2006 honda 150

I have a problem that has been going on for a couple of years now on and off. The noise happens on a cold engine when I give it some rpm's backing off of trailer an when I go to neutral it sound like a loud grinding and scraping noise. When I put it in gear it goes away. After it warms up a bit it stops. I have had it in shop 3 different times.Thought it might be shaft bushing but that is ok. after pulling the lower unit 3 times i have determined that the noise is coming from the top of the lower unit shaft right below the spline that connects to fly wheel.Removed starter to look at fly wheel. That looks good no corrosion.I did start engine without lower unit to make sure noise was coming from lower unit. last time I put omc tacky grease at top of shaft seems to help.

without lower unit does the noise was same ? did you remove engine oil and see for any metal debris.?

wajira

No noise with lower unit off.Checked engine oil and lower unit oil no signs of metal.Right below spline on shaft was very shiny and had three race marks on shaft

How old this engine ?below spline on the shaft their is two water seals, some times those seals and below of seals get corrosion. can you see the water seals mark on the shaft ?and where is the exactly that shiny mark ?

733 hrs.The shiny mark is right below spline wit 3 race marks on the shiny part.Can you tell me what Is involved in replacing those seals.

some times when this seals are bad water enter to splines and you will have stuck vertical shaft in flywheel boss.(where the splines sit ) and some case engine oil leaking down through vertical shaft, changing those seals is big job you have to lift up full engine,then only can see it. it sounds like at neutral vertical shaft vibrate and rub something. if it is some corrosion in the under case the mark should come little down. not close to spline. you can clearly see that water seals lips mark just below spline.

wajira

Thanks for your help. I will be speaking with Honda tech this evening as to witch direction to head. I think the seals may be ok I could see the fly wheel area pretty good with the starter off and a good light . I'm not sure what the neutral vertical shaft is but I ill ask him about it.Wish I would get this problem solved has been a great engine !