Yamaha 2-Stroke Oil Problem

[slicknick8585]

I have a 2003 Yamaha 150 HP 2-stroke (VX150TLRB). I had a problem Sunday with the oil reservoir on the engine running dry with plenty of oil in the reserve reservoir. To fix it, I just poured oil directly into the engine reservoir. However, the engine was run with this reservoir completely empty.

I was going down the lake at WOT and the engine started backing down to near idle speed. I put the motor in neutral as it continued to run and then was able to throttle back up, for approximately 50 feet before it throttled down and died. I turned it off. I am a novice (first boat). I checked the batteries (ok), fuel (ok), spark plugs (ok and tight) and oil (ok in reserve tank)...I was under the impression that the oil in the reserve tank went directly to the engine, I didn't know that another tank was fed from the reserve tank, therefore, didn't check the oil in the tank mounted on engine (unfortunately). I put the cowling back on, started it up and it was running rough, but running. When I put it in gear, it would die. I then started it with about medium throttle in neutral, and it sounded very rough and would die when I put it in neutral to then put into gear. I took the cowling back off and traced the oil line because it sounded like something wasn't getting oiled. Discovered the oil tank on the engine and saw that it was empty. After I finished cussing, I put oil in the tank directly. I started it up in neutral and let it run to try and lube it up. Progressively over the next minute, the engine started sounding much better. Let it idle for 5-10 minutes. Kicked it in gear and off we went.

However, when we stopped some time later the engine wouldn't turn over. Check oil and it was ok. Primed bulb and tried again. Nothing. Waited about 10 minutes and it fired up. Had the same thing happen one other time. This is intermittent, as sometimes it fires right up.

What do I need to check in order to see what damage has occurred to the engine? I don't want to keep running it if I am going to continue to cause more damage.

-Nick

 

[99yam40]

Re: Yamaha 2-Stroke Oil Problem

If motor is locking up, it is not good news, need to have Yamaha tech see what damage has been done
Check compression an all cylinders, to see that rings,pistons, and cylinders are sealing.
look into the cylinders with a bore scope to see if you can see damage
I do not know of a way to check bearings and crank without tearing motor apart
hook up a portable fuel tank with mixed fuel/oil in it and flush the system to make sure you have the mixed fuel all into the system.

clean oil tank and lines,
Test and repair oil system and bleed air out if oil lines.
Make sure oil system is functioning before going back to straight fuel

 

[slicknick8585]

Re: Yamaha 2-Stroke Oil Problem

If motor is locking up, it is not good news, need to have Yamaha tech see what damage has been done
Check compression an all cylinders, to see that rings,pistons, and cylinders are sealing.
look into the cylinders with a bore scope to see if you can see damage
I do not know of a way to check bearings and crank without tearing motor apart
hook up a portable fuel tank with mixed fuel/oil in it and flush the system to make sure you have the mixed fuel all into the system.

clean oil tank and lines,
Test and repair oil system and bleed air out if oil lines.
Make sure oil system is functioning before going back to straight fuel

I'm not sure what you mean by "locking up". The motor doesn't run at say 2000 RPM and then stop immediately, nor does it idle and stop immediately, it was more of a putters out. But since getting it re-oiled, it stopping isn't the problem, it is the intermitten not starting that is the problem (once every 4 tries). It seems the longer it stands, the less likely it is to start up. Also, when you say check compression, I understand the process on how to check it and that it should be +/- 10 on each cylinder, but what would the target number be? Is it possible for them all to read low but still within +/- 10?

Thanks for the help!

 

[99yam40]

Re: Yamaha 2-Stroke Oil Problem

If motor will not turn over , to me that means starter will not turn motor over and is locked up.

If it was making noises that sounded like it was not oiling, that also sounds like knocking or binding up to me.
You will need to do a better job of explaining things I guess if that is what you did not mean.

Take the readings and then post what you get, should normally be over 100, but there are no specs on compression

 

[slicknick8585]

Re: Yamaha 2-Stroke Oil Problem

Results from compression test:

Looking at motor from the stern to the bow...
Top Left = 60
Mid Left = 105
Bottom Left = 70

Top Right = 110
Mid Right = 105
Bottom Right = 105

Reading my Seloc manual, I added several drops of oil directly into the cylinder and re-checked the compression on the Top Left and Bottom Left, getting the same results. Seloc says if this happens "suspect one or more defective rings or a defective piston, but you can also suspect oil seals or reed valves". Is there any further testing that I could do to better narrow down which path to take? Should I still do the mix of fuel/oil to flush the system?

Also, with the cowling off, I can hear a knock but am unable to pinpoint where it is coming from. Is it bad to leave the motor running while it is knocking to try and identify the sound?

 

[99yam40]

Re: Yamaha 2-Stroke Oil Problem

looks like you toasted 2 cylinders and will have to repair or replace the power head.
The knocking sounds like bearings are shot also from lack of oil.

Need to have motor taken apart to see how much damage there is and how much it will cost to fix

 

[slicknick8585]

Re: Yamaha 2-Stroke Oil Problem

Is that something best left to a professional? Do you have a general idea of how much it would cost to repair the powerhead so I can see if the estimate is in the ballpark?

Will the powerhead be further damaged or will other cylinders be damaged if I ran the motor with the 2 bad cylinders?

Thanks for your help!

 

[99yam40]

Re: Yamaha 2-Stroke Oil Problem

Take it to a good Yamaha shop to have it checked out.
If you keep running it it will come apart