85 HP Lower Unit Trouble

[reppondj]

I have a 1986 85 hp 856X6L. Been running just fine with no troubles. Changed the oil in the lower unit, old oil looked good, no water, no shavings. Went to the river after changing and all was well. The next weekend trouble started immediately after putting in the water. At idle and mid throttle it ran fine, at WOT the motor started jumping as if I were hitting stumps, the water was open with no obstructions. This happened about 6 times fairly quickly before I shut it down. Idled back to the dock with no probs. When I got ready to load, it would not even move at idle without a loud grinding noise. <br /><br />Got back, drained the oil, it was clear, had a few silver shavings in it and a whole lot of brass shavings. Removed lower unit to take apart and see what the prob is. I cannot get the gear housing cover off. The manual (SELOC) says to pry it off with screwdrivers, well I believe it would break before coming off. Any suggestions, will heat hurt it, obviously its broke but dont wont to break it more,.........

 

[javsam]

Re: 85 HP Lower Unit Trouble

 

[RRitt]

Re: 85 HP Lower Unit Trouble

you can buy them cheaper than you can rebuild them.

 

[imported_LakeRunner]

Re: 85 HP Lower Unit Trouble

Make sure you have removed ALL the bolts, Force likes to hide them under the Zinc sometimes!

 

[getusum67]

Re: 85 HP Lower Unit Trouble

i,m having the same problem if i take off full speed the same thing like i,m hitting stumps, i,ve been told that its my dog gear going bad ,if i take my time getting up on plain it dont make that hellish banging like hitting stumps. let me know what u find out about your moter. my email duckiekiller@aol.com

 

[RRitt]

Re: 85 HP Lower Unit Trouble

back in 2001 I ran aground and took the boat to a mercury dealer for repair. It was the one, only, and last time that a mercury mechanic has ever touched my engines. When I got it back the engine had a hard time staying cool at idle, the engine died everytime I put it in gear, the engine had slight knocking noise at WOT, and the gearcase went clunk, clunk, clunk. At first I thought that I had messed up the lower unit and maybe even the motor. I even went so far as to buy a replacement gearcase.<br /><br />When the day came to put on my gearcase I discovered the real source of my problems. Shoddy but high priced workmanship from the dealer.<br /><br />The impeller housings were not replaced. They were deeply pitted from the sand and shells.<br /><br />The shift linkage was six full turns out of adjustment.<br /><br />The idle speed had been set in neutral instead of in gear.<br /><br />The mixture was set too lean.<br /><br />It's a good thing that I fixed it. I believe the engine would have self-destructed if I had run it in that condition. I'm still undecided whether this was simple ineptitude or an attempted sabatauge so that I would buy some new mercs.<br /><br />Either way, check the settings on your shift linkage. Disconnect the pin at bottom. push it down while rotating prop by hand until is just engages. make a mark on linkage rod. then lift rod until it just engages and make another mark. With throtttle in neutral your pin should align between these two marks. On my engine, the highly trained mercury machanic was off by about 1/2".