Adding inboard engine gauges

[Shaun]

Gday,
Im wondering how easy or technical it is to add some basic instruments to my 10HP Arona inboard diesel,
maybe a tachometer, & a temp' warning alarm.
Do others with inboards know what temps their raw water cooled engines are supposed to run at?, I heard Yanmars run at 55 deg C for example.
cheers
Shaun

[storm petrel]

Hi Shaun,

I think 50-55 degrees C is about right for a raw water cooled Yanmar. The engine should be hot but not so hot that you can not keep your hand on it.

I thought about adding instruments also but my mechanic told my not to bother - "it will just give you more things to worry about". I ended up just fitting oil pressure and water temp senders and connecting them to warning buzzers and lights. It should be possible to fit a tacho (they just read the AC frequency generated by the alternator) but I have not pursued this either. My mechanic advised me to simple warm it up and cool it down for 5 -10 minutes on idle (fast enough not to rattle too much) and when underway slowly increase the revs as the motor warms up until you start getting black smoke, then back it off a little and run at that rate (about 75% max revs). The Yanmar owner's guide and their service manual for my motor (2GM15) give pretty similar advice. The owner's manual also suggests a short burst of full power just before shutting the motor off.

Cheers,
Mark
Storm Petrel

[Dolphin]

Shaun, I agree with Mark,
Raw water cooled engines must not exceed 80 Deg C as the salt forms a hard crystal that wil not dissolve back into solution. It then leaves a hard salt layer on the cooling gallery walls and the engine will overheat.
Raw water cooled engines have 55 deg C thermostats. That is a problem for diesels because they like to run hot and hard. Fresh water cooled engines can run hot but then the same applies to the heat exchanger that can become encrusted with salt. Hatz D12s have a simple temp switch in the head.
To dissolve the salt use a solution of 1:1 vinegar and water and leave for 24 hrs. If you have salt deposits on your thermostat try dissolving it in a pot of hot solution.
Hatz or BMW marine engines use a splash sump and therefore don't have oil pressure pumps. Incidentally the oil level in the engine is very important because it contributes to engine cooling and gets to places the water can't, ie under the piston and on the cylinder walls. Don't let it get low. Yanmars have, I think, only 0.9 litres of oil in the sump. Hatz (BMW) have 2 litres.
Even large ships run their engines for 1 hour in 10 at full power to clean out all the gunck. They usually cruise at a speed that is economical and minimises vibration and wear. I did my apprenticeship with Aviation and we used to load the diesel generators up on a performance test every 6 months. We'd overload the engines 110% for 15 minutes and there'd be pieces of glowing coke blowing out the exhaust pipe. Petters 2 cylinger diesels were really good at it.
The mechanic that serviced my engine recommended to run the engine for at least 20minutes each time you use it. Don't just start it to get off the mooring and stop it. Use your engine, it will love you for it!
Engines that have internal alternators have tachos connected to them. It is important to know what revs your engine is doing as it is designed to run at a maximum speed for max power and long life. As Mark indicated, if it is blowing black smoke it is overloaded, or the air cleaner is dirty.
"Love that diesel smell"
Greg.

[storm petrel]

Yes, this all makes sense Greg. The only thing I would add is that the crankcase capacity on my Yanmar is 2.5 litres (not 0.9) and clutch case is 0.7 litres. Sound advice about keeping the crankcase oil level at the full mark for best cooling and lubrication.

Cheers,
Mark

[Dolphin]

FIne Mark,
We just had an issue with an old yanmar on Wednesday, don't know the model number, in an Endeavour 26, the owner said it only had 0.9 litre and the dipstick had 0.9l on it too. It seems VERY small. It only took about 1/2 cup and the oil light went out.

Ps The model number is YSE8.

[Shaun]

Thanks Gents for the replies.

Sounds like good advice to run your diesel hard & often, my arona does seem to run better the more I have run it.

The other instruments (tacho etc) sound like their not essential, ....Mark did you install the oil pressure & water temp' sender yourself, could you please give me a quick run down of the process if you did?

cheers

[storm petrel]

Hi Shaun,

Yes I put the sensors in. I bought them from Yanmar. The motor had blanks in the screw-in holes where they fit. It was a pain freeing the blanking plugs but once they were out it was just a matter of a little lock-tight on the threads and screwing the new senders in. They only have one lead which is connected to ground(the engine, -ve in my case) by the sender when the water overheats or the oil pressure drops. So wiring is just a matter of running a single fused wire from active through a globe and buzzer (in parallel with each other if 12V or series of 6V) and to the sender.

It is reassuring to hear the oil pressure buzzer sound and light glow when you turn the ignition on before starting and even more reassuring to hear it go off after the donk starts. I test the light/buzzer for the temp sender from time to time by grounding the terminal at the sender but I have not bothered to remove the sender to test that it works when it heats up(except when just before I put it in). Hopefully it will work.

I am sure gauges would be no more difficult to fit.

Cheers,
mark