2012 4.3 motor in 2004 boat - harmonic balancer?

[670hoth]

I am trying to put a 2012 4.3 truck motor in a 2004 boat and there is an issue with the harmonic balancer. The 2008 and up 4.3s have a different timing chain cover which sticks out more and the 2004 harmonic balancer and hits the timing mark tab, crank position sensor, and possibly the front seal. I cut down the timing tab and sensor (not used with 2004 distributor ignition) so they clear but it still seems like the balancer may be touching the seal. Unfortunately, the 2004 balancer must be use or you will have problems with belt alignment, fresh water pump mounting, etc.... Has anyone ever faced this before and/or have any ideas? Thanks

 

[Fun Times]

For the marine side of the GM 4.3 I recall seeing a parts design change type bulletin sometime right around 2007-08ish..Though I don't recall the details of it...It seemed the 07 and under wasn't going to retrofit onto the 08+ engine models.

So kind of knowing that led me to the following info for you to start off with,

As of the 2013 model year, the 4.3L was still in production although the distributor was eliminated in the late 2000s where a coil-on-plug ignition system (using a 58x crankshaft position sensor based on the GEN IV LSx) was phased in. This resulted in a new design timing cover with a wider bottom flange, making it incompatible with the 1996-06 LU3/L35. The only vehicles using the 4.3L by that time were the GMT900 light duty trucks and vans.

As of March 7, 2014, the last 4.3L engine rolled off the line at Romulus Powertrain. Chevrolet Performance still lists the LU3 motor in their product catalog. Mercury Marine, which sells its engines under the MerCruiser brand, developed a 4.5L V6 based on the 4.3L architecture using similar dimensions.
https://en.wikipedia.org/wiki/Genera...2%B0_V6_engine

While I doubt you do, I'll just through it out there while we're here just in case....Being your engine is a 2012 year model out of a truck, be sure to know if the engine is or isn't a new for 2012 engine design called the LV3 as it could make things even harder to match up then what you're experiencing now.

LV3
4.302 l (262.5 cu in) LV3 V6 is a new engine announced by GM at the end of 2012. GM considers this a new engine design which inherits from its predecessors its displacement, 2-valve pushrod valvetrain, 90-degree cylinder angle, and 4.400 in (111.8 mm) bore centers. It is based on the fifth generation LT engine and includes the same features such as direct injection, piston cooling jets, active fuel management, variable displacement oil pump, continuously variable valve timing and aluminum cylinder heads and block. The engine is SAE certified to 285 hp (213 kW) at 5300 rpm and 305 lb⋅ft (414 N⋅m) at 3900 rpm on regular unleaded gasoline and 297 hp (221 kW) at 5300 rpm and 330 lb⋅ft (450 N⋅m) at 3900 rpm on E85. Emissions are controlled by a close-coupled catalytic converter, Quick Sync 58X ignition, returnless fuel rail, fast-response O2 sensor.[SUP][11][/SUP] It was launched in the all-new 2014 Chevrolet Silverado 1500 and 2014 GMC Sierra 1500.[SUP][12][/SUP]

If no luck on boating forums for detailed info of making something work then maybe try a GM truck forum or try to visit a knowledgeable GM dealer parts guy...Good luck.
Just re-read your post and I realized you knew that already regarding the year/design change....Wish I could help you better.

 

[Scott Danforth]

either get the correct damper or find a pre '07 motor. you cant mix and match different generation of 4.3 parts.

 

[670hoth]

For the marine side of the GM 4.3 I recall seeing a parts design change type bulletin sometime right around 2007-08ish..Though I don't recall the details of it...It seemed the 07 and under wasn't going to retrofit onto the 08+ engine models.

So kind of knowing that led me to the following info for you to start off with,

While I doubt you do, I'll just through it out there while we're here just in case....Being your engine is a 2012 year model out of a truck, be sure to know if the engine is or isn't a new for 2012 engine design called the LV3 as it could make things even harder to match up then what you're experiencing now.

If no luck on boating forums for detailed info of making something work then maybe try a GM truck forum or try to visit a knowledgeable GM dealer parts guy...Good luck.
Just re-read your post and I realized you knew that already regarding the year/design change....Wish I could help you better.

Hello Fun Times, It is not the new LV3. It is an LU3 but the 'LU3' designation carries through from around 2000 to 2012 including both distributor engines with V belts through distributorless engines with serpentine belts which started in 2007-08ish. Please see my next post with info on where I am at now. Thanks for the help.

 

[670hoth]

So I found another post where a guy machined the ridge off the 2012 (08 and up) harmonic balancer so it would accept his old style v belt pulley/fresh water pump. I did not feel comfortable with this because the ridge was there to assure the pulley was centered properly on the new balancer. On the old 2004 balancer it is centered via the center hole. Because of this I did some more comparisons of the two balancers and came to the conclusion that the shaft length that goes into the engine is the same on both and therefore the seal/balancer shaft fit was the same. Since I filed the timing tab and position sensor back on the new style aluminum timing cover already there were no issues using the old balancer and my original pulley/freshwater pump assy. The one remaining problem is the water pump. The old one had another hole below the bottom right bottom mounting hole that simply sealed to the surface of the block through the gasket. The front of the new engine is machined differently so the bottom hole which is open into the water inlet will not seal against the new block. I am going to tap the hole in the water pump and install a brass plug deep into the hole. I will also have to grind a bit off the water pump casting on the side in the same area because of interference against the new aluminum timing chain cover and then the water pump should go on fine. At this point I am pretty sure I am home free. Honestly, the correct thing to do would be to convert the engine to the serpentine belt set-up like the 2008 and up Volvo 4.3 GLs have. I do think I could use the steering pump and alternator bracket that came with the truck engine to do this as well as some of the serpentine pulleys but I would have to buy some new pulleys, a tensioner, and new serpentine belt, and fresh water 'holder' bracket that keeps it from rotating at a minimum. I may also have to buy a new freshwater pump but I am not sure. I am also not sure if I could use the 2012 truck engine water pump or would have to buy a 'marine' unit. All of these things would cause me to loose good boating time this summer and cost a decent amount of money. I am going to stick with everything and keep this unit a V belt set-up even though it will not be 'standard' going forward. If anyone that may own the boat after me ever changes the water pump they will have to buy a unit to fit a 2004 (up to 06), tap and plug the extra hole, and grind the pump a bit in the same area. Any other thought or recommendations would be greatly appreciated. Thanks