Yamaha S250TXRX (1999 OX66 250) using 2x oil it should be...

[SBSYNCRO]

Hello all,

I posted this original message a few days ago on another forum for Yamaha motors, but it was suggested that I post it here on this forum as well. Thanks in advance for your help!
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This is a new boat to me, and I've been going through all the fuel system components (low pressure side) and resolved a previous problem with rough running and cut-out at WOT by replacing all the LP fuel pumps, cleaning and replacing the VST tank and filter, replacing all the fuel filters, etc. I also had my mechanic check for trouble codes being generated while in a test tank (none) and use Yamaha test harnesses to adjust TPS and to test O2 sensor after cleaning it and the dip tube. He also put in a new set of NGK plugs, recommending one heat range higher. He also found that the oil control rod linkage clip had been broken and then re-inserted in a "jerry rig" fashion causing it to "oil at double what it should" at idle. It was repaired with a new clip and re-adjusted. This cleared up a very smoky and rough idle problem as well.

The motor idles too high - around 900 to 1,100 even when warm, but according to mechanic, sensors are all within spec, TPS voltage/setting is correct. Taking his word for it, I should just be able to adjust the idle per the manual section 3-6.


All seemed to be running well, and we took her on her first "big" trip - a 90 mile round trip to our local islands and back. The ride out was rough, but we managed about 15 to 20 knots most of the way, turning about 4200 to 4600 rpms, IIRC and burning about 12 gph to 15 gph.

On the way home we made very good speed - about 22 to 26 kts turning about 4600 to 4900 rpms and burning about 13 gph to 18 gph.

My partner was driving and I was relaxing with a beer when I heard the engine alarm go off. I jumped up, looked at the gauge and saw both triangles blinking over the red "window" and yellow "oil can" icons. "SHUT IT OFF!" I yelled, knowing that this meant the main oil tank was empty and the reserve tank was low! Sure enough, even though it was absolutely full when we started, the remote tank was EMPTY (I admonished my partner about watching the gauges while underway!). We had burned about 50 gallons at this point according to the flo scan, which would mean about 25:1 gas to oil ratio (even more since the remote tank was 1/2 empty).

Luckily we had a couple of quarts on board to top it up so we made it back home the remaining 10 miles or so.

The next day, I popped the cover to check and see if the oil control rod had come loose or there was a problem with the clip. I didn't see anything obvious.

Based on my research here on the forum, I'm planning to run through the following test protocol to see what is going on - can you tell me if I am on the right track?

1. Pull the plugs and see if #5 & #6 are excessively fouled, indicating a leaky oil pump shaft seal (I assume #5 & #6 are the bottom-most cylinders?)

2. Drain engine oil tank, check water trap. Strain oil in painter's filter & look for suspended "goo", gel, or emulsion that could be fouling the oil pump (if found, remove, clean & reinstall both engine and remote oil tank).

3. Check tach/alarm operation and transfer rate by turning on key and timing out 180 seconds to make sure I get: audible alarm, 3 blinking triangles, remote tank just above 1/2 full.

4. Check oil control linkage and ensure proper gap (.005-.04.) and make sure it is not bent (either of these would indicate a failure on the part of my mechanic, since I was billed for them to conduct this step)

5. Adjust idle

6. (???) Should I hit the engine with some Seafoam "deep creep" and let it sit over-night, then run it on muffs to clear out carbon deposits? I do not know the status of the engine, as I only have about 10-20 hours of run time on it since buying the boat.

Am I missing anything here? Part of my problem is that I have concerns about the mechanic's competence, but they have the test equipment and I do not, so I am taking their word for the sensors all being in spec

Thanks in advance - at $30 a gallon for Yamalube, it gets REAL expensive at 20:1 ratios, not to mention the fouling of the plugs and OX sensor.

[SBSYNCRO]

Update to this issue a couple of days later:

1. Pull the plugs and see if #5 & #6 are excessively fouled, indicating a leaky oil pump shaft seal (I assume #5 & #6 are the bottom-most cylinders?)

