1969 Mercruiser 120 stuck

[weinz90]

I just bought a 1969 Silverline with a mercruiser 120 I/O. I am new to the boating scene but I am a master tech at a Chevy dealer. The motor is stuck, im not sure if its just the rings rusted to the cylinder walls or if its actually locked up. Long story short, can I use an automotive GM 2.5L overhaul kit or do I have to use a marine specific kit?

I have been looking around and cannot find anything internal engine related on the internet.

Any and all help is greatly appreciated!

Thanks
Ryan

 

[dubs283]

Re: 1969 Mercruiser 120 stuck

try pulling the drive and see if the motor turns

the gm auto 2.5L is a different motor than the gm marine/industrial 2.5L and will not work for your application

 

[weinz90]

Re: 1969 Mercruiser 120 stuck

Pulling the drive?

 

[elkhunter338]

Re: 1969 Mercruiser 120 stuck

I agree pull the drive, also pour some engine oil down each cylinder and let it sit. If the rings are stuck this might free them. If it does start the engine with water and let the engine come up to temp and run it for awhile. Do a compression test on all cylinders and see what you have.

 

[ziggy]

Re: 1969 Mercruiser 120 stuck

Pulling the drive?

to see if it's the engine that won't rotate or if it's the drive that won't turn, thus preventing the engine from rotating.. you can find out how to pull the drive here... it's not to hard to do either... be sure it's in fwd..

 

[weinz90]

Re: 1969 Mercruiser 120 stuck

The engine is not hooked up to the outdrive, I just picked it up tonight. The out drive seems to be in great shape, The boat is a complete basket case which is why I only paid $200 for it. It seems like everything is there just not hooked up. I tried turning the engine over by the crank pulley bolt.

 

[littlebookworm]

Re: 1969 Mercruiser 120 stuck

First of all, I suggest you pick up the service manuals for the engine and the drive. Some are available for free on the internet; you'll have to do some searching. It's a good chance the engine is shot. I doubt very much that is was winterized properly so quite possible the engine is cracked somewhere. If so, you'd need to replace it. Marine engines have different freeze-out plugs, head gaskets, camshafts, distributors, starters, carbs, air filters/flame arresters, fuel pumps, alternators, and intake and exhaust manifolds than auto engines. You must used the correct parts. Some reading about marine engines, and in particular this one, is important so you'll know what you should or should not be doing. You need to pull the head off and see what's doing in the cylinders. In all likelihood, it won't be good. You then need to see if you can find a used or rebuilt engine to fit. Then you need to decide how much money, time, and energy you want to put into this project. I've done it with bigger boats than this. It's fun, frustrating, expensive, and rewarding. Good luck. Hy

 

[weinz90]

Re: 1969 Mercruiser 120 stuck

Thanks for all the information. I ordered the service manual and should be here in the next few days. Im looking for a project to keep me busy till next summer.

 

[DocR]

Re: 1969 Mercruiser 120 stuck

Wish I could help you with your "stuck" motor, but I am not a tech at anything. You sure are lucky that you are a "master tech at a Chevy dealer." My tip of the day is, "Stay on dry land".

 

[ziggy]

Re: 1969 Mercruiser 120 stuck

weinz90, check yer pm inbox...

 

[Don S]

Re: 1969 Mercruiser 120 stuck

Thanks for all the information. I ordered the service manual and should be here in the next few days. Im looking for a project to keep me busy till next summer.

Hope you didn't order a Clymers or Seloc, they are just aftermarket manuals more suited for knee pads than use as a manual.
Go to the link below, and you can download (for free) the OEM Mercruiser manual for your engine and outdrive.
Huge file, so give it time to download.
http://www.4shared.com/document/ozc1_97A/Service_Manual_01.html

 

[Doernuth]

Re: 1969 Mercruiser 120 stuck

I feel for you, I just took one of my 1977 Merc 165/Chevy 4.1 L Inline 6's to the engine builder for a rebuild for exactly the same reason.

Have you pulled the drain plug on the block? if you did and water drained its probably a cracked block and you need a new one. Get the casting number off of the block and you can use the same block from a car/truck engine as a base.

Keep us informed of the situation.