Flywheel thread sizes for puller

[engrkenr]

My 1968 Model 60 6.0 Hp flywheel needs pulling. I cannot determine the 1/4 inch thread number for the 3 puller attachment holes. They don't seem to be 1/4 20 or 1/4 28. Are they something else? I don't want to force bolts in there and risk cross threading. Someone must know?

 

[racerone]

How about 5/16-NF

 

[merc850]

I'll bet they're 1/4-32.

 

[racerone]

1/4- 32 ----Really ??

 

[engrkenr]

The tapped holes are definitely not 5/16" and the thread looks too coarse to be 1/4 32. Could they be #12 - 24 which is slightly smaller than 1/4" but that thread gage looks about right. In my Merc repair manual, a reference is made to flywheel puller tool C-91-24695A2 but, there is no mention of thread size for the tapped holes.

 

[racerone]

I have pulled a flywheel off a 68 model 6 hp.----Had no trouble / did not need special tools or bolts.----The question is on your motor has any modification been done in the past ??----Maybe I check later today what they are on an unmolested flywheel !!

 

[engrkenr]

Although there has been work done on the motor years ago, I doubt that any modification was done to the flywheel because there is red overspray paint visible in the tapped holes which is an indicator of typical manufacturing processing characteristics through a spray booth.

 

[Chinewalker]

I've always thought they were 1/4-28 on those smaller Mercs. Mercury used the 1/4-28 threads everywhere....

 

[engrkenr]

Its with great humility that I confess to have way out in left field on this....the tapped holes in my flywheel are 5/16 and most likely 5/16 24. My only excuse is that I borrowed the puller and was told most of the array of accompanying bolts were 1/4 20's whereas most are actually 5/16 18's and some may even be metric. That will teach me that I should have invested in a set of thread gauges! My apologies.​

 

[racerone]

There you go !-----5/16-NF as per post # 2

 

[w2much]

I am working on a few motors at this time. . A Mariner a Merc a Suzuki and an Johnson,waiting for parts. I had the same question regarding the bolt holes for removing the flywheel from the Mariner. None of the bolts worked as I thought they should. I finally tried a bolt from the lower unit of the Suzuki and it worked . I came up with 8mm and a 20 thread. I wrenched it in , it was the correct size. This was on the 1992 Mariner 9.9. It appears original as the motor is in pristine shape and the holes still have black paint in them. I tried 1/4 and 5/16 with different thread counts. Perhaps Mercury part # ........... is just a metric bolt.