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First time impeller change questions Yamaha 40 hp

C

cooperfly

Member
I have a Yamaha 40 hp 40TLR 6H4K L - looking to change impeller for the first time. I have the impeller purchased looking for any instructions or advice on procedure. I have searched and watched a view videos and talked to Marina. They suggested putting motor in forward gear before I drop the lower unit

thanks for any info or links
 
If the gear box is in forward gear before dropping the lower unit, it would be near impossible for you to hand turn the crankshaft clockwise as you push down the impeller housing over the impeller. Gear box should be in neutral.

What year is your engine? If this is your first impeller exchange I highly advise getting yourself a service manual specific to your engine. Even for the most experienced marine mechanic, getting the collar and wave washer on/off can be arduous, as well as extracting a seized woodruff key.
 
ClassicAQ----With the lower unit off the motor it will be easy to turn the driveshaft by hand.----Makes no difference whether in gear or neutral !!
 
I mention turning the crankshaft solely because moving from gear to gear should be done when shaft is turning. Do you have the prop on when lower unit is dropped? If so, turn gear shifter all way clockwise. Now try to spin the prop clockwise with your hand. It should not spin. Then turn shifter all the way counterclockwise and spin prop counterclockwise. It should not spin. Put shifter in neutral gear. Spin prop by hand. It should freely spin in both directions. If prop doesn't do any of the above, you've got a gear box issue, either clutch or dogs, or something else.
 
oh well ----Post #2 and 4 seem totally different.----No need to confuse the owner of this motor ! -------When the lower unit is off and impeller is off it is easy to turn the lower unit.------In forward / reverse / neutral makes no difference !!
 
My plan was to put motor in forward gear, remove the 4 bolts and looks like I need to remove the anode also and there looks to be a bolt there also. Drop lower unit and then remove the impeller housing. Pull old impeller and put new one on. Replace the housing and reverse order all the bolts.

I have thought about a manual also - I believe the motor is a 2008

thanks for replies
 
Question to Racerone and/or Classicaq (obviously guys with great expertise) about the above procedure. I am just a weekend boater learning how to service my outboard, but have informally heard that it is convenient to put the outboard into gear before dropping the lower leg.


The reason stated was that, when you re-install the lower leg and push the drive shaft back up, it's splines have to mesh with the female splines in the top unit. If they are slightly off, the shaft won't go up, so if the unit was left in gear, it is convenient to just jiggle the prop while pushing up and the splines would mesh.


Is there any merit in that approach, or alternatively, any disadvantage?
 
Well, just find some u-tube videos.----Some good and some not so good videos on the topic.----Pick the one you like and try it.
 
cooperfly said:
My plan was to put motor in forward gear, remove the 4 bolts and looks like I need to remove the anode also and there looks to be a bolt there also. Drop lower unit and then remove the impeller housing. Pull old impeller and put new one on. Replace the housing and reverse order all the bolts.

I have thought about a manual also - I believe the motor is a 2008

thanks for replies
Click to expand...

Here is a link that directs you to the service manual for your engine, 2008 40TLR:
https://www.vansoutboardparts.com/s...aha-shop-manuals/227-2008-yamaha-40c-50c/file

The manual will state to remove prop before dropping lower unit. I don't, but that's just me. So long as you're careful I'd leave the prop on. That way you can hand turn the prop, testing that it won't spin in either forward or reverse gear. It also helps to have prop on when reinstalling lower unit just in case you need to turn drive shaft to align with crankshaft.
 
rmmu said:
Question to Racerone and/or Classicaq (obviously guys with great expertise) about the above procedure. I am just a weekend boater learning how to service my outboard, but have informally heard that it is convenient to put the outboard into gear before dropping the lower leg.


The reason stated was that, when you re-install the lower leg and push the drive shaft back up, it's splines have to mesh with the female splines in the top unit. If they are slightly off, the shaft won't go up, so if the unit was left in gear, it is convenient to just jiggle the prop while pushing up and the splines would mesh.


Is there any merit in that approach, or alternatively, any disadvantage?
Click to expand...

Definitely has merit. But just the same, if the LU is in neutral gear when reinstalling and you encounter the same problem you'd only need to very slightly angle the LU to find the groove. Once you've done this, push LU up while moving back to center line. 6--Half dozen....both methods give you the same result. Some have better success dropping in gear, others in neutral.
 
ClassicAQ said:
Definitely has merit. But just the same, if the LU is in neutral gear when reinstalling and you encounter the same problem you'd only need to very slightly angle the LU to find the groove. Once you've done this, push LU up while moving back to center line. 6--Half dozen....both methods give you the same result. Some have better success dropping in gear, others in neutral.
Click to expand...

Thank you, ClassicAQ, for your detailed answer.
 
I bought a manual, it does mention to slightly spin prop if needed to align the spline. It does suggest using Loctite 572 or 567 - or permatex 14A on the bolts for the housing and lower unit.

I am just changing impeller unless I find other issues.

any opinions I will take, about to take the plunge
 
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