Blinking oil light at idle

ALNims · Jul 19, 2015

JacobC22 said:
Good evening everyone,

First, I know that the right answer is "call your dealer" and I'll do that Monday. But, I was hoping to get some thoughts in the interim.

I'm about 5 hours into the breaking-in period of a new Tohatsu 6hp Sail Pro, where I'm running the motor about 3/4 throttle. It's been running great so far, but a little blip popped up tonight. As we were pulling in to a cove to swim and the motor was at idle, the outboard oil light started blinking a little when I slowed to idle. I put it in neutral and it stopped, so I set anchor and checked the oil level. It looked fine, maybe a touch low, so I gave it a tiny top off and we finished our swimming.

After that, it seemed fine. I idled while we picked up the dingy and no light. However, when I was coming up to my buoy it happened again the same way. In gear at idle, it blinked a little. It stopped when I shifted into neutral, and then I shut the motor off. I was losing light, so I couldn't check the oil level again.

I'm going to go back out in the daylight and check the oil level when the motor is cold, but does anyone else have any idea what could be going on? Anything else I should check? Since we're on a buoy, pulling the motor and taking it in for service is a major hassle that I'd like to avoid if it's something easy I can check afloat.

Thanks!

Is your idle set at the right RPM? The oil pump is usually gear driven and engine speed will determine the output of the oil pump.

Ted · Jul 19, 2015

+1 for ALNims response. Idle speed is probably set too low. It's a simple diy adjustment. But since it's a new motor, bring it to the attention of your dealer just in case it's something else.

Chief RA · Jul 19, 2015

+2 idle too low. Chief

Skipper · Jul 19, 2015

Change the engine oil and filter.
You don't know what type and viscosity oil the dealer put in there, nor for how long it's been sitting.
Also, while I don't think break-ins are as necessary as they used to be (check the owners manual), if any particles were going to come loose, they may be in the filter now.

A blinking oil light is nothing to sneeze at. Change the oil using mfg spec, set the idle, and monitor.

If it were my new motor, and since it's only a 50lb outboard, I'd already have it at the dealer to do these things for me, and to test it and repair under warranty if needed.

Skipper · Jul 19, 2015

Skipper said:
Change the engine oil and filter. You don't know what type and viscosity oil the dealer put in there, nor for how long it's been sitting. Also, while I don't think break-ins are as necessary as they used to be (check the owners manual), if any particles were going to come loose, they may be in the filter now. A blinking oil light is nothing to sneeze at. Change the oil using mfg spec, set the idle, and monitor. If it were my new motor, and since it's only a 50lb outboard, I'd already have it at the dealer to do these things for me, and to test it and repair under warranty if needed.

Forgot you're on a buoy. Yeah that's more difficult. Drag the dealer out there!

Chief RA · Jul 19, 2015

Jacob: Do call the dealer and inform him,ask opinion, and get his name. It will be the idle. Chief

centerline · Jul 19, 2015

Chief RA said:
Jacob: Do call the dealer and inform him,ask opinion, and get his name. It will be the idle. Chief

I agree... dont assume its a low idle issue until its confirmed by testing... a new motor is unlikely to have oil pressure problems, but not unheard of... it could even be a faulty sensor and everything else within the engine is just fine... but you will never know until a full and complete test is done.
and the issue will be documented if you have an issue later... just in case the dealer tries blowing smoke at you...

SEMPERAVANTI41 · Aug 19, 2015

I have the same Tohatsu on my dinghy, with only a 15" shaft. The oil pressure light will sometimes blink when at idle especially when in gear. I don't think this is a problem as the oil pressure will normally drop at low rpm. You can easily raise the idle speed with a simple turn of the idle adjustment screw, but if the engine does not stall at idle it sounds like it's set correctly.

oldiesrocker2001 · Aug 25, 2015

Not meaning to hijack this thread;
My Merc 4hp-4str seems on the verge of stalling when I twist the throttle to idle OR attempt to run in gear any lower than the setting for "start". Since I'm usually heading for the ramp/dock at that moment, I'm not looking at the oil light but am guessing the light may be flashing if it's on the verge of stalling.
Is this a simple adjustment under the throttle handle or under the cowl or something that is best done while prepping the motor for the season?

jibes138 · Aug 25, 2015

There should be an idle adjustment screw on the throttle cable at the carburetor. Take off the cover and a simple screwdriver adjustment shouldn't take more than a minute or two.

lillia28 · Sep 5, 2015

It's under warranty, so get it checked,
If the light is out in neutral, but flashes in gear, the extra "drag" of the transmission and prop are lowering the idle speed slightly, so the oil pressure sensor is sensing borderline pressure. Say at 800RPM it puts out 7psi. In gear it drops to 750RPM and 6.5PSI, so the light flickers. Let the dealer decide, but I wouldn't lose sleep over it. Engines to day are built to very tight tolerances. Switching to 10w30 from the spec 5W-20 on my Accord caused all sorts of oil pressure issues, so verify oil level and type.
Theres no load on the engine at idle. as long as the pressure comes up when the engine is turning at working speed, I wouldn't get too rattled. If you can, set the idle speed to spec while in gear. Make sure the prop is clean and clear, no weed or monofiliment slowing it down.
Lou

oldiesrocker2001 · Sep 8, 2015

jibes138 said:
There should be an idle adjustment screw on the throttle cable at the carburetor. Take off the cover and a simple screwdriver adjustment shouldn't take more than a minute or two.

Thanks, Jibes. I'll leave a note under the engine cowl for myself for next year's start-up. We already pulled the boat this year - The lake we sail on looks like the Dead Sea on Life-support :cussing: