Options for adding gauges to Yanmar 3GM30F

[dmksails]

My Yanmar 3GM30F only has idiot lights for the oil and temp indicators. I would like to add a gauge to this so I can tell if the engine is getting hot before the buzzer goes off. Can anyone suggest a solution for getting oil and /or water temps?

[Spot]

My thoughts go to appropriately-sized T-fittings, or blocks drilled and tapped in a t-formation, and a second electric sensor going to a matching gauge for each water temp and oil pressure.

[Wotname]

Presumably you are wanting a water temperature gauge and a oil pressure gauge. Very few fit an oil temperature gauge and they are really not relevant for small marine diesels.

Most car (auto) gauges are suitable for a 3GM30F however Yanmar uses BSP threads on the engine and North America uses NPT threads for the the gauge sensors.

BSP threaded sensors are available from the better gauge manufacturers. If you elect to use NPT threaded sensors and if you are handy (and careful), the existing BSP female threads on the engine can be re-tapped to NPT.

On the smaller sizes, I have found NPT male threads will fit into BSP female threads but it needs a good thread sealant and while I have done it, I don't recommend it.

[GordMay]

Idiot lights are supplied from switches, whereas gauges are controlled by (variable resistance) senders.
Get a set of gauges, with matching senders.
See "Basic Engine Gauge Theory and Testing"
➥ https://www.cruisersforum.com/forums....html#post2597

[Lazy Jack 32]

My boat has a Yanmar 4JH, but I imagine this will work for you: this past summer my mechanical buddy and I bought gauges from a car parts shop and ordered adapters from a Catalina sailboat parts supplier (https://www.catalinadirect.com/) so we could hook them to the engine. We had to drill a couple of holes near the ignition panel for the gauges, but it was quick work and turned out successfully.

[tkeithlu]

Ditto on bunches above. As Gord May says, the senders in question are all variable resistances, so you put 12vDC on one side, and measure the voltage on the other with a little potentiometer, otherwise known as a gauge. Very simple indeed. They are available cheap from automobile parts stores (and Amazon) because car buffs don't like idiot lights, either. The only problem is the threads Wotname so capably deals with. The fact that the cheap gauge is likely to be way out of calibration does not really matter, because in both cases you are looking for change, not an absolute number. Assuming analog gauges (digital are available, too), either turn the gauge so that the normal value (warmed up, doing fine) is straight up or mark the panel at the point you expect to see. Then you don't have to think "Is that normal?" Just looking at them says all is well or something is not.

[Scubaseas]

Oil pressure senders can be had with both pressure and warning light.
Water temp sensors less so but they are out there. If not a tee fitting would work. Or one of the zinc holes. Really anyplace in the cooling jacket would work OK.
An oil temperature gauge is pretty useless on a boat but you can use the drain plug hole for one.
You might consider adding an exhaust temperature warning sender which will let you know before you start to over heat if you have a raw water flow problem. This is a thermo sensor that straps to the outside of the exhaust hose near and down stream of the mixing elbow.

[james pask]

I have fitted water temp and voltage gauges to a Volvo Penta, the threads issue is the same - I bought low cost car gauges + put an inline adaptor into the hot water supply hose to the calorifier - which is threaded for the 1/8th NPT sensor, works a treat and you only need to be made aware of a rising change rathar than absolute temp reading. The voltage is just hooked into the starter battery so i can see the alternator is charging . V.simple and inexpensive peace of mind.

[stormalong]

Originally Posted by tkeithlu

Ditto on bunches above. As Gord May says, the senders in question are all variable resistances, so you put 12vDC on one side, and measure the voltage on the other with a little potentiometer, otherwise known as a gauge. Very simple indeed. They are available cheap from automobile parts stores (and Amazon) because car buffs don't like idiot lights, either. The only problem is the threads Wotname so capably deals with. The fact that the cheap gauge is likely to be way out of calibration does not really matter, because in both cases you are looking for change, not an absolute number. Assuming analog gauges (digital are available, too), either turn the gauge so that the normal value (warmed up, doing fine) is straight up or mark the panel at the point you expect to see. Then you don't have to think "Is that normal?" Just looking at them says all is well or something is not.

Right answer wrong terminology. The potentiometer is the variable resistor in the pressure sensor. The temperature sensor is a thermister. The gauges are voltmeters.

[Cheechako]

It's very doable. Some Yanmar panels had gauges. At least temperature, not sure about oil pressure. My earlier 30 HP Yanmar (3QM?) had a temp gauge and a buzzer. It was just a Tee at the engine block.

Another handy option is a cheap "snap disc" thermostat put onto the exhaust elbow with a hose clamp. With a buzzer it will alarm you if you have lost an impellor or have a blocked sea water inlet.... probably before you notice an engine temp rise.

[cottonsail]

Check out Marshall instruments in Ca. Great quality at reasonable prices. Additionally they have a good selection of mechanical instruments.

[Spot]

I would do something like this picture so new sensors and gauges are added and 'idiot lights' are kept. I am blessed with a machine shop at work where the guys do not voice their displeasure at my home projects and I try to compensate with extra effort when they need help with prints or CNC files and an occasional box of doughnuts at their break table.
The Catalina link would get you there too for gauges and replacement senders.
BSP to NPT adapters can be had as well.
The possibilities are amazing...
PS: Wotname's tip on the threads +1

[B25Matt]

Are you any good at electronics DIY. I added 5 temperatures, 6 a/d channels and a pressure transducer to my 3QM30 and send the data to SignalK. I used an Arduino to do so, optionally the Arduino can host a web interface to display data.

[jacktheflyer]

Originally Posted by B25Matt

Are you any good at electronics DIY. I added 5 temperatures, 6 a/d channels and a pressure transducer to my 3QM30 and send the data to SignalK. I used an Arduino to do so, optionally the Arduino can host a web interface to display data.

I'd be very interested in this. Have you posted your project anywhere?

[Wotname]

Originally Posted by stormalong

Right answer wrong terminology. The potentiometer is the variable resistor in the pressure sensor. The temperature sensor is a thermister. The gauges are voltmeters.

Well if we are going to pedantic, let's do it properly - .

Considering 'good old run of the mill' analogue gauges.

Both the temperature sensor and the pressure sensor varies their respective resistance of the unit with the corresponding changes of temperature and pressure.

These changes in the resistance of the sensors causes changes in the current flowing through the sensor. The gauge responds to this changing current by measuring the change in the magnetic field of the meter movement.

So it is more accurate to say the gauges are magnetic field gauges but loosely speaking they are amp-meters because without the current flowing through the meter movement, they would not deflect the pointer.

Analogue voltmeters are really only a special case of amp meter - one that has a high value series resistance in the meter movement.

Okay, now back to regular programming .