Yanmar Temperature Sensor Size

[John T1594]

I would like to install a digital engine temperature gauge with overheat alarm on my ~2000 Yanmar 30GM30F to replace the idiot light. I will have to replace the original on/off temperature sensor with one (Teleflex or other) that is compatible with the digital gauge. Does anyone know the size and thread for the original temperature sensor?

 

[Warren Milberg]

Easy Way...

This may not be responsive, but it worked for me, cost $10, and was installed in a few minutes. I bought a battery operated, digital indoor-outdoor thermometer at Wal-Mart for $10. I threaded the outdoor sensor into the engine compartment and velcro'd the readout device just above my engine panel in the cockpit. I wired the sensor to one of the water pipes at the top of the engine. Bingo, done. I realize this does not provide an accurate temp reading as the sensor is not actually in the fresh water side of the engine, but it does tell you if all is going well, or not well, with the temp of your engine. You don't really need to know the exact temp of the water in your engine,just that it's in the normal operating range.

 

[Benny]

A set of tapping screws.

Looked it up in the engine manual but there is no mention of the thread size I guess they assume you will be using standart yanmar temperature switches. If you can get your hands on a set of thread tapping screws find the one that fits perfectly and read the size. You may also purchase a few machine threaded nuts of approximate size and the one the original switch threads into can give you the size. It's going to be in millimeters.I like Warren's $10 idea but I would rather use the sensor inside the refrigerator to verify the temperature of the perishables.

 

[Fred Ficarra]

John, seems to me it's 3/8" pipe.

But it looks pretty small so it could be 1/4" pipe. It's really easy to find out. Just take the sending unit to Home Depot and match it up. I know it's 'pipe' though. The whole top of these engines are 'pipe'.

 

[Pete]

why not both ?

Why not have both the OEM gauge that is hooked up to the buzzer and install a seperate gauge in addition. Use the water heater connection off the block for the hot water heater put in a 2" nipple and the a "T" with the new sending unit installed in the "T" and then to the hot water heater exchange. There are some good responses in the archives and I installed mine three years ago and has worked flawless. Plus there in a built in redunted system TWO alarms if you will. Check the archives took about 30 minutes to installl sending unit the harder part of the job is to install new gauge and wiring. All in all it was a good 1/2 days worth of work. (also changed the antifreeze while I was opening the cooling system) If i remember correctly it was 1/2 inch size There is a issue with the tread but I found that the npt(national pipe thread) work fine off the engine block. Good Luck with your project ! !

 

[Pete]

another temp gauge

there is a second option you have also and that is to install a exhaust water temp gauge. The idea is that before the engine water temp gets hot enough to overheat the exhaust water temp will get hot first indicating a problem with the cooling system before the closed side of the cooling system get hot.More typical of commercial boats but not a bad idea if you are concerned about the engine running hot.

 

[Fred Ficarra]

Pete, maybe not.

You're talking about raw water getting hot. If a fresh water hose fails, no hot coolant will reach the cold water to heat it up. You'll have no warning. If a fresh water belt fails, no hot water will reach the cold side. The block water will boil in short order. Your boat will look like a steam engine. The charge alarm might sound. But still, you'll have no warning for many possible failures. I wouldn't mess with proven systems. Just make sure they work as designed. And add gauges like we're talking about here if it makes you feel better. But don't rely on just a gauge. They don't work all alone on sailboats. You would have to constantly look at them for any protection. That's even problematic on cars. Most cars use an alert light with gauges.Besides, you say that the cold water will get hotter than the fresh water if there's a failure. How? Raw water gets its' heat from the fresh side. You know that we're talking about a Yanmar, right? Even the exhaust manifold is fresh water cooled.

 

[John T1594]

Follow-up

I contacted the folks at the Mack Boring Yanmar dealer in New Jersey about the thread size question and if there was any other temperature sensor that would fit the 3GM30F and work with a temperature gauge. They wrote back with the following information:"P/N 144626-91570 temperature sender will fit the 3GM30F. It has a 3/8” NPT thread, same as the alarm switch. It has an operational range of approximately 100-250 degrees F."However, according to the Torresen web site, that part is no longer available and has been replaced by P/N 144626-91590. Their price is $40.