Johnson 90hp skip,miss genius needed

[trendsetter240]

Re: Johnson 90hp skip,miss genius needed

Could some wear on the wrist pins only be responsible??

It could be responsible for a knock or ping but not the miss...

I'd be leaning more towards the missing a gear tooth idea at the moment. That sounds plausible for both symptoms.

 

[noelm]

Re: Johnson 90hp skip,miss genius needed

kind of doubt that a missing gear will be intermittant! it is OK or it's not.

 

[CharlieB]

Re: Johnson 90hp skip,miss genius needed

TLL you must be psychic I talked to a guy that does the machine work on powerheads today he told me the same thing. And no i didn't check the lower unit the thought never crossed my mind, but I can see how the sound could transmit right up the drive shaft. My next step tomarrow will be to check the lower unit. I'll get back to you guys on what I find.

If the condition does not begin to present until 2000 or above it is NOT a gear tooth per se, but it IS a worn shift slide and engagement dogs on Forward gear, camming and jumping out of gear part of a turn and slamming back in gear again.

Adjust the shift cable trunnion to give a bit more 'push' into geaar, two turns should make a difference.

If that cures it then start planning on replacing Forward gear and the shift slider.

 

[SparkieBoat]

Re: Johnson 90hp skip,miss genius needed

Me thinks Charlie has hit the jackpot here.

 

[trendsetter240]

Re: Johnson 90hp skip,miss genius needed

I put a large screw driver against the crank cover and to my ear (it does work ). listened for the noise moved it around and it sounded like it was coming from the top of the crank/flywheel.

How did you perform this test? Did you hear the noise while turning the flywheel by hand? Was the engine in gear?

If the engine was in neutral and this test was performed with the engine off or at idle I don't see how a worn shift slide and engagement dogs on Forward gear would cause the knock.

Maybe you are dealing with multiple issues here....

 

[pick401]

Re: Johnson 90hp skip,miss genius needed

How did you perform this test? Did you hear the noise while turning the flywheel by hand? Was the engine in gear?

If the engine was in neutral and this test was performed with the engine off or at idle I don't see how a worn shift slide and engagement dogs on Forward gear would cause the knock.

Maybe you are dealing with multiple issues here....

I just ran it in neutral. Withs the mouse ears on. Your point is well taken a would a worn shift slide do this with no load on prop?

 

[pick401]

Re: Johnson 90hp skip,miss genius needed

TLL you must be psychic I talked to a guy that does the machine work on powerheads today he told me the same thing. And no i didn't check the lower unit the thought never crossed my mind, but I can see how the sound could transmit right up the drive shaft. My next step tomarrow will be to check the lower unit. I'll get back to you guys on what I find.

Drained the lower unit oil today. A smidge darked tha honey no sign of water. No significant metal shavings. I would assume if a gear tooth was missing and rattling around I'd have a significant amount of shavings.Going to run it and listen for sound coming from lower unit when I get the timing wheel in. But it's not looking to promising. Thanks for all the great ideas. Sooner or later I'm going to win and figure this thing out. When I do you guys will certainly hear about it.

 

[CharlieB]

Re: Johnson 90hp skip,miss genius needed

Try biasing the shift cable to give more 'push' into gear.

I've run into this a few times, the customer had replaced his whole ignition, with NO change. 'Cause it was NOT a motor problem.

 

[SparkieBoat]

Re: Johnson 90hp skip,miss genius needed

significant shavings not necessary, is probably not a broken gear tooth but rather wear on the clutch dog and or forward gear, will cause it to jump occasionally sounding like an engine skip. If you can get your hands on a used gearcase to borrow and do a test run...my money is on the gearcase clutch dog on this one. and it would probably not do it on the muffs but only under a load. you can take your current gear case apart and look at the clutch dog if you want but it is usually best to replace the seals if you do this. here is a pic of my clutch dog that had to be replaced.

 

[SparkieBoat]

Re: Johnson 90hp skip,miss genius needed

well that is a pic of my forward gear, you can see the slight wear on the edges of where the clutch dog mates