suggestions are appreciated as always.

Loosen the sensor fitting and confirm you have engine coolant at the back of the engine, the sensor could be sitting in an air pocket.

If you have fluid, remove the sensing bulb from the head and stick it in a pan of hot water to retest it...it could have been damaged during installation.

Mike B

is this in the '51? mechanical gauge with the attached sender? sender in the right place?

Bill

Yes, they have the sender attached via copper tubing and come as a complete unit.
The engine is '61 235.
I put it back where the PO had it installed. He said it worked sometimes. There aren't that many choices that I can see.
I read in one post that it could be the use of Teflon tape but, I don't see how that could affect things.
Thanks.

teflon tape is only a problem with electrical senders, which need a good ground - could be an air pocket as Mike says, otherwise I don't see how a mechanical gauge could work "sometimes" unless it's a faulty gauge or maybe the needle is dragging on the glass or gauge face, but assume having tried different gauges that wouldn't always happen

Bill

They're very fickled, the ether can creep out of a pin hole or burn out in a flash. My current one really lags and sometimes doesn't kick on until it reaches operating temp. And it's an expensive auto meter.

Bill, I had to replace my original temp gauge in my '50
several years ago with one of the reproduction ones from
Chevy Duty.
It often sticks at start up and after 15 or 20 minutes it will
pop up to the correct reading as though the needle is
sticking on something. This started a couple of years after
I'd installed it. The needle is not bent and the movement is
free, is it has to be something to do with the internal part
of the movement. I suspect it's just another one of those
crappy parts that was assembled in some back alley in China
with no concern to tolerances and no QC.

Peter there shouldn't be any tefflon tape needed to seat the
bulb, unless it's for the adapter. If you have a '61 235 then
it would need an adapter because the it originally uses a pipe
thread. The adapter allows you to use the sealed bulb type
gauge, which seals by a type of compression seat and nut. If,
as Hollow65 mentioned, you've cracked the bulb installing it,
the ether may have leaked out. That you should have smelled
because it has a very distinctive smell. The younger set
probably aren't familiar with ether, which was a common
smell around doctors offices and hospitals years ago.
How ever, if it is working when you put it in boiling water
then the other most likely possibility is as Mike mentioned,
an air pocket.
I don't quite understand the statement you made earlier, "I
put it back where the PO had it installed." It can only go
in one place, which is at the back of the head on the left
side, with the adapter bushing.

Denny Graham
Sandwich, IL

look at the new ones compared to an original one and it becomes very apparent why they don't work. I installed three new ones. One had the bourdon tube too big. It hit something in the gauge panel, and made the needle stick straight out, another didn't do anything, even another pulled the needle straight down into the face of the gauge and stuck there, it eventually moved, but it wasn't something I was going to pay what ever it was I paid for it. I eventually got an original from Pre-68 Dave, and that is working fine. It seems gauges that actually work are hard to come by. I went through 2 oil pressure gauges before I got one that didn't leak. But since virtually all vendors use the "counterpart" brand. That is what you are going to get. That one fella last week got an oil pressure gauge that is backwards. The best option if you want to spend the money is to send the originals off to someone to rebuild. I don't know of anyone right off hand but they are out there. And I mean the originals, don't send the new ones off to be refurbished, because the new ones are substantially inferior.