4.3 volvo penta flywheel problems

[Henry 68]

Hey all hoping someone on here can gelp me , i have a 4.3 votec volvo penta with sxm outdrive. I bought the boat with a blown motor and being a licensed truck and auto mechanic figured no big deal. Got myself a 4.3 vortec out of a gm truck amd swapped out the engine . I did have to use the crankshaft from the truck engine but everything seemed fine. Reinstall the engine into boat everything ran fine . Water tested and all was fine for the first 20 minutes or so when i developed what sounded like a rod knock. Turned out the flywheel had come loose . No big deal tightened everything back up , even applied red loctight to hopefully prevent this from happening again . But the exact same thing happened . I cannot see what is or went wrong . Any help would be greatly appreciated... sorry for the lengthy post but i figured i should give as much detail as possible.

 

[Scott Danforth]

What year VP motor? what year truck motor?

Did you mix parts from a balance shaft motor and a non balance shaft motor?

 

[Henry 68]

What year VP motor? what year truck motor?

Did you mix parts from a balance shaft motor and a non balance shaft motor?

The vp is out of a 99 four winns and the truck motor is out of a 99 gmc jimmy. Both engines are balance shaft , roller rocker engines..

 

[Scott06]

First thought would be a balance issue from mix and match parts as Scott outlines. Did you use the whole truck engine or pull the crank and swap that into the VP engine? Are the blocks the same casting number?

The loctite will take time to fully cure especially if outside in colder weather. Possible it wasn't set up yet, or incorrect bolts were used ?

 

[Lou C]

What about the difference between automatic transmission flywheels and manual transmission flywheels? Did you use the flywheel from the original marine engine or the truck? I think with the VP style coupler the same bolts that hold the coupler on hold the flywheel on, unlike some Mercs.

 

[Henry 68]

Ok so the guts (crank and pistons ) are from the truck engine and the cam is out of the marine engine. The flywheel, coupler and bolts are from the marine engine . The bolts are actually studs and nuts from the vp that hold the flywheel and coupler on the crank .

 

[Lou C]

I'm wondering if could it be that the studs were not tight in the threads in the flywheel even though the nuts were tight to the coupler. Might have to double nut the studs to get them tight enough. OMC used this exact same way of attaching the flywheel to the crankshaft and the coupler to the studs. The nuts are supposed to have lock washers and you are supposed to tighten them to 40-45 ft lbs.

 

[Scott Danforth]

Ok so the guts (crank and pistons ) are from the truck engine and the cam is out of the marine engine. The flywheel, coupler and bolts are from the marine engine . The bolts are actually studs and nuts from the vp that hold the flywheel and coupler on the crank .

you swapped rotating assemblies from one block to another?
pistons cant just be pulled from one bore and shoved in another unless they are virgin bore new motors

at a minimum, you need to bore and hone the block and get new pistons and rings.

 

[Henry 68]

you swapped rotating assemblies from one block to another?
pistons cant just be pulled from one bore and shoved in another unless they are virgin bore new motors

at a minimum, you need to bore and hone the block and get new pistons and rings.

Crank and pistons are from the truck engine only the camshaft was changed

 

[Henry 68]

you swapped rotating assemblies from one block to another?
pistons cant just be pulled from one bore and shoved in another unless they are virgin bore new motors

at a minimum, you need to bore and hone the block and get new

I'm wondering if could it be that the studs were not tight in the threads in the flywheel even though the nuts were tight to the coupler. Might have to double nut the studs to get them tight enough. OMC used this exact same way of attaching the flywheel to the crankshaft and the coupler to the studs. The nuts are supposed to have lock washers and you are supposed to tighten them to 40-45 ft lbs.

That would make sense

 

[Henry 68]

That would make sense

So i finally got to that 4.3 problem , for some reason the studs and nuts were tight but flywheel was loose . I redid all studs to torque specs added a special flywheel shim between flywheel and coupler and problems are solved . Thx for everyone,s help ... happy boating

 

[Lou C]

glad you got it and it was a simple solution in the scheme of things....

 

[Bt Doctur]

Should have ground the lip off the crankshaft first then the flywheel would stay tight