FastTracker
Recruit
- Joined
- Sep 19, 2026
- Messages
- 5
Hello - this is my first time here and definitely my first time taking a motor apart. I’ve got a 2001 Mercury 40 2-stroke that came on a 1-owner grizzly Tracker I bought a couple months back.
Ran it a few times and seemed to run fine. We took it out on the lake for a long day, pretty loaded down and ran her pretty hard and it was hot outside. Right at the end of the day it started knocking. I took it back out a week later and ran it really low and slow and it was still knocking like crazy.
Basically couldn’t find anyone to take a look at it - either they wouldn’t, or said it would probably cost more than it’s worth to tear it down, so I found a YouTube video and took it apart. Don’t know much about what I’m looking at, but a few things do jump out (to my untrained eyes).
Seems very, very dirty to me - it’s like this weird watery sludge on the reed valve (name?) and all over the inside of the block. Also looks like there wasn’t any type of gasket between halves of the crankcase - is that normal?
Also looks like blowby on the pistons. Is that probably worn rings or something worse? Should I think about boring it out and going back with oversize pistons or just replace rings?
Doesn’t really seem to be any scoring on pistons or cylinders that I can see. Really doesn’t seem to be any play in anything either.
I bought an overhaul gasket kit and the metal piston rod bearings to replace the plastic ones.
Would really appreciate any insights on what might have been causing the knocking and what I should check while I’m in here.
Thanks in advance - I can follow along with paint by numbers YouTube’s, but that’s about where it ends so anything big or small is much appreciated. Anything cheap and easily replaced while I’ve got it all ripped apart? Anything to NOT touch/replace?
Thanks!!!
Ran it a few times and seemed to run fine. We took it out on the lake for a long day, pretty loaded down and ran her pretty hard and it was hot outside. Right at the end of the day it started knocking. I took it back out a week later and ran it really low and slow and it was still knocking like crazy.
Basically couldn’t find anyone to take a look at it - either they wouldn’t, or said it would probably cost more than it’s worth to tear it down, so I found a YouTube video and took it apart. Don’t know much about what I’m looking at, but a few things do jump out (to my untrained eyes).
Seems very, very dirty to me - it’s like this weird watery sludge on the reed valve (name?) and all over the inside of the block. Also looks like there wasn’t any type of gasket between halves of the crankcase - is that normal?
Also looks like blowby on the pistons. Is that probably worn rings or something worse? Should I think about boring it out and going back with oversize pistons or just replace rings?
Doesn’t really seem to be any scoring on pistons or cylinders that I can see. Really doesn’t seem to be any play in anything either.
I bought an overhaul gasket kit and the metal piston rod bearings to replace the plastic ones.
Would really appreciate any insights on what might have been causing the knocking and what I should check while I’m in here.
Thanks in advance - I can follow along with paint by numbers YouTube’s, but that’s about where it ends so anything big or small is much appreciated. Anything cheap and easily replaced while I’ve got it all ripped apart? Anything to NOT touch/replace?
Thanks!!!
