Siezed Mecruiser 120 engine

[wilsond3010]

so i picked up a old 1983 silverline but i've found the engine is seized

wondering what option out there for replacement.

 

[Howard Sterndrive]

Re: Ceased Mecruiser 120 engine

Re: Ceased Mecruiser 120 engine

http://regina.kijiji.ca/
post a wanted ad

you can put another used 120HP 2.5L or 140HP 3.0L long block from an OMC or Mercruiser

or you can buy a new 3.0 from a place like http://www.michiganmotorz.com/

or rebuild it yourself

or have it rebuilt locally

or simply try to unseize it... might just be stuck rings. There are some $10 solutions at the auto parts store that are sometimes worth a shot. other times compression never comes and you're only out another $10

are you sure it's the engine that's seized? could be gimbal bearing or the outdrive.

 

[wilsond3010]

Re: Ceased Mecruiser 120 engine

Re: Ceased Mecruiser 120 engine

my understanding they couldn't crank it at all with a wrench or hand

also when they removed the spark plugs they were rusted up

will try and get more details tomorrow

Is there a car engine i could use instead

 

[wilsond3010]

Re: Siezed Mecruiser 120 engine

Does anyone know if there is a car engine i could use for donor parts or replace it with instead

I did find another used mercruiser engine but the drive shaft is gone

i believe mine is ok but how do i tell if compatible i know mine is around a 1983

 

[tschmidty]

Re: Siezed Mecruiser 120 engine

There is no 3.0 car engine, you need a mercruiser.

 

[zbnutcase]

Re: Siezed Mecruiser 120 engine

Yup, no car replacement, best bet is just keep looking for a used one as there are plenty of 'em out there.

 

[wilsond3010]

Re: Siezed Mecruiser 120 engine

ok thanks.

Was wondering cause when i got it someone had a GM head sitting like they were going to try it.

And since it's a 2.5L 4 cylinder wondered if the block was a Iron Duke

I guess the other question would be. is the older or newer Mercruisers 120 Compatible to completely swap out with this one to connect to the outer leg

Forgive all the questions i'm a boat newbie

Also got a chance for a

6 cyl chevy engine that was used to power an OMC outboard drive. They are rated about 165 HP would it work for me

 

[wilsond3010]

Re: Siezed Mecruiser 120 engine

could i swap in a

1971 MerCruiser Marine 165 hp motor with stern drive leg

or would i have too much issues

 

[Howard Sterndrive]

Re: Siezed Mecruiser 120 engine

sounds like you're doing a lot of internet shopping before you've diagnosed anything.
Go out and twist some wrenches and find out what you have to work with.

Pull the drive off (15 minutes) and try turning the engine.

A month ago you posted it was cranking over....now it's seized?

 

[Howard Sterndrive]

Re: Siezed Mecruiser 120 engine

I did find another used mercruiser engine but the drive shaft is gone

there's no part of a mercruiser engine called a driveshaft.

you can d/l the manual from the adults only sticky here at iboats and familiarize yourself with some of the systems and how it all connects.

 

[Fishermark]

Re: Siezed Mecruiser 120 engine

could i swap in a

1971 MerCruiser Marine 165 hp motor with stern drive leg

or would i have too much issues

The biggest issue is that it is longer. I just did this on a boat and I believe it to be a lot of work for very little gain.

Your best bet is to find a 3 liter engine to replace the 2.5. They may only be rated at 20 hp different, but I have been in a boat that went from a 3 liter to a 2.5, (140 to 120), and there was a HUGE difference. The change to a 3 liter is very simple compared to going to a straight six.

 

[oldjeep]

Re: Siezed Mecruiser 120 engine

Pour a cup of Dextron trans fluid into each plug hole and let it sit for a few days. Then try to turn the motor with a breaker bar (plugs need to stay out). ATF eats rust and sometimes if you are lucky you can resurrect a stuck motor. Nothing really to lose at this point.

If it does come unstuck then make sure to change the oil and prime the motor with a drill to get oil to all the bearings. Then you can just suck the atf out of the cylinders with a siphon pump before attempting to start. If you leave all of the atf in the cylinders you will bend something.