Plugs have maybe 10 hours on them. They were clean but oily. Don't know what "normal" should look like but they did not seem fouled at all. Bottom two plugs were perhaps a bit more oily than the other four but not dramatically so.

2. Drain engine oil tank, check water trap. Strain oil in painter's filter & look for suspended "goo", gel, or emulsion that could be fouling the oil pump (if found, remove, clean & reinstall both engine and remote oil tank).

Engine tank was clean, clean, clean and oil drained out didn't have any discernible foreign material at all. Water trap was clean except for maybe 1cc or less of what looked like dirty water. Much less than 1/4 teaspoon.

3. Check tach/alarm operation and transfer rate by turning on key and timing out 180 seconds to make sure I get: audible alarm, 3 blinking triangles, remote tank just above 1/2 full.

Worked exactly as it should. Alarm cut off at 2:25 and transfer pump stopped at 3:00. Tank was just above 1/2 full. Emergency switch operated transfer pump after it shut off as well.

4. Check oil control linkage and ensure proper gap (.005-.04.) and make sure it is not bent (either of these would indicate a failure on the part of my mechanic, since I was billed for them to conduct this step)

Control linkage has what appears to be normal bend (see pix) and operating properly. I disconnected the throttle cable from the lever on the starboard side and flipped it open and closed a few times. Then I checked clearance at control rod to stop. It was like 1/8"! I unclipped the top clip and rotated the rod 5 complete revolutions before the gap closed completely. Then just to double check, I backed it off again and the gap stayed closed. :-( I went back and forth with the adjustment until I got it to where it was one full revolution tighter than it was before I started, which doesn't seem like enough to be causing the oiling problems.

I did notice that there is a fair amount of play in the black lever to which the upper end of the control rod mounts. It is pretty sloppy on it's shaft, which allows the oiling linkage to deflect back and forth while the throttle is held closed. This play is enough to cause about 1/16" to 1/8" of gap where it should be .005" against the stop if I hold the throttle closed with one hand and push the oil rod with the other.

Could this slop be causing my oiling problem? If I'm not mistaken, my mechanic replaced this black lever (in picture #4 above) so the shaft might be worn(?) which appears to be the shaft for the throttle ****erfly as well..

Where should I go next?

I'm going to sea trial it tomorrow to see how the oil consumption is.

[SBSYNCRO]

[SBSYNCRO]

OK, I made some progress! After hitting the engine hard with Deep Creep and letting it sit over night, (along with the other procedures I mentioned) I took it out today for a trial run. It ran GREAT! The idle was purring at 650 to 750 after warmed up, and the running was smoother than it has been in a while, and the fuel consumption was slightly better (12 gph at 4700 versus about 14 gph previously).

My theory is that the Deep Creep treatment cleaned out the deposits on the O2 sensor caused by the over-oiling.

I only went through 15 gallons of gas today, and it *looks* like I used about 1/3 of the amount of oil in the tank, so it would seem that the oil consumption is still excessive.

At this point I'd have to attribute it to either the slop in the oil control linkage (?) or leakage of the oil pump shaft seal...

But at least I've isolated and determined the cause of the high idle (engine/sensor fouling), and know that I don't need to manually adjust it - instead it is clearly a sensor being fouled (likely the O2 sensor). Progress!

[nikole95]

My theory is that the Deep Creep treatment cleaned out the deposits on the O2 sensor caused by the over-oiling.


