help me with my mercury 40 4hp

[adk_vfr]

Hey guys I picked up a 1978 mercury 40 4hp which I wanna use for trolling. He told me that it ran but needed impeller. I pulled the foot off and the impeller had basically turned into a pile of rubber chunks. I was gonna order the kit but as I was spinning the driveshaft with the foot off it didn't seem smooth in the foot it has a gear on fear feel and sound. I told my buddy about it and he seemed to think it was no big deal and was all good. Do you guys know anything about these motors if so your info would be appreciated. Thankyou

 

[quicktach]

Re: help me with my mercury 40 4hp

This is a FOUR hp? What is the serial # ? Is there any oil in the lower unit?

 

[adk_vfr]

Re: help me with my mercury 40 4hp

Yup like the title says mercury 40 4hp and it is serial# 9172840 there was oil in there but not much and a little water. The foot sat half bolted on for a while as he took it off to fix the impeller a year or more ago and never finished so not sure if water got in while sitting. The top vent bolt is just a plain bolt with no seal as well so I'm sure water gets in there as well. The noise I'm hearing is not while running this is while holding the foot in my hand with all water pump parts out and spinning driveshaft with hand. I've never taken a foot apart so not sure what in there would make this sound or if it should.

 

[jbjennings]

Re: help me with my mercury 40 4hp

I would fill the lower unit with marine gear oil, put a new impeller AND new water tube grommets and put it on the motor and run it. The lower unit is very simple. THere is a bearing for the driveshaft right above the pinion gear, and two roller bearings (one on each end) on the prop shaft. The pinion and forward gear are pretty plain, coarse gears and do make some noise. The water in the lower unit does make for some suspect roller bearings, though. How it FEELS would be as important as how it sounds. If it feels all gritty as you turn it, I'd take the lower unit apart and check for pitted bearing races or pitted ball bearings and pitted gears.