Merc inboard 454 GenVI flywheel issue?

[Redhook98]

Good morning all! I had my port motor in my 38-ft carver blow back in July. Ordered a rebuilt GenIV, but they ended up sending me a Service Replacement (Gen VI with fuel pump boss). The flywheel and harmonic balancer are not the same. have a brand new balancer on the way, but been struggling with the flywheel. Finally bought one off of Ebay for a GenV/VI and it arrived yesterday. Just occurred to me that it is most likely for a sterndrive though. Part number is 10101171. I have heard of people removing the 168-tooth ring, heating it and installing on the other side of the flywheel. How difficult is this? Is a 10101171 for a sterndrive? Or inboard? Hard to find info. Thanks!

 

[achris]

Got a serial number for that engine? Or even a year?

 

[aimlow]

Are those thing internally or externally balanced??

 

[Redhook98]

Got a serial number for that engine? Or even a year?

Sadly, no. Could not find a serial number anywhere on it. It is a "Gen S" is all I know. 6-bolt front timing cover, 1 piece rear seal. Can't find a serial number anywhere on it. All I have to go on is it for sure is it is based off a Gen VI, thus the need for a GenV/VI flywheel.

The company I bought from out of CA was supposed to send me a Gen IV. Got this one, with no info instead.

 

[kenny nunez]

Switching the ring gear is no problem. Heat or a brass punch and a good hammer will do the job.. It will be a good idea to get a new ring gear to install on the other side of the flywheel. NAPA usually has them. Since you have a heat source it will be easy for you to mount the replacement gear.

 

[Redhook98]

So it is just simply moving the ring gear from front to the back of the flywheel?

 

[kenny nunez]

That is correct but be sure to get a new gear. The last thing you want is a slipping or split ring gear they do not cost very much.

 

[alldodge]

Sadly, no. Could not find a serial number anywhere on it.

Look on the rear deck of the block below the distributor for a casting number

 

[Redhook98]

The casting number is 12550313

 

[alldodge]

The casting number is 12550313

12550313...454.......91-up...4-bolt, Gen.V crate motor, Gen. VI 4.25" bare block, fuel pump boss

 

[Scott Danforth]

use your old flywheel

gen V and VI engines use the same flywheel balance (external) and are both 1-piece RMS cranks.

sterndrive flywheel is just a GM truck flywheel

Inboard flywheel is a Mercruiser (or other marine engine supplier) special. It does not come from GM.

 

[Redhook98]

My old flywheel is from a Gen IV (4). Not compatible with a Gen V/VI. (5/6). Different weight differential in the flywheel and harmonic balancer (from what I was told)

 

[Scott Danforth]

balance is different, however a good automotive machine shop that does balancing could re-balance your Mark 4 to a Gen V/VI

 

[Redhook98]

How about the harmonic balancers? The one I bought new was for a Gen V. I thought they were the same as well. I believe it is too deep by 1/8th inch.

 

[Redhook98]

Merc Harmonic Balancer difference Gen V and Gen VI?

Having solved my flywheel issues by buying a new Gen V/VI unit, I now move on to the Harmonic Balancer. I thought Gen V and Gen VI were the same there as well. I found a brand new Gen V balancer, but it seems to be 1/8 inch to long (crand is 1/8 inch recessed to far into balancer bore. Can I just have 1/8th inch machined off the back of the balancer? Or is the difference in depth made up somewhere else?