All engines: Prolonged no-load operation of the engine may cause it to blue/gray smoke at low rpm with an associated increase in oil consumption. For every 3-5 hours low load operation (trolling) or no load operation (running the fridge or charging batteries) should be countered by 10-20 minutes near maximum continuous rated rpm.
http://www.yanmarhelp.com/operate.htm
What is the 1GM10 really rated at, seems we call it an 8hp or a 9hp?
The owners manual says this:
Continuous rating at 3400 rpm = 8hp
One hour rating at 3600 rpm = 9hp
So now whe know.
An engine with less than 400 hours on the clock has been used as a back up 12 volt charge unit and recently as a 220 volt generator power source. When just providing 12 volt power the engine ran at around 1800 rpm ,there is no rev counter, so thats an estimate. Since the AC side was hooked up (thanks George) the motor has had to be run faster and I would estimate some 3000 rpm right now?
This past summer the engine has been run to warm it up only, so very little load, no on board AC fan heaters required of course. The engine has been using far too much oil (marine grade) and blue smoke has been coming from the exhaust outlet. Its known that the engine is in good condition and a new set of piston rings ( Yanmar's own quality) were fitted after sea water finding its way past the anti siphon system.
A new but very expensive Vetus anti siphon was fitted and there has been no bother since, the cost seems to be worth the expense?
Note, the open vent hole must be above the level of the outside water, the instructions that come with the Vetus siphon breaker are very clear to read.
With winters arrival in Cape Town, the boats heaters have been in action, with two 1000 watt fan heaters and two 260 watt heater panels, a load of around 16 amps can be seen when the Yanmar GM10 is running, there is both a volt and an amp meter fitted,they are recomended. When the hot water geyser kicks in, the amps jump to around 20 on the meter. The 12 volt charge system is adding a further 20 amps load, this helps the batteries of course. In this case I have all the cabin lights on to raise the load on the alternator and add to the load on the Yanmar.
With such a high load on the Yanmar, which is rated at about 8 to 9 hp, the exhaust now burns smoke free and all that can be seen is clean water and light steam as the warm water hits the cold air, problem solved!
Clean water and clean air is just about all that can be seen exiting the exhaust pipe now.
Pictures of the Yanmar GM10 and Vetus siphon break are by R McBride, the camera was a Canon G11 on a standard setting.
How hard can that be? well we nearly stripped the motor to see what was wrong!
Roy
