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Help with early 80's Merc 7.5hp. Bad Reeds?

J

jdparsons1

New member
I have an early 80's Mercury 7.5hp (Serial #:6110787) that came on a boat i just purchased a month ago. The previous owner started it in a bucket for me and showed the forward/reverse worked but really never got the rpm's up on it. I just started it yesterday in a garbage can and it started on the 2nd pull. One thing i noticed though is it sounded like the flywheel was rattling and it was causing the whole engine to jump i wanted to see if the noise got better or worse when rpm's were up so i revved it about half way in neutral and there was an abrupt stop followed by a backfire. The motor wont start at all now. Spark is good and i've got around 130psi in each cylinder for compression. One thing i noticed was the whole time it was running the carb was leaking out of the opening. My first thought was i had two issues, something with the recoil starter rattling and maybe float level in the carb. But now that i'm looking at the exploded diagrams im wondering if this could be a reed issue. I believe my engine has the circular reed valve mounted at the top of the crankshaft just under the flywheel. Anyone here familiar with those and how much effort it is to get to them to inspect? Anything specific to look for or other thoughts?
 
Well thats good to hear! :) I will pull the flywheel later today. One more quick question, the floats on these things look to be foam, do they "go bad"? float level looked decent but for some reason that carb was dripping all over the place. Maybe the needle/seat is worn.

fastjeff said:
It's not reed valves--they are stone reliable on Mercs. Look for a sheared flywheel key.

Jeff
Click to expand...
 
So i pulled the pull starter off and one thing i noticed is that all 3 of the starter pawls are kind of just flopping all over the place like the springs are worn out. i can reach down with my finger and there is almost no resistance to move them to extended position. im thinking... if these are flopping around when the motor is running and occasionally catching on the fly wheel that could definitely cause it to run rough. Sound right?

fastjeff said:
It's not reed valves--they are stone reliable on Mercs. Look for a sheared flywheel key.

Jeff
Click to expand...
 
The reeds are in the center main bearing. Yes the pawls have a wavy washer that holds them retracted when the rope gets pulled in. The plate has three tabs that wear out from the pawls getting slammed around you may need to replace the plate also? Put some fuel mix directly in the spark plug holes and see if you get fire?
 
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