Counter-rotating OMC 5.8L MPI

[nu_2_boating]

My first boat - a 27' Sea Ray sedan bridge, came with counter rotating OMC 5.8 liter fuel injected inboard engines. They were installed new in '95 and have 420 and 389 hours each.<br /><br />Don't have any books on them so I'm "fishing" for some info on maintenance, experiences with these engines or any input in general.

 

[nu_2_boating]

Re: Counter-rotating OMC 5.8L MPI

Someone that has/had the same engines?

 

[Captain Vis]

Re: Counter-rotating OMC 5.8L MPI

The 5.8 Litre is a great engine. The impeller should be changed each year ( it's on the engine) and you should change the oil every 100 hours. Other than those items.........enjoy ! Virtually bullet proof engines.

 

[CCrew]

Re: Counter-rotating OMC 5.8L MPI

Are you sure they BOTH counter-rotate? Usual twin setup is that one is, and one isnt.

 

[nu_2_boating]

Re: Counter-rotating OMC 5.8L MPI

Thanks for the advice, Capt. Vis. I found a repair manual on Ebay by Seloc thats specifically for the engines and outdrives, will be reading once I get it. <br /><br />CCrew - you are right, one screw spins on left hand, the other right hand. Is that done in the gears or the engines?

 

[Boatin Bob]

Re: Counter-rotating OMC 5.8L MPI

It's not real clear to me if these are I/O with Cobra drives? because in the first post you called them inboards which to me doesn't have a leg.But if they are I/O then normally the port side is the counter rotating and it's done within the drive not the engine.

 

[nu_2_boating]

Re: Counter-rotating OMC 5.8L MPI

Boatin Bob - I stand corrected, it has an inboard/outboard sterndrive propulsion system. OMC engines - I think they are Ford 351 and the stern drives are Cobra.

 

[nu_2_boating]

Re: Counter-rotating OMC 5.8L MPI

I was reading through the manifolds/risers section of the BoatUS catalog last night. It lists a chart of failure rates based on years of use. My units are about 8 years old and the chart says - they have a 90% chance of failure.<br /><br />How do you guys know when to change manifolds? Is it done as a preventive measure based on engine hours, or do most people wait for a failure then repair/replace?

 

[Boatin Bob]

Re: Counter-rotating OMC 5.8L MPI

A huge factor is where you do your boating, from everything I've read if in salt water 5 yrs seems to be about the norm. In fresh water it's a different story and usage plays a role in it as well. My OMC's are 460's, they are 1989 engines but in a 1990 boat and the manifolds/risers have never been changed plus they only have about 450 hrs.

 

[nu_2_boating]

Re: Counter-rotating OMC 5.8L MPI

My engines were installed new in '95. Hours on both engines are about 390 and 420. Boat was regularly used in saltwater but seems to have been trailered all her life - no bottom paint, minimal corrosion on outdrives. The engine components are starting to show signs of rust at edges of metal.<br /><br />Would it behoove me to pull the manifolds for an inspection, then make a call wether to replace them or not?<br /><br />I may be overdoing it a little but its my first boat and want my experiences on the water to be a good one.<br /><br />I'm even sending oil samples to Blackstone labs to see what's going on inside the engine.

 

[Boatin Bob]

Re: Counter-rotating OMC 5.8L MPI

Not sure if being trailered would matter unless prev owner flushed the system after every use. Once the salt is in there *&it happens. It's probably a good idea for you to remove them and see whats being going if nothing else then for peace of mind. Plus it could save you big $$$$ down the road or down the lake!

 

[nu_2_boating]

Re: Counter-rotating OMC 5.8L MPI

Yup, makes sense. I'm going to yank and inspect and replace if they look funky.