______________________
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[rodbolt17]

ok
you need to get the white plastic oil control arm clip and the oil control rod lock nut that is missing.
threads on before th clip.
to CORRECTLY adjust the oil control arm you MUST have the throttles FULLY closed not just at idle position.
two ways to do this but the easiest is to unclip the lower two shutters from the throttle linkage.
once the shutter that controls the pump rod is completly closed then adjust the clip at the oil pump arm to obtain a .005-.020 gap.
its not uncommon at all to cut off the first 5 threads or so to make this adjustment.

now the O2 sensor.
it operates throughout the ENTIRE RPM range.
there are NO troubles codes associated with the O2 sensor.
unplug it and fuel is fixed rich at low speed and lean above 4000 RPM.
DO NOT run above 4000 RPM with a bad or dissconected O2 sensor.

now the fast idle.
this engine when cold will display a code 33 on the diagnostic test lamp, once the thermosensor tells the ECU the engine is 113*F the idle will drop and the code will shift to 1(normal).
if anyother code is displayed idle will stay at 1100 and timing is fixed at 7* BTDC at low speeds.
depending on what failed top speed may or may not be reached.
but the O2 sensor is NOT monitored for any failures or even a dissconect as far as codes or engine speeds go.

I will reiterate, the O2 sensor wont set any trouble codes nor will it increase the amount of oil injected by the pump.
oil injection volume
on that OX66 is a matter of pump arm position and engine speed.
ALL the oil is mixed at the VST and sprayed into the intake via the fuel injectors.

any other questions ?

[SBSYNCRO]

ok
you need to get the white plastic oil control arm clip and the oil control rod lock nut that is missing.
threads on before th clip.

To replace the black clip on the oil pump end of the rod?

now the O2 sensor.
it operates throughout the ENTIRE RPM range.
there are NO troubles codes associated with the O2 sensor.
unplug it and fuel is fixed rich at low speed and lean above 4000 RPM.
DO NOT run above 4000 RPM with a bad or dissconected O2 sensor.

understood. Does it make sense that the high idle prior to de-gunking (and subsequent smooth running and lower idle) was a result of the treatment improving the operation of the ox sensor? When the mechanic cleaned it before, it idled normal and ran well for about 5-10 hours and then began idling high and running a bit rougher (related to over-oiling)...

now the fast idle.
this engine when cold will display a code 33 on the diagnostic test lamp, once the thermosensor tells the ECU the engine is 113*F the idle will drop and the code will shift to 1(normal).
if anyother code is displayed idle will stay at 1100 and timing is fixed at 7* BTDC at low speeds.
depending on what failed top speed may or may not be reached.
but the O2 sensor is NOT monitored for any failures or even a dissconect as far as codes or engine speeds go.

According to mechanic, all codes are normal. I don't yet have a winky (though it is clear I need one!). If the Ox sensor is fouled, the engine won't revert to 1100 rpm and 7* BTDC? What else would cause this change in engine behavior when all I did was wipe the plugs with a paper towel (and check gap - all good) then douche the piston tops and intake ports with Deep Creep overnight?

I will reiterate, the O2 sensor wont set any trouble codes nor will it increase the amount of oil injected by the pump.
oil injection volume
on that OX66 is a matter of pump arm position and engine speed.
ALL the oil is mixed at the VST and sprayed into the intake via the fuel injectors.

any other questions ?

Could excessive play in the upper clip on the oil control rod cause it to double oil consumption?

Also, should I check the volume output of thenoil pump? Is there a way to test if the oil pump shaft seal is leaking into the crankcase? (will volume output test tell me this?

Thanks again, Rodbolt!!

-Brent

[rodbolt17]

yes that black clip, needs to be white AND you need the lock nut thats missing.
over oil cannot and will not cause a high idle.
the O2 sensor can cause a poor idle but NOT a high idle.
there are NO codes NO idle speeds set NO defaults for ANY O2 sensor issues even if its unplugged.
there is an oil output test, however I prefer a consumption test.
that seal,if leaking is easy to change.

[SBSYNCRO]

yes that black clip, needs to be white AND you need the lock nut thats missing.

Roger that! Part number 6H1-41237-00-00 ?

over oil cannot and will not cause a high idle.
the O2 sensor can cause a poor idle but NOT a high idle.
there are NO codes NO idle speeds set NO defaults for ANY O2 sensor issues even if its unplugged.

