1994 Mercrusier 4.3l engine compatability

[skinaked51]

Hello all. I'm sure this has been beat to death. But I really need some direction. I have a 94 bayliner with the merc 4.3l engine. It has a cracked block in the lifter valley, I pulled the intake manifold and it looks good but the valley has 2 big cracks. I am looking to get a different engine for it. As I understand it there were 3 generations of this motor and I believe this is a gen 2. I have found several Chevy s10s in the 2001 to 2004 range. I am curious to know if the gen 2 and gen 3 blocks are the same. I am thinking of getting one from a truck and replacing head gaskets and using my marine heads and intake and accessories etc. Any help would be greatly appreciated

 

[Scott06]

Hello all. I'm sure this has been beat to death. But I really need some direction. I have a 94 bayliner with the merc 4.3l engine. It has a cracked block in the lifter valley, I pulled the intake manifold and it looks good but the valley has 2 big cracks. I am looking to get a different engine for it. As I understand it there were 3 generations of this motor and I believe this is a gen 2. I have found several Chevy s10s in the 2001 to 2004 range. I am curious to know if the gen 2 and gen 3 blocks are the same. I am thinking of getting one from a truck and replacing head gaskets and using my marine heads and intake and accessories etc. Any help would be greatly appreciated

The 96 and up use vortec heads with an 8 bolt intake. This will provide more power vs the earlier 12 bolt intake heads. Also later blocks will require use of an electric fuel pump.
thee are no such thing as marine heads. They are the same as truck heads. Only diff between truck and marine is head gaskets, circulation water pump, and core plugs. Some slight diff between marine cam and truck but many have used truck cam just fine

generally stripping a truck engine to long block and using marine intake, exhaust, fuel and electrical components gets the switch done

@Scott Danforth i think did a write up

 

[Scott Danforth]

As of today there are 8-10 different generations of 4.3.

Your current motor is a 93-95 vintage. Assume your intake manifold is trashed from the same lack of winterizing that killed the motor. Same for exhaust manifolds

The next generation of motors are the 1996-2000, 2001-2007, 2008-201x, and a few more after that

The 2001-2003 s-10s are a fine choice. You only need the long block, as all the other automotive bits won't be used.

As Scott mentioned above, swap the core plugs to brass, head gaskets to marine, get new marine circulation pump. And since the new motor is a vortec, you need a different intake anyway. Swap over your front accessories, rotating electrics, etc

 

[skinaked51]

As of today there are 8-10 different generations of 4.3.

Your current motor is a 93-95 vintage. Assume your intake manifold is trashed from the same lack of winterizing that killed the motor. Same for exhaust manifolds

The next generation of motors are the 1996-2000, 2001-2007, 2008-201x, and a few more after that

The 2001-2003 s-10s are a fine choice. You only need the long block, as all the other automotive bits won't be used.

As Scott mentioned above, swap the core plugs to brass, head gaskets to marine, get new marine circulation pump. And since the new motor is a vortec, you need a different intake anyway. Swap over your front accessories, rotating electrics, etc

Would I need to change the cam? If so, to my current marine cam? Or will an older gen cam not work in a newer engine? Also would my current carburetor set up work on the new marine intake? And would my current exhaust manifolds fit? They are good

 

[Scott06]

Would I need to change the cam? If so, to my current marine cam? Or will an older gen cam not work in a newer engine? Also would my current carburetor set up work on the new marine intake? And would my current exhaust manifolds fit? They are good

if the 4.3 is out of a truck leave the cam alone.

What is your current carb? 2 bbl or 4 bbl? Likely jetting would need to be changed for the vortec heads. If yo have a 2 bbl not a bad time to upgrade to 4 bbl.

Your current exhaust manifolds will work but I would be surprised if they aren't cracked too, unless someone drained them and forgot the block? Test with acetone first to make sure there are no cracks

 

[Scott Danforth]

Im of the mindset, the block froze, why take a chance killing the next block with potentially freeze cracked manifolds.

you could also put a 5.0/5.7 block in there, run the same accessories you have. you need a new intake and exhaust manifolds anyway.

 

[skinaked51]

Ok so I ended up finding a 2004 chevy s10 blazer. I just picked it up tonight. Has 102000 miles so not too bad. I'll have to get it pulled out and stripped down. My carb is a 4 bbl, what will I need to get that won't fit from my other motor? And what am I looking for? 8 bolt intake for a 4bbl? Will all year exhaust manifolds fit? And water pump?

 

[Scott Danforth]

You need a vortec marine intake. All 4.3 exhaust manifolds are the same

 

[skinaked51]

Ok great. I do have another question. So this boat was ran at the first of the season before realizing the motor was cracked and full of water. The Outdrive sucks the water In, how do I winterize just the outdrive? Where I'm not able to run the motor or drain it?

 

[Scott06]

Ok great. I do have another question. So this boat was ran at the first of the season before realizing the motor was cracked and full of water. The Outdrive sucks the water In, how do I winterize just the outdrive? Where I'm not able to run the motor or drain it?

Outdrive will self drain water. Change the gear oil in it. If you find evidence of water in gear oil pressure test the od to find seal leaks

 

[Scott Danforth]

You have to pull the outdrive to pull the motor. Just put the outdrive in the basement

 

[skinaked51]

Thank you for the responses. What about the distributor? The 94 was cap and rotor, the 2004 looks different. Is it an electronic ignition? If so what will I need to keep for it?

 

[jimmbo]

Myself, I would ditch the Truck Cam, and get the Marine Grind.
In my Eyes, 'Close', is good enough for Horse Shoes, Grenades, and Nuclear Weapons, but not Cam Grinds

 

[Scott Danforth]

Thank you for the responses. What about the distributor? The 94 was cap and rotor, the 2004 looks different. Is it an electronic ignition? If so what will I need to keep for it?

You ditch everything that is not the long block from the S-10

Your marine distributor will swap over fine. Your 94 should be Thunderbolt 4

 

[Bondo]

Myself, I would ditch the Truck Cam, and get the Marine Grind.
In my Eyes, 'Close', is good enough for Horse Shoes, Grenades, and Nuclear Weapons, but not Cam Grinds

Ayuh,..... Oem, to Oem, they're the same cam,.....