4.3 Mercruiser engine block Cracked- Can you replace with a regular automotive engine

[pgibson]

Hey...I got my first boat last year. Its a 1988 Lund Baron 2100. IT has the 4.3L Engine. I asked a friend last year how to winterize it...I guess he was not correct! Water is getting into oil. Cracked block. I have a used car dealership so have ready access to automotive engines. Are you able to replace with an automotive 4.3L Engine? or better yet are you able to replace with a 5.7L Chevy V8? If so what all needs to be done to make it work properly. Thanks you all in advance for your advice and knowledge.

Paul G

 

[Tubingluvr]

Re: 4.3 Mercruiser engine block Cracked- Can you replace with a regular automotive en

Hey...I got my first boat last year. Its a 1988 Lund Baron 2100. IT has the 4.3L Engine. I asked a friend last year how to winterize it...I guess he was not correct! Water is getting into oil. Cracked block. I have a used car dealership so have ready access to automotive engines. Are you able to replace with an automotive 4.3L Engine? or better yet are you able to replace with a 5.7L Chevy V8? If so what all needs to be done to make it work properly. Thanks you all in advance for your advice and knowledge.

Paul G

I do not recommend replacing your marine engine with an automotive engine.....you would be lucky if it lasted one season.....for one marine engines run at much higher rpm's.....I believe yours runs between 4400 and 4800

 

[CobiaXL]

Re: 4.3 Mercruiser engine block Cracked- Can you replace with a regular automotive en

Are you able to replace with an automotive 4.3L Engine?

Yup

 

[cr2k]

Re: 4.3 Mercruiser engine block Cracked- Can you replace with a regular automotive en

Generally people have been having good luck using a 4.3 from a pick-up. You still need to use all the original Marine parts like fuel pump/carb. starter, manifold, distributor and alternator. Replace core (freeze) plugs with brass.

If internals are good go with block only swap for best reliability.

Gotta remember a vehicle engine is designed (cammed) for broad range rpm use, where as Marine is set up for duration running at cruise rpms.
PU engine has torque curve closer to marine then car.

Do a search for 4.3 and you find several threads on this swap.

 

[MSRTBUDWISER]

Re: 4.3 Mercruiser engine block Cracked- Can you replace with a regular automotive en

Are you sure that you have a cracked block? If you are just assuming, I would run a compression check on your engine. You may just have a blown head gasket and that would run you much less that a new motor.

 

[Capn G]

Re: 4.3 Mercruiser engine block Cracked- Can you replace with a regular automotive en

I replaced my 4.3L with a Chevy truck long block 3 years ago. I swapped out water pump, manifold and carb and dropped it into my Stingray. (didn't align it, gimbal problem now) and I got rid of the electronic stuff and switched out the distributor to an HEI. I had bought a new ECM (for sale by the way) that I never installed. The only trouble I had with this setup was the first year. I had run it without a thermostat, so a mechanic friend of mine said that I wouldn't develop full horsepower unless engine temp came up, so I put in automotive thermostat.... problem with that was after I shut down the engine, it continued to spit and sputter for a few minutes and finally died. Some dock-side surgery to remove the thermostat, another test-run and she shut down like normal. Did a little research and found the reason for the run-on... The thermostat allowed the engine temp to get too hot, and on shut down, the cylinders were still hot enuf to detonate the remaining gas... and since the carb is bowl/float, each detonation would suck more gas into the cylinders and it spit and sputter to either no gas left to pull or temp cooled enough to halt detonation. The solution was to put in a lower temp thermostat than a normal auto engine. Works like a charm now... no problem... if memory serves, it's a 140 degree Tstat...

I screwed up and didn't read about installing and aligning the engine to the outdrive, now I'm paying by replacing gimbal and bellows.... and having to buy tools to ensure it's done right. If you think "auto engine" don't forget the "boat" stuff as well.