Merc 305 replacement

[Chuck08]

I was a (fill in your own words here) and cracked the block on my 305. I was thinking about using jb weld since it appears to be just the water jacket. However, wanting to be able to keep the boat for a while or sell it I want to replace it. I was going to get a long block and use a forklift boom to swap motors but I can not afford a long block and then shipping to Ohio. I am currently thinking about getting a 305 off craigslist putting in the cam, carb, and spark arrestor, from my current motor and putting a heat exchanger to run coolant through the motor instead of raw water. Would there be anything else I would have to do to make this work?

 

[Bondo]

Ayuh,.... Is there any water gettin' into the oil, when ya run the motor,..??
If the cracks are only to the outside, 'n not into the oil,... JB Weld can get ya many more years of service outa it,....

A pickup motor for a junkyard can work, with all the bolt on accessories off yer old motor,... I wouldn't worry 'bout the cam,....
Closed coolin' is fairly expensive, 'n ya still gotta winterize it,...

 

[Chuck08]

so far I had not seen any oil in the water and no water on the dipstick. therefore I believe its just the outer water jacket. I would like to pull the motor anyway to jb weld it this winter in my warmer garage. any tips on how to check the will hold when the motor is outside the boat?

 

[Bondo]

I would like to pull the motor anyway to jb weld it this winter in my warmer garage. any tips on how to check the will hold when the motor is outside the boat?

Ayuh,.... Plug off, 'n isolate the blocks coolin' passages, 'n pressurize with air,....

You'll Hear the leaks, follow the sound,....

15 psi is plenty, 'n the block wants to be drained 1st,....

 

[Scott Danforth]

LKQ pick-a-part gets $300 for a truck motor in Ohio

you dont say what year your 305 is. however I would put in a 350 if the 305 is toast.

 

[Chuck08]

its a 1994 boat with what looks to be the original motor. the 305 had plenty of power and everyone wants an arm or a leg for a 350 If I can pick one up cheap and reliable I may go that route, but I may have to change other things too.

 

[Scott Danforth]

if you stick with a 1986-1995 motor, you can bolt on all your stuff (intake/exhaust/accessories/etc). if you pick up a 1996 or later motor you need a different intake)

350's are same price as 305's which are the same price as 454's at the LKQ pick-a-part.... all carb'ed motor are one price, all EFI motors are a different price, all Diesels are another price. they dont price by displacement

https://www.lkqpickyourpart.com/loca...on-257/prices/

I was wrong, its $200 in Ohio. $300 in Florida

 

[Chuck08]

I actually just found out the max hp for the boat is 175 through the boat specs part of this website. I feel like the 305 was well above that. Could this become an issue if I put another 305 in, a 350?

 

[Bondo]

Could this become an issue if I

Nope,....

 

[kenny nunez]

Chevy engines tend to freeze crack under the intake as that appears to be the thinnest area of the block. Maybe your engine is just cracked on the outside, you may have lucked out.

 

[chevymaher]

I actually just found out the max hp for the boat is 175 through the boat specs part of this website. I feel like the 305 was well above that. Could this become an issue if I put another 305 in, a 350?

Max HP rating was for outboards only. I went through this looking for a rating for mine. Inboards for whatever reason have no HP rating. Mine is listed as a 120 max HP in the iboats resources. But I have the original sales flyer and it came equipped if you ordered it with a 260 HP 350.