Makes sense - I understand now. What I don't understand is why the idle performance would improve with nothing more than a "deep creep" treatment. I guess I have to keep scratching my head and looking for answers or not worry about it until I figure out this oil consumption problem.

there is an oil output test, however I prefer a consumption test.
that seal,if leaking is easy to change.

Can you tell me how to find the procedure and specs for the consumption test? Or are you just talking about taking her out, burning 50 gallons of gas and making sure she only burns one gallon of oil?

Is changing the seal is as simple as pulling apart the oil pump (which I'll assume is self-explanatory) and replacing the O-rings I see in the parts schematic parts #19 and #2?

[rodbolt17]

you really cant get a decent oil consumption by simply running it as its a variable ratio system,oil amount is strictly controled by throttle angle and engine speed.
has nothing to do with fuel burn.
the output test is in the service manual.
however the output test requires running on a premix and wont show a leaking shaft seal.
typically the output test is done at 1500 RPM with the pump arm at the idle position and then at the WOT position at 1500 RPM.
typically I use a piece of clear tubing marked for how many CC's I expect to consume(input equals output) shoved into the pump intake pipe.
myself I would correctly adjust the oil pump arm and get the correct clips in place and watch it.

as far as admonishing your buddy.

dont.

when the remote tank level gets low enough to open the tank switch,SWB, the center bar(yellow lamp) is lit and automatic oil transfer is inhibited.
you will have 15-20 minutes before the engine tank is low enough to trigger SW3 and set the audible,visual red or far left bar and RPM reduction.

[SBSYNCRO]

I think I just figured it out... (Maybe?). Staring at the diagram in the parts schematic (above) I realized that the upper link (part #20) shows to be installed in the INSIDE hole of the lever off the second throttle plate. On my motor it is installed on the OUTSIDE hole of the lever that comes off the throttle plate! This would have to have a big effect, since the leverage would be completely different.

I have ordered the correct (white) retaining clip for the lower part of the control rod and the nut to keep it on, as well as the o-Rings for the oil pump shaft just for good measure.

Am I reading the diagram correctly - should the control rod be mounted to the INSIDE hole of that lever??? Yet another reason I continue to lose faith in my local marine repair shop.... (they installed it this way with these retaining clips and no nut)

Thanks!

[marktgb1]

excessive oil consumption

Hi,

Did you ever get you motor to run where it used a normal amount of oil? Mine is using around 25 to 1 and it is making me crazy. the dealer has not been much help.

[SBSYNCRO]

Nope, I've been chasing down many problems on this motor, and I've finally resolved all but this one. I have triple-checked the oil rod adjustment and I'm convinced that it is correct. Also the rod is supposed to be installed in the outside hole, so that's not the problem.

I just purchased a set of graduated cylinders to measure the oil consumption, which I'll do the next time I have some time (and an extra set of hands to help). If the oil pump is taking up out the right amount of oil, then the only remaining problem it could be a bent oil control rod. If it is taking up too much oil, then I'll run an output test and see if that is correct - if its CORRECT, then that would indicate bad seals leaking into the engine case. If the output is too much, that would indicate a faulty oil pump.

Good luck with yours - I'll bet you are having problems with idling too high, stumbling at mid-range and lack of performance at WOT. All those are probably caused by a fouled O2 sensor, which is caused by the over-oiling.

Have you pulled apart your O2 sensor to inspect it and clean it?

[jb123]

did you ever replace the orings? i think i mentioned them on the other site to you....

[SBSYNCRO]

did you ever replace the orings? i think i mentioned them on the other site to you....

Not yet. It looks like something best done when the boat is not sitting in the slip, and I've been waiting to pull the boat when I replace the prop here pretty soon.

One other factor thats probably contributing to extreme oil consumption is that I've determined that the boat is severely under-propped AND slipping badly (like 30% to 40% slippage!). This means most of the time Im running her between 4700 and 5100 rpms for extended periods of time. I'm sure this burns up a lot more oil than it would at 4000 to 4500 where it should be at cruise...

Is swapping the o rings easy to do? Are they the two parts I have highlighted earlier in this thread?