Mystery Gauges

[snook91901]

The PO of my boat collected various odds and ends during the years he was planning on fixing her up himself. I am grateful that all of these things came with the boat at purchase (new teak handrails and tiller, ground tackle, replacement fuel tank, spare carb...etc), but some have been a little confusing or not suitable for my boat (set of wooden spreaders not even close to the correct size). Among these things is a rather handsome instrument panel with tach, ammeter, oil pressure and temperature gauges.

Knowing that some sending unit/gauge pairs use different resistance at the sending unit for a given oil pressure/temperature, is there any way to identify an appropriate sending unit for these gauges, or at least to identify the gauges themselves in order to order the appropriate senders?

[jpian0923]

Can you post a pic?

[Dave Neptune]

Worth a try

Snook, are there no names on the gages or panel? If you can identify the "brand" you should be able to find the info on line.
Per jpian post a pic if you can, perhaps someone could identify them.

Dave Neptune

[snook91901]

There is no brand information on the gauges. I'll post a pic soon.

I suppose I could go buy a set of cheap resistors and test the readings on the gauges with simulated resistances from the "sending unit." 33 ohms at 0psi, 230 ohms at 80, for example. That just sounds like more work than I want to do

[snook91901]

Temperature Sender ID / Alternative temperature reading

After deciding to just scrap the old gauges (never could get them to work) I tried to remove the temp sending unit, but she wouldn't budge, even with the breaker bar and penetrating oil. I suppose I could probably put more force on it, but I was wary of damaging the head. Drilling the sending unit out does not seem fun, so now I am left with using it as is and finding the matching gauge.

The resistance at about 70F was around 2.5 K ohms and this decreased to 500 ohms around operating temp. Can anybody help me guess at a gauge brand? I've spent countless hours trying to match these resistances to gauges online to no avail.

Alternatively, is there any other reliable way to keep an eye on engine temp? Other places to install temp sending unit? Surface temp readings? Oil temp readings? Sticking my hand on the block?

[jpian0923]

Did you try heating the unit before removing it? Mine was hard to get out too.

[Marty Levenson]

tee?

Couldn't you leave it as is, and install a tee fitting where the hot water enters or exits the manifold? Then put a new sensor in one side of the tee....?

-Marty

[snook91901]

JPian-
I tried it with a hot engine. I will try with cold or cooling engine next time I'm down there.

Marty-
good idea. Would that water be roughly the same temp as the water going across the original temp sender location? I would imagine if there is a lot of water going through the bypass loop it would give falsely low temperatures.

[jhwelch]

I'd try the T solution too. You don't need to have the T location match the temperature range you get where the current sensor is. You are interested to know if there is some departure from "normal" numbers. Once you have the T installed you will get some experience what those "normal" numbers are and then can watch for overheating.

-Jonathan

[hanleyclifford]

http://www.moyermarine.com/forums/pi...tureid=826Here is one suggestion.

[jpian0923]

or,

http://www.moyermarine.com/cgi-bin/shopper.cgi?search=action&category=GAUG&keywords=all&template=Templates/B000_storebuilder.html

[Marian Claire]

Alternatively, is there any other reliable way to keep an eye on engine temp? Other places to install temp sending unit? Surface temp readings? Oil temp readings? Sticking my hand on the block?
I have my temp sensor in a T where the water exits the manifold as suggested earlier. I also have a simple oven thermometer sitting on the head, the base is wedged between the head and manifold. Both give very consistent reading but the oven therm is about 20 deg higher. Pics in profile A-4 album. Dan S/V Marian Claire

[Jesse Delanoy]

Snook, I had a temp sending gauge that wouldn't budge, too. I wore off all the edges on the hex bezel trying to get it out, until it was perfectly round. I had a new gauge and sending unit ready to install, but just couldn't get the old unit out.

One day, when I'd been working on the engine and it was nice and hot, I took my biggest vice grip, clamped it on the sending unit as tightly as I could, and gave it a couple of whacks with a rubber mallet (remember -- righty-tighty, lefty loosey!!!). That loosened it, and it came out like a dream.

If you still have hex edges on yours, you should be able to do the same thing with a socket wrench. Just start tapping on the wrench handle, gradually increasing the force. It should work.

[snook91901]

I'll try again to remove the old sending unit, although it is a shame because it works fine.

My concern with installing a sending unit in an alternative location is that the engine I am working with sat out in the rain for years before I began resuscitating her. I've no idea if the current normal operating temp is overheating or not. Also, I have pretty low flow through the cooling system so I need a way to check if it is sufficient or not. Maybe I'll buy an infrared thermometer and measure the engine surface temp directly in a few spots to get an idea that she's not overheating, then I'll install a sending unit between the thermostat housing and the manifold.

Can anybody give me an idea how hot the surface of the engine should be in a few locations? I've read on a few threads that the head temps can vary greatly depending on the flow around the head and this isn't as much as a concern as block temps. Is this true?

[roadnsky]

Can anybody give me an idea how hot the surface of the engine should be in a few locations? I've read on a few threads that the head temps can vary greatly depending on the flow around the head and this isn't as much as a concern as block temps. Is this true?

At fully warmed up running temp, my cockpit Temp Gauge reading at 170°...
my laser temp readings of the head and block vary from 140° to 200°

The UHS and around the plugs are always the hotter readings.