couple questions on this old boat 120HP I/O OMC

[oceaninabox]

I bought this old boat from this older fellow who is about to pass away from cancer. Anyway got a steal on the boat and it does run. However I need to know any insight you can give about the shift knob. What is the pull out knob on the shift for? I tried it both in and out and it didnt do anything. The boat was still able to be put into gear. I thought maybe it was a neutral switch of somekind. The second question. He had not had the boat out in several years as he has been sick. I took the boat out today and man it fired right up. Purrred like a kitten, but when I put it under a load it wanted to bog down and cut out. At one point I did mess around with the carburator levers and it semi resolved the problem in fact it flat out got up and went for a while them repeated the same symptom and bogged down. Do you think it just needs to have the carb cleaned out or rebuilt perhaps? It is a 120HP OMC sterndrive 1973. Seems like the fellow took good care of it, just needs some TLC. Any insight would be appreciate.

 

[NW Redneck]

Re: couple questions on this old boat 120HP I/O OMC

That knob is the neutral switch or 'lockout knob'. I have the same controller on my 1975. If it still goes into gear with the knob out then you have a problem. Pulling the knob out should prevent it from engaging forward or reverse when moving the throttle lever so you can adjust your idle speed for starting and warming up.

As for the running issues, it probably just needs a service and tune-up. Being that the boat has sat for a long time the first thing I would do is drain the old fuel and get some fresh stuff. Then check and/or replace the fuel filters, inlet screens, and pull the bowl off the carb and see if there's any gunk/water/varnish in there. If any, I would rebuild the carb. Check the ignition side too, Probably needs new plugs, wires, cap/rotor and points. Add an oil change and you shold be good to go!

 

[libellav15]

Re: couple questions on this old boat 120HP I/O OMC

good luck with the boat and all that.....

BUT was there really any need to even mention the poor old owners bad health issues? Let alone revel in the fact that you got a 'steal' on the boat as a result of them??

 

[superbenk]

Re: couple questions on this old boat 120HP I/O OMC

Also check if there is an anti-siphon valve at the fuel pickup on the tank. If there is, it may need to be replaced. I had the problem where that valve was sticking somehow & impeding fuel delivery at higher RPMs. Removed the old one and the boat runs like a champ now. (Note, I've also done all the other things mentioned above including rebuilding the carb & replacing the fuel pump, coil, rotor, distributor cap, plugs, wires, points, condenser, fuel line, etc. All good advice.) Also check gap, dwell & timing are set properly.

 

[Blk-n-Blu]

Re: couple questions on this old boat 120HP I/O OMC

Here is a link to a free service manual. Click on the "blue download button"
http://www.4shared.com/file/zF-DZrvB/1964_-_1986_OMC_Sterndrive_Man.html

 

[oceaninabox]

Re: couple questions on this old boat 120HP I/O OMC

That knob is the neutral switch or 'lockout knob'. I have the same controller on my 1975. If it still goes into gear with the knob out then you have a problem. Pulling the knob out should prevent it from engaging forward or reverse when moving the throttle lever so you can adjust your idle speed for starting and warming up.

As for the running issues, it probably just needs a service and tune-up. Being that the boat has sat for a long time the first thing I would do is drain the old fuel and get some fresh stuff. Then check and/or replace the fuel filters, inlet screens, and pull the bowl off the carb and see if there's any gunk/water/varnish in there. If any, I would rebuild the carb. Check the ignition side too, Probably needs new plugs, wires, cap/rotor and points. Add an oil change and you shold be good to go!

Can the knob be cleaned and adjusted or will the whole shifter need to be replaced?

 

[oceaninabox]

Re: couple questions on this old boat 120HP I/O OMC

Here is a link to a free service manual. Click on the "blue download button"
http://www.4shared.com/file/zF-DZrvB/1964_-_1986_OMC_Sterndrive_Man.html

Thanks for the manual link. Question for anyone. When I am talking to my mechanic about ordering parts do I simply identify the motor as a '73 OMC 120HP sterndrive?

 

[superbenk]

Re: couple questions on this old boat 120HP I/O OMC

Thanks for the manual link. Question for anyone. When I am talking to my mechanic about ordering parts do I simply identify the motor as a '73 OMC 120HP sterndrive?

Good luck finding a mechanic who will work on OMC. You might find one who's been around for awhile that will do some stuff, but OMC has been out of business for a very long time & most mechanics won't touch them. Best to get used to looking for parts yourself on eBay, here on iBoats, Google, etc.

Bombardier has an interactive parts catalog online you can find most of the original OMC part numbers for that you can cross-reference with Sierra, GLM, Mallory, etc. 3rd party brands.

http://epc.brp.com/SiteMods/BRP_Public/BRP_Public_Login.aspx

Just click "View Parts Catalogs" -- you don't have to enter your email if you don't want to -- select 'Stern Drive' from the drop-down menu & dig down until you find your model engine/outdrive.

 

[NW Redneck]

Re: couple questions on this old boat 120HP I/O OMC

Can the knob be cleaned and adjusted or will the whole shifter need to be replaced?

I'm not sure, as I have never had to take mine apart. (Knock on wood )

You will have better luck finding parts if you have the model and serial #'s of your motor or drive. For the motor there should be a plate attached to the starboard side flywheel housing above the starter motor, and for the drive it should be below the starboard side trunnion cap.

Use your m/n and the site posted by superbenk and you should be able to ID any part you need.