Engine Gages and Sending Units

[rt11002003]

Yanmar doesn't provide oil pressure and coolant temp gages with the engine in the R-21 EC. Nor, do they provide optional gages.

I'm planning to install both gages on my tug. The engine already has sending units for oil pressure and coolant temp; they go to the alarm signal devices in the engine control panel.

Obviously, they send electrical impluses. Would those senders power gages, such as those made by Teleflex Morse, in addition to powering the signal devices?

I'd rather not tee off the engine ports and have two separates senders for the same info.

 

[rustednail]

Hi,

I've been thinking of doing the same thing. Would be nice to see pressures rather then lights when things have already gone wrong. I'm afraid that those senders are most likely switches and are either on or off. I think the only way to incoperate an actual gauge would be to tee in some extra senders. I could be wrong though.

An easy test to preform would be to disconnect the wire at the sensor and place a meter from the sense post and ground. Take a measure ment with engine off and one with engine on. Meter should be in OHMs. If meter shows gradient reading, then it will drive a guage. If indication is full closed or full open, then its a switch.

I might get around to doing that test next weekend, but I'm unsure if I will be able to get down to the boat. We're gearing up to sell our home and I have some fixing up to do.

Another consideration: If you did tee in a sensor, then the switch would still drive the alarm, but a guage could give trending if monitered regularily; they're doing simular jobs, but not quite the same.

Best Regards,
Brian

 

[commander bill]

I have the R25 with Yanmar so I have pressure & Temp indication. If you have worked on car engines before you probably know that those sensors could only be switchs. A gage requires an analog sendor. alarms either use the same sendor with some sort of alarm circuit or there is only a pressure or temp switch (which looks much same as a sendor) but the electrical output is either "on" or "off". If all you had was alarms it is likely the manufactor used switches to keep system simple.

You can take a VOM and check output of what you think are sendors to check to see which you have.

 

[rt11002003]

Thanks guys, for the input.

The Yanmar in my Albin 27 AC had a single sending unit for oil pressure and one for coolant temp. Each fed both the alarms and the gages. Those alarms were on/off devices/switches. The gages sensed changes and displayed them on a scale. This means those sensors transmitted varying signal strength.

I think a simple test would be to connect the gages to the sendors on the engine in my tug and see what happens. Maybe risky. 😱

Brian's idea may be best. 😀

commander bill, my recalled experience with analog input was running copper tubing from the engine to the oil pressure gage. I don't recall what I did about temperature. The past is dim and cluttered with many, many projects. Such as, installing an aftermarket heater (American) in a MGA, using it in the winter as a heater and moving it in the summer to use as an additional radiator, VA summers were hot, hot. Heaters were optional on early MGAs.

Gene