Older Mercruiser wont turn over

[Pst76]

Trying to get an old Mercrusier thats on a House boat to turn over..Its a Model 120 s/n 4648598. Its on a friend of mines boat and has a duel engine set up. The other one runs like a top. Starter selonoid chatters when you put power. All connections are clean and New battery. Pulled the plugs and it does the same thing. Trying to determine a way to turn the motor over by hand to see if motor might be seized. Tryed turning with the belts but only the water pump and alternator would turn belt slipped arount the crank pulley. With the way the motor is mounted cannot get to the center of the crank shaft. I'm thinking two possible issues. 1- starter is messed up as I would think if motor froze ot would still engage into the flywheel but lock up? The other is the engine is seized? Any tricks or suggestions as to best way to try and turn by hand? I'm going to pull the starter next as I dont want to pull the head and find out its fine inside. Oil on the stick look clean, no water intrusion how ever in pulling the plugs, # 4 cyl plug had a bit of rust on the electrode. Motor has not run in 3 yrs.

Open to suggestions.
Thanks in advance

 

[Watermann]

Re: Older Mercruiser wont turn over

First off oil fog the cylinders good since you found some rust on the electrode of the plug, you don't want those rings to run in some dry surface rust in the cylinder and hang up when she does go. If it were froze up, there should be a loud bang when the starter drive engages the flywheel and it doesn't turn. It sounds more to me from what your describing that the solenoid isn't engaging the starter.

 

[Pst76]

Re: Older Mercruiser wont turn over

First off oil fog the cylinders good since you found some rust on the electrode of the plug, you don't want those rings to run in some dry surface rust in the cylinder and hang up when she does go. If it were froze up, there should be a loud bang when the starter drive engages the flywheel and it doesn't turn. It sounds more to me from what your describing that the solenoid isn't engaging the starter.

Thanks, Going to pull the starter tonight if I get time and start there. We put Marvel Mystery oil and some PB blaster into the cyl's through the spark plug holes then finger tightend the plugs so it can sit.

 

[Don S]

Re: Older Mercruiser wont turn over

Pull the starter off, and use a big screwdrive to bar the engine over using the ring gear teeth on the flywheel.

 

[Pst76]

Re: Older Mercruiser wont turn over

OK follow up.. Way more issues with this one than I bargined for. Here what we did . Pulled spark plus. Cyl 4 plug had rust all over the electrode and top of the cylinder head looks the same from what I could see with shining a flash light into the plug hole. Removed the started which turned out to be a chore itself trying to reach the bolts. Starter seems questionable. the solinoid seemed to be pretty beat would not always fire the starter motor. Tryied to turn the motor with a screw driver into the flywheel, Plugs out and got no movement. Looking down toward the transom was able to see the gimble bearing and shaft area with a flash light. Completely covered with rust..The house boat is in the water so pulling the out drive as it stands is out. I let the owner know this was more than I was willing to tackle as I was just asked to see if it might be a simple fix. Suggested he get with a local marine mechanic and take that route. Thanks for the feed back on trouble shooting this one.