Logo

Question for Graham on 1993 9.9 hp merc

I am doing a powerhead swap on a 93 Merc 9.9 I got the flywheel off the old and the new won't budge. I am switching flywheels due to the new powerhead did not have electric start and my old one did. I have had a puller on it, tightened as tight as possible, whacked the top with a hammer a few time(actually a bunch of times) and heated the shaft lightly, and still will not come off. What next? What size are the 2 bolt holes on the top and does the flywheel have to be oriented in a specific way to use the bolt holes or in anyway to come off? Thanks in advance.
 
Re: Question for Graham on 93 9.9 merc

Can't tell you the bolt sizes - I kinda pick around the bolts in my puller case until I find something that fits :)

Doesn't need to be oriented any special way.

Heat the snot out of it again - get her good and hot then spray it with some cold water (one of those little trigger water bottles would be enough water).

Sometimes quickly cooling the heated/expanded metal will make it "break the seal".

That's about the only other trick I have.

I remember back the very first time I was pulling a flywheel on a 7.5 horse (was probably about 12 years old) and I couldn't get it to budge - but was also worried about putting too much stress on the puller or hitting it too hard with the hammer and damaging something.

Anyhow, I fiddled with it for probably well over an hour - my Dad (who had been a small engine mechanic for over 20 years at that point) suggested the heat trick - did it, put the puller on, reefed good and tight, still wouldn't move.

I was about to give up when my Dad walked over with a 3lb ballpeen hammer and cracked her a good one (I mean one good whale) - popped right off :)

When I asked him about whacking it that hard and maybe causing damage, he said something like "replacing a crank seal is easy once the flywheel is of and you have the case cracked" (lol)
 
Re: Question for Graham on 93 9.9 merc

Pretty sure they are M8 or M10 threads, I know they are Metric for sure. They can be a bear to get off. The 25's are like that as well and the large crankcase bolts fit the holes in the flywheel but cannot recall if they are 8 or 10.
 
Back
Top