ferret

lower unit break in

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My insurance co paid for a new lower unit on my Yamaha F250, it is on way.  Kind of confused about the break in procedure as most posts refer to a new motor, mine is just the new lower.  I get that you should vary rpm every 5-10 min and should rarely go to wot if at all for the first 10 hours.  But many suggest that you should rarely go beyond 1/2 throttle during the first 10 hours.  Assuming I can get 6000, does that mean 3000?  If so, that's not on plane for my hull.

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Breaking in a motor is completely different than a LU.

I don't even think you need to break in a LU.

You may want to change the oil in half the interval the first time though.

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I agree,  dont think you need to break in a lower unit. It might be wise not to beat on it right off the bat, and as stated change the lower unit oil after the first couple trips. 

 

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thats good news, im probably use it for April then pull it til September, aint much doing inshore in NJ in the summer months, will change the fluid after April

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1 hour ago, ferret said:

My insurance co paid for a new lower unit on my Yamaha F250, it is on way.  Kind of confused about the break in procedure as most posts refer to a new motor, mine is just the new lower.  I get that you should vary rpm every 5-10 min and should rarely go to wot if at all for the first 10 hours.  But many suggest that you should rarely go beyond 1/2 throttle during the first 10 hours.  Assuming I can get 6000, does that mean 3000?  If so, that's not on plane for my hull.

 

34 mins ago, Billybob said:

Breaking in a motor is completely different than a LU.

I don't even think you need to break in a LU.

You may want to change the oil in half the interval the first time though.

BB is right.

 

Change the LU gear oil at t10 or 20 hours and have fun.

 

Love the smell of that stuff btw

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No break in  on lu just gears. Not like a new  motor where your trying to set the rings  . Juts grease shaft probly ,bolt and have fun. Imo i would beat the crap out of that lower unit  just to make sure my drive gear in the  powerhead wasn't stripe.and is holdin ip.,I'm sure you get some type of warranty for a few days. ... 

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Posted (edited) · Report post

Newer lower unit?   Are you getting a new propeller too?

 

Like most said, change that oil sooner.  Some gearcase are put together with assembly lube, some just the lubricant.  But most all use some sort of o-ring grease during assembly.   Not horrible to have that in too long, but not that great either......  Before your first change, I'd run it in reverse a good number times too.  That shift fork surface needs to make a wear pattern too. 

 

Drain the oil right after use if possible to have stuff suspended in oil.   When draining, drain it in a clean open face pan so you can see what comes out.

 

I boat in rocky areas alot.  I kind of feel the cheaper aluminum props are cheap insurance against major lower damage.  However, my props for my little outboard are only +/- $50.   I actually buy 2 at a time....   I think a good hit with a stainless is gonna damage the lower gears n bearing worse.

 

Alot of fishmen in my area use a kicker.  More for nasty spots than for trolling.  You'd be really surprised how well a small 6 or 8hp motor will push something v8 or large m otor like yours usually pushes.

Edited by salt deficient

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Posted (edited) · Report post

A friend got  a new lower unit for his Yamaha 225. He was instructed with a written note to keep it below 3000 rpm for the first 5 hours and not to go WOT until after 10. Also to shift at least ten times before 10 hours. 

Edited by Tomm24

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Once you got that in for awhile, recheck the shift linkage adjustment.  You want it to be floating in one spot and not have the shift fork riding against any resistance, 

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8 hours ago, Stonesipher said:

Just follow the original breaking in process from the mfg when new. They just weren’t referring to the power head.

Yeah, they most likely were

 

I got two new lower units compliments of Sandy when my rig went forward and over my neighbors lift.  Those I beams did a number on the L/Us, oddly not a scratch on the hull thank god

 

In any event, I ran them like I stole them.  Drained the oil at 10 hours, doubt I even had to do that, was  perfectly clean.

 

In todays world of CNC machined gears, its a non issue.  Tolerances are tight nowadays baby!

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