1986 Marlin / Model MCM 140 hp engine 181 CID

[DayRyder]

Hello,
New to the site I have inherited this 4 cyl stern drive boat w/ mercruiser 140 hp and the engine is siezed. I have removed the oil filter/ cut open and sure enough metal shavings were deposited in the cracks of the filter. Looking to replace the motor and in need of help. I can't seem to find what year, model and car that has the same engine? From what I have read it's a Chevy, just don't know which is compatible? Does anyone know?
Thanks anything would help.

 

[Scott Danforth]

The 3.0 liter NEVER came in a car. Its an industrial/marine only motor. It is a very common boat motor. Find a donor boat with rotton transom ( usually listed as free boat)
Look for a 1990 or older

 

[DayRyder]

Thanks for the tip Scott, is there anything specific I would need to ask about the engine? Say I was looking at a GM dismantler to swap a motor? Is that even possible? I'm also wondering how much I should spend without overpaying?

 

[Scott Danforth]

can you turn a wrench? do you understand righty tighty - lefty loosy. if so, swap it yourself

however first and foremost with your 30 year old boat. check for rot in the stringers and transom.

once you determine that the hull is infact rot free and sound, then proceed on to the motor

remove outdrive (about 1/2 hour)
disconnect electrical, fuel, cables and exhaust (about 1/2 hour)
disconnect motor mounts from stringer bed and transom shield (about 1/4 hour)
use cherry picker or other device to lift motor from boat (about 1/4 hour)

with outdrive off, inspect the u-joints, ginbal bearing, etc. replace the bellow and the raw water pump

installation is reverse, however prior to installing outdrive, you need to align motor and drive.

and no, you can not swap a motor without removing the drive because you need to align the motor and drive.

 

[DayRyder]

thanks for the help greatly appreciated.

 

[Scott Danforth]

depending on where you are located, you can usually find a complete 3.0 driveline in a boat that has a junk hull for about $800 plus/minus. I search craigslist for "free boat" and "free trailer" usually there is a boat with a 3.0 that someone bought, left outside in the elements to rot and realized they killed it and now want it gone.

 

[Bondo]

you can usually find a complete 3.0 driveline in a boat that has a junk hull for about $800

Ayuh,..... A runnin' bobtail 3.0l on a pallet is worth a Grand here, all day long,....