Help on a Mercruiser 120

[Jetmate492]

I bought a pontoon and the motor had a cracked block now I need to buy some parts for it. I have the serial number (B43397) but I don't know the year. Can anyone help me find out the year and maybe the best place to buy replacement parts?

 

[Silvertip]

Re: Help on a Mercruiser 120

You have a cracked block -- why aren't you looking for a rebuilt engine instead of parts. New parts on a cracked block means you still have a cracked block. Can't tell from your number what you have. Here is a reference but I think you need to check the numbers again.

http://www.marineparts.com/partspages/techhelp/TECH16.HTM

 

[Joshua Nichols]

Re: Help on a Mercruiser 120

the motor had a cracked block

Did you buy a new long block or something?

You didn't JD weld did ya:facepalm:

 

[Bondo]

Re: Help on a Mercruiser 120

Can anyone help me find out the year

Ayuh,... Motor, 'n drive parts are sold by Serial #s, Not by Years.....

What sorta parts ya lookin' for,..??

 

[Don S]

Re: Help on a Mercruiser 120

I have the serial number (B43397)

Your serial number is short a number, and I don't know if it's the first or last or one in the middle. All the 120's that had a B in them were between the years of 83 and 89.
Once you get the full number, you can check it against this SN to year file. http://www.4shared.com/document/TcRI4n4z/MCM_Model_year_SN_range.html

 

[zbnutcase]

Re: Help on a Mercruiser 120

Even with serial #, still gonna be hard to find an out of production engine for which there are damn little cores available for

 

[Bondo]

Re: Help on a Mercruiser 120

Even with serial #, still gonna be hard to find an out of production engine for which there are damn little cores available for

Ayuh,... But,.. the 140hp, 3.0l is a direct Plug, 'n Play replacement...

 

[Jetmate492]

Re: Help on a Mercruiser 120

Did you buy a new long block or something?

You didn't JD weld did ya:facepalm:

I have had good luck in the past welding up cracks on tractor blocks and a car or two. So I thought I might give it a try. The worst case scenario is I screw it up worse if that is possible. Attached is a picture of the Serial number on the engine. The only parts I am going to need is the gaskets for the manifold, water pump and exhaust elbow.




How hard would it be to convert to a 140hp? What is the cost of one? Thanks for your help.

 

[Joshua Nichols]

Re: Help on a Mercruiser 120

The bad thing about a boat engine is the internal crack from raw water freezing.. I have nickel welded up more than one or two tractor and pick up blocks in my day too.. It won't work on a internal water jacket crack... You will still end up with water intrusion.. You are talking about a external crack.. Caused by a bent pushrod failure or such.. Go ahead and give her a try.. You might get lucky and it fix her but likely not.:facepalm:..

Get ya a good rosebud, or better yet save some time.. Pick ya up a new longblock

 

[Bondo]

Re: Help on a Mercruiser 120

How hard would it be to convert to a 140hp?

Ayuh,... Like I said,..."the 140hp, 3.0l is a direct Plug, 'n Play replacement"...

Long block, for Long block swaps that is....

 

[muc]

Re: Help on a Mercruiser 120

S/N 0B433997


Warranty Period:
07/01/1986 - 07/01/1987

Best place for parts?
For the best parts, your Mercruiser dealer.
For the cheapest parts, iboats or some other internet source.

 

[alilley]

Re: Help on a Mercruiser 120

i have been dealing with the same issue here. i bought the boat knowing that it had a cracked block, hoping that it was just an external crack. After i got it all "patched up" and running top notch, got her out on the lake for a couple passes and it ran great. got her back home and changed the oil in it only to find water in it. i went back out next weekend with the fresh oil and was out about ten min. and oil again looked like a milk shake only much thinner. I got her back home pulled head off only to find a crack between 2 of the clyenders and a corresponding carack in the same place on the head as well as blown head gasket in the same spot. what i have learned from this is that wehn an engine is not winterised right it is going to break the block. once water freezes it becomes a very stron sold and does not compress so something has to give and it usually gives in more then one place.

honestly your best bet will be as other people have posted previously is to find you a new long block. i know they are not cheap but it will be the right way to go. i know you can get a hold of jasper engins and they will have you one (at least on the 181cid 3.0l) jsut do some looking around and you will find one.

 

[Jetmate492]

Re: Help on a Mercruiser 120

***UPDATE***
So I welded up the block and it didn't leak and no water in oil (after I replaced the impeller it ran for about 15mins) but the motor ran hot so I did some reading on here and found it had a impeller that probably need to be replaced. took the foot apart and replaced it but now I cant get it to go back on and change gears(I didn't loose the washer). I have read the sticky post on here but I cant get it to go back on right!!!!!! Is there a easy trick to it? Please help I have spent the better part of two days on fixing the foot.

 

[Bondo]

Re: Help on a Mercruiser 120

Is there a easy trick to it?

Nope,... No "Easy Button"....
Keep everything in Forward...
When you get everything lined up, it'll slide Right into place...

 

[Jetmate492]

Re: Help on a Mercruiser 120

When I turn the shift shaft which way is forward? I have been turning it CCW is this right?