1990 OMC Cobra 5.7

[79Rude115]

Just got a boat with a 1990 OMC Cobra 5.7, I think it is 260 HP but it does have the 4 barrel holley carb which I think was an option so it could be slightly higher HP.

I got it from a 1 owner and he has never had any problem with the boat other than routine maint

Can anyone please let me know if there are know common issues with this setup.

Also, what are the maintenance essentials to prevent problems?

 

[Don S]

Re: 1990 OMC Cobra 5.7

There are a couple of know issues.
OMC went out of buisness 10 year ago, still plenty of parts available thru aftermarket, OMC techs are getting fewer and farther between.
Ebay is about the only place to find OEM service manual (You really do need a set).
Maintenance essentials include yearly outdrive removal to check alignment, gimbal bearing lube, bellows replacement before they go bad, manifolds and riser inspections so you don't get water in your engine, just the basic I/O stuff.
Improper filling of the drive can cost you an outdrive, and removing the screw under the cobra decal on the drive is a big NO-NO.

 

[79Rude115]

Re: 1990 OMC Cobra 5.7

Many thanks. I will be looking to service the lower unit as soon as possible. I am sure there are instructions on that in the repair manual but i will probably have more questions when i tear into it. What all do i need to do to make sure the lower unit is tip top for the next couple of seasons?

How much can you save by doing your own lower unit service? I am very handy, and a little bit of a cheap skate, have rebuilt carbs on outboards, complete rebuilds on small engines and motorcycles. Am I better to pony up the cash and take it to an OMC professional or try to go it alone with the forums and the manual?

 

[danond]

Re: 1990 OMC Cobra 5.7

OMCs have twitchy shift cables. If they're adjusted properly, they work great. If not, they grenade your gearset. If you can't find a mechanic who knows this procedure (DO ASK), then read the manual and Stuart Hasting's website (Google for it) and do it yourself.

If your drive shifts properly and doesn't take on water, do the transom service kit (bellows, gimbal, etc) change the fluid (PER THE MANUAL - DON'T GUESS) