Omc 1984 2.5

[shotblater1]

After buying my latest project boat a 84 Renken 18.8 bow rider with a 2.5 omc I/O i would like to here the pros and conns of this engine. It runs great and seems to have been taken care of. I read several posts on these engines and would just like to see some coments on what i should lookout for and possible problems i may come across. complete rebuild is in progress. stringers transom and deck to start off.

 

[Howard Sterndrive]

Re: Omc 1984 2.5

pro- probably the most reliable and simplest boat engine in the history of boats
pro-parts available anywhere

con- it only makes 120HP, kinda brutal in a 19 foot boat
con -kinda noisy and not the smoothest engine made.

what i should lookout for and possible problems i may come across.

the blocks and manifolds are often cracked from neglect - not winterizing properly -get a bright flashlight, and crank your head upside down under the manifold and look for welds or sealant on the block and bottom surface of manifold

You have an OMC stringer drive- the engine should really be the least of your worries. That drive is a tough one to keep water sealed out of, and has some stupidly expensive parts, like a $600 shift cable and $1000 gear sets.

If you are redoing the stringers and transom, it sounds rough, you may want to part the boat out and junk it.
If it has sentimental value, you might want to change the drive system to Mercruiser while you rebuild the transom.
Committing to that drive system at this point would be regretted later.

 

[zbnutcase]

Re: Omc 1984 2.5

Yes I agree with Howard...the engine itself is the least of your problems...its the OMC drive thats the issue...

 

[shotblater1]

Re: Omc 1984 2.5

Thanks guys have taken you coments onboard. So its possible to change out omc drive to mercruiser drive but keep engine i have, Is that what you are saying.? Boat has no sentimental value to me other than it was cheap and that the hull is in great shape, O and i love working on older boats and give them a new lease of life. Have another working on also. Robalo 20 centre console. What speed wil the 2.5 push my 18.8 at roughly?

 

[ezmobee]

Re: Omc 1984 2.5

A Stringer drive is a totally different set up than a mercruiser. Totally different mounting and hole in the transom. Changing over to a Merc will require some fabrication.

I wouldn't expect more than 30MPH with that motor on almost a 19' boat.

 

[shotblater1]

Re: Omc 1984 2.5

fabrication to transom and motor or just transom? Thanks for your fast reply

 

[ezmobee]

Re: Omc 1984 2.5

Transom and motor mounts/stringers.

These are just hunks of fiberglassed wood so don't let it sound more complicated than it is. Just wanted you to know that the transom hole for a Stringer is much larger than that for a Merc

 

[shotblater1]

Re: Omc 1984 2.5

Thanks again, Just working out whats best to do before going to deep. fab bit doesnt worry me as much as the end result for my time and effort plus the exspense. Would like a few more horses but dont we all lol...

 

[Rinker85]

Re: Omc 1984 2.5

I have had my 1985 omc 2.5 L since 1992 and have not had major problems with the engine or the outdrive. I've replaced the impeller in the lower unit and repaired my manifold. I do need to replace the ball gears next seanson. Those are the only 3 big things I've had to fix in the past 19 yrs.

I thought the Stringers are more realiable than Cobra models. Didn't the 86 and newer Cobra models put OMC out of business?

 

[Bondo]

Re: Omc 1984 2.5

Just working out whats best to do before going to deep. fab bit doesnt worry me as much as the end result for my time and effort plus the exspense. Would like a few more horses but dont we all lol...
complete rebuild is in progress. stringers transom and deck to start off.

Ayuh,... You'll be Way farther ahead to part out this boat...
Lotsa folks are trying to milk some mileage outa that motor, 'n drive...
New parts are gettin' harder to come by,... The Used Parts market is Boomin',..
Cash in on it...

To do a Stringers/ Transom/ Deck, while keepin' the OMC motor/ drive,...
You end up with a boat to sell that Nobdy wants...
To do the same rebuild, 'n go to Merc. driveline,...
You've gotta find another rotted out boat to use as a donor boat for this barge...
No, you can't use this motor with a Merc drive...

Just don't make no sense...

 

[shotblater1]

Re: Omc 1984 2.5

Well from what i have heard scince starting this thread is good and bad over this engine and drive and i thank you all for your coments. If i decided to go with a different engine and drive for this boat what would you guys look for .I.e motor size and drive.. Think i will pull motor and drive and go on with rebuild but wont cut any hole for drive and leave stern deck up until i make the decision on drive and motor.

Thanks again for your coments and please keep them coming.......

 

[Bluestream]

Re: Omc 1984 2.5

Well Merc are the most popular drives. You could use a Cobra if you found a nice one at a good price. The cut out is the same for both so cut away.

I agree with the not wasting time or money on the Stringer drive. You would never be able to sell it, and it would only bring you tears. Technology has moved on since they had their hayday

 

[ezmobee]

Re: Omc 1984 2.5

A Merc 4.3V6 package would be ideal.