1981 Mercruiser 120 HP 2.5L Service Manual

[debo9184]

Hi all,

I'm new to this thread, but I have a coupler issue to fix on my 1981 120 HP Mercruiser 2.5L with Alpha outrdive. I live in Ohio and I took my boat to Lake Berlin a few months back before it was freezing ... and as soon as I get out of the no wake zone I give it some throttle and all of a sudden I lose all propulsion. I was later told if I would have kept the boat running I probably would have over heated it (I'm assuming the propeller doesn't spin if your coupler goes out??) but once I wasn't able to move someone pulled me back to the dock and I trailered the boat to the local marina. While there I told him what happened so with the boat turned off he put the throttle in forward position and came to the back of the boat and spun the prop. He then got in the boat and put his hand what look like behind the motor and had his assistant spin the prop. He said the coupler would need to be replaced and the cost would be about $1200 including labor. I only payed $1200 for the boat so I figured I would attempt to replace this myself, knowing that the outdrive and engine will both need pulled. I have already removed the outdrive and I have an engine lift at my house but I have not started to remove the engine. I seen the service manuals were posted in the "Adults Only" thread sometime back but have now been removed. I was hoping someone could help me to find out where I can find a manual as well as tell me how much trouble i am getting myself into by attempting to fix this myself. I know I will need an alignment tool when putting everything back together, but that is the only special tool I am aware of at this time.

Thanks in advance for the help!

 

[littlebookworm]

Re: 1981 Mercruiser 120 HP 2.5L Service Manual

Sorry to hear about your problems. If you go to the Chaparral Owners Forum @ yahoo.com, you'll find a number of Mercruiser and Alpha manuals free for the download. I'm not sure that you'll find one there, but it's worth a shot. If not, try the SeaRay Owners Forum. I think that site posts manuals as well. Good luck. By the way, the replacement isn't that complicated. Just remember to re-align your engine after you get it back in the boat and before you re-install the outdrive. You'll need an alignment tool (basically a fittted steel shaft of set varying diameters). You can find one on eBay. Hy

 

[Alpheus]

Re: 1981 Mercruiser 120 HP 2.5L Service Manual

1200 bucks! You need manual #3 I think. That is one that I dont have but Im sure someone will be along with a link to a download.

Did you smell or see any smoke or smell rubber burning while this was going on?

the throttle in forward position and came to the back of the boat and spun the prop.

Was he able to spin the prop in both directions?

This could also be a bad shift cable...

 

[Don S]

Re: 1981 Mercruiser 120 HP 2.5L Service Manual

You actually need two manuals for your engine/drive.
#3 for your engine. It's here and #4 for your outdrive, it's here.
After you get the engine back in the boat, you WILL need an alignment bar to realign the engine to the gimbal bearing lots of information on that here
You should also replace the rear mounts, when they go bad, you will loose a coupler.

 

[fat fanny]

Re: 1981 Mercruiser 120 HP 2.5L Service Manual

I hate to hear your problems and do hope you resolve them on your own because for 1 if you were in Berlin a couple of months ago you are crazy (no- offence) because the water level there was dropped below tthe safe level for boating @ the end of August and 2nd you actually met Dutch and if you can afford his work man I evy you but he is the best tech in the area but he does have the best parts prices around just go in knowing what you want and he'll hook you up. If you need any help let me know just PM me I have a couple of the tools you'll need for the job. I live in Alliance.