no need for oil under 1800 RPM???

[bob johnson]

buddy at work has an 1987 johnson 140 hp.

he says he read somewere along the line that OMC stated that it is ok to run the motor under 1800 rpm with out oil.

he said in case you ran out of oil out away from the dock you could still run the motor back, if you kept the rpms under 1800..

says that they say that the gas alone is lubricant enough for the motor at those low rpms

says that came from OMC

does that sound right???

thanks

bob

 

[iwombat]

Re: no need for oil under 1800 RPM???

No.

Even the OMS/VRO systems lubricate at AT LEAST 100:1 at idle. Gas is a solvent, not a lubricant - especially when loaded with 10% ethanol.

If you run your engine w/o oil at low RPMs to get back to the dock, that's probably as far as you're going to get.

 

[HybridMX6]

Re: no need for oil under 1800 RPM???

Yeah, just carry an extra bottle on the boat. Much cheaper then an engine overhaul. Heck, even a tow from SeaTow is cheaper than an overhaul.

 

[bob johnson]

Re: no need for oil under 1800 RPM???

thats how I looked at raw gas...a solvent not a lubricant...

but with motors i am learnign more and more...as i rebuild this 70 HP I am in the middle of.

bob

 

[R.Johnson]

Re: no need for oil under 1800 RPM???

I remember the discussion came up at service school at the Johnson plant. The instructor talked about some tests done to failure running the engine on raw gas at idle speed. I just remember him saying that it ran for quite a long time. He sure did'nt recommend doing that. In an emergency, I suppose you could do that to get back to the dock. As far as the engine running on no oil, how do you know that until the engine goes bang?

 

[tashasdaddy]

Re: no need for oil under 1800 RPM???

it will run longer with no oil, than it will with no water.

 

[bob johnson]

Re: no need for oil under 1800 RPM???

so its better than a poke in the eye with a sharp stick?

I guess the catch is really HOW FAR IS THE DOCK??

thanks guys

I told him

now he is determined to find it in his literature

bob

 

[Dhadley]

Re: no need for oil under 1800 RPM???

We were involved in that test back in the day. The point was that if you knew you had no oil, how long would the motor run at 1100-1200 rpm. The rpm range was based on the fact that the motor would still be charging the battery(s) and you would be making some progress.

Personally I didn't think it would last very long but it did. We stopped the test at a few hours. The engineers stopped their test at something like 24 hours. No motor involved in any of those tests were hurt at all and all were taken apart.

Not sure how long it would last at 1800 though.

 

[jeff_smith_0423]

Re: no need for oil under 1800 RPM???

I sure wouldn't do it with a carbed non-direct injected outboard, but the Etec's now can operate for five hours at reduced output with no oil. Not sure how long this feature has been built into their CPU's. I would suspect that the combination of e-tec's enhanced tolerances as well as the oil being directly injected at strategically placed lubrication points instead of being mixed into the fuel helps.

 

[kenmyfam]

Re: no need for oil under 1800 RPM???

Don't think I would ever leave myself in a position to have to try it !!!!

 

[Mas]

Re: no need for oil under 1800 RPM???

Is this where the 100:1 came from?

MAS

 

[mhg]

Re: no need for oil under 1800 RPM???

just another reason for premix
if I have gas I have oil

 

[bob johnson]

Re: no need for oil under 1800 RPM???

well he brought his johnson 120/140 owners manual in today and on page 6 it says:

"NO OIL FLOW: the horn will sound continuous short pulses if there is no oil flow from the VRO pump to the engine.
Do not attempt to operate the motor above 1500 RPM. See your dealer for service.

NOTE: when the warning horn sound indicates no oil flow from the VRO pump, operation of the motor above 1500 RPM can result in serious engine damage. If it is necessary to operate above 1500 RPM to return to port, lubricant must be mixed with the gasloine at 50;1 fuel/oil ratio."

hmmmm

good to know


bob

 

[Dhadley]

Re: no need for oil under 1800 RPM???

Is this where the 100:1 came from?

MAS

Kind of -- when OMC was coming out with the old Economixer they wanted the tests. Those findings led to the theory behind the Variable Ratio Oiling where there was very little oil at idle and it slowly kicked in to 50:1. In reality there wasn't any advantage to the (about) 150:1 at idle.

Remember all this was in the carb days.