How Long do Lower Leg's O'rings Lasts ?

[Sea Rider]

On last 100 hour use the gear oil of my 18 HP was found with some milky portions not fully mixed though, apparently the seals are in the process of being fully shot and in need to order a lower leg kit shortly. As not sure of this situation will give it a go 50 more hours, drain and inspect all the oil to know.

Was wondering what could cause a premature o'ring failure if gear oil is changed each 100 worked hours, prop has never hit a under water object, lower leg works in clean non sandy waters condition.

The OB has already metered 900 hours of constant well cared use. In my previous 18 HP horses with 1 K metered worked hours have not seen this situation before. Seems it's proper time to sell it as summer is close and install a new one LOL!!

Happy Boating

 

[pvanv]

It all depends. Age as much as hours determines how well the rubber lasts. At nearly 1000 hours, it's time.

 

[Sea Rider]

It all depends. Age as much as hours determines how well the rubber lasts. At nearly 1000 hours, it's time.

Thanks Paul,

As usual a informative answer, will order soon a lower leg kit, anyway will check what has happened in next 50 worked hours just for the record...

Happy Boating

 

[Sea Rider]

Paul, if ordering a Lower Leg Kit, will I need to order other related parts, excluding water pump parts ?

Happy Boating

 

[pvanv]

Nope, the kit is complete. I would be happy to ship one to you.

 

[Sea Rider]

Is this a straightforward thing to change, just pull out all older parts, assemble new ones in, make a pressure lower leg test and that's it ? Haven't changed one in my entire boating life and plan keeping this nice 18 for many years to come....LOL!!

Thanks, will let you know.

Happy Boating

 

[pvanv]

Yep. A few gaskets and o-rings. Be careful doing the inner o-ring for the cam rod. That will test your dexterity. I use a dental pick to get the old one out, and a smooth punch to install the new one.

 

[robert graham]

Did you check for some fishing line around prop shaft causing leakage and/or prop shaft seal damage?....

 

[robert graham]

Did you check for some fishing line around prop shaft causing leakage and/or prop shaft seal damage?....

 

[Sea Rider]

Did you check for some fishing line around prop shaft causing leakage and/or prop shaft seal damage?....

No fishing lines whatsoever. Apparently had a slight water intrusion on lower leg due to normal wear, a small oil portion came out slight whitish. On next 50 hour run will check if the situation has gone extremely bad and install a new lower leg kit following Paul's spot on removal and installation procedure.

Happy Boating

 

[Sea Rider]

Went for a new gear oil change not precisely at 50 metered hours but way less as will hate to find the internal lower leg gearcase flooded with sea water. Bingo, oil came out with a clean mustard darkish yellow color, not the initial blonde yellow color as when gear oil is brand new with no metal fillings whatsoever...

A long short story..

On last restoration went for local head and exhaust gaskets, although well cut proved to have down issues, both were found extremely compressed due to heat at only 5 run hours. A retorque to specs was mandatory, had lost completely the factory torque both gaskets were previously torqued to. Removed both plugs, were found medium rusted, with dark brown color, synonym of water intrusion in combustion chamber through any of both leaking gaskets.



When powerhead was removed from base as it's impossible to retorque lower head bolts adequately, a whitish creamy sludge was found right under large crankshaft's oil seal...(yellow circled area)



And around pan's drive shaft area...(whitish greased area)



Question :

-Would it be possible for gear oil to have traveled through lower leg and be collected side of drive shaft ?
-Would it be possible for 2 strokes oil and salt water to have emulsified on combustion or exhaust chamber and made its way through lower crankshaft's large oil seal ? Thoughts, experiences...

Pan gasket is 100% operative, was well torqued to specs so salt water didn't come that way...

From experience, will never buy local gaskets, material sucks and can easily screw a nice OB....

Happy Boating

 

[pvanv]

Likely 2-stroke oil and some grease emulsified. Doubtful for LU lube to travel that far up the drive shaft.

 

[Sea Rider]

Likely 2-stroke oil and some grease emulsified. Doubtful for LU lube to travel that far up the drive shaft.

Yep, seems a salt water and 2 stroke oil emulsification ? Paul is it normal for drive shaft exiting oil seal at upper pan to move laterally when wiggled. Should move a slight bit or not move a bit ?

A strange thing happened, removed both rusted plugs and installed 2 used ones in apparent good cond. When OB was started on muffs after exhaust and cylinder head gaskets were torqued back to factory specs the OB idled fine at neutral and revved up when geared and throttled forward.

When combo was lauched to sea, the OB lost it's power, did not missed, just revved up very slow no to full wot rpm range though when combo was geared forward. If spark plugs were found oxidized, it it possible for piston o'rings to have been compromised too ?

Will make a new cylinder compression test, add 2 new brand NGK spark plugs and see what happens...fingers crossed!!

Happy Boating

 

[pvanv]

Luis,

Any side play of the crank shaft is due to bearing clearances. Could be a couple of thousandths. As for the drive shaft itself, there is also the spline clearance, so a couple more thousandths. Altogether, should not have much side play unless the bearings are quite worn.

Sometimes wrong or old plugs will fire, but not as well, and the motor can be sluggish. I would install proper new NGK plugs, run a compression test, and go from there. Since rings move around, unless they are carboned in place, they should be OK at low to medium hours; However, if a lot of water was run through, they could get rusty, sticky, and worn. Running for a couple hours under load without water intrusion may help correct that.

 

[Sea Rider]

Thanks Paul,

Drive shaft bearing, as there was no salt water emulsified found with gear oil, assume that lower bearing (650-302-110) located under water pump is still in good condition, if severely worn would it produce some sort of noise ? Has never ocurred to me to wiggle hard a new drive shaft and see how much side play it has LOL!!

Applied an overdose of carbon remover through carb with engine ON for 5 minutes, should have taken care of anything building on piston rings already. Have bad luck installing used plugs, usually throw them into the blue after 100 worked hours. Tomarrow will perform a compression test and install 2 new spark plugs...

Happy Boating

 

[Sea Rider]

To clear whatever was built on piston rings, made a 5 minute run geared forward on muffs at constant 2 K while squirting small dosis of Engine Tune UP decarbonizer through carb. When product was totally burned, made a compression test, the engine now has 120 PSI on both cylinders, a 10 + PSI gain from last test. This product is amazing..



A new spark test indicated IC intensity being very strong. With 2 new NGK BR7HS-10 went for a wot run as if stealing the combo, now idles and runs smooth, achieved 5930 wot rpm lightly loaded. It was an american breakfast buffet difference LOL!!

Happy Boating

 

[Sea Rider]

Removed power head for third time for a head and exhaust covers final re torque. With just 5 run hours from last re torque the pan area located under lower crankshaft oil seal was found emulsified as in pic. That's way, way less than last time where the round pan portion was full.




Question : Is it possible for that big oil seal to fail over time specially if that nice horse has run for 900 metered worked hours as it's nearly impossible for gear oil to have traveled that far from where its located..

Happy Boating

 

[Faztbullet]

Smell it...............

 

[Sea Rider]

Smell it...............

Thanks, but late for that, power head is already assembled. It's consistent as mayonnaise. What's strange is that there is no water path located under lower crankcase seal where seal rests against pan to be a salt water emulsification issue .



All water paths starts at a much larger distance from drive shaft as in pic. Pan gasket is in one piece and in excellent sealing condition torqued to specs..

If it be 2 strokes oil/and fuel mix leaking through worn lower crank gasket at wot, would it be white and creamy ?

Happy Boating

 

[Faztbullet]

Most likely leakage thru seal...was this after the power tune treatment????