90 merc lower unit

[Plains Puddlerunner]

Just bought a old (1981) 90 H.P Merc. The lower unit appears to be junk. It has forward,forward, and forward. I checked the shift rod and it is turning so I can only assume that the lower unit has serious problems. My question is this, I have the service manual and a good selection of tools along with a little mechanical ability, is a lower unit rebuild beyond the novice mechanics ability on this unit. Any advice would be welcome. Thankfully I have a Evinrude to install on my pontoon in the interim but I still want to fix this merc.

 

[mnmfors]

Re: 90 merc lower unit

hi, I also have a 90 hp merc. I am no expert but here is what I could suggest.. I am guessing that the shifting rod is not slipped over the gear spline in the lower unit (these are male and female and fit together) If you could pull the lower unit down just a little, you could visually inspect to see if it mated correctly. Also, I have had good luck in removeing the lower unit with the motor shifted into forward, and not shifting back until lower unit is back on. Just a thought. Good luck.

 

[alcan]

Re: 90 merc lower unit

Hi Puddlerunner<br />I agree with mnmfors. You just bought a new used motor from god knows who. You need to remove the lower unit anyway. I'm thinking you will find the shift shaft is not indexed properly. Service the entire unit before using. Your manual will tell you how. Hey, if you do end up having to over haul that L\U we're here to answer questions. Let us know what you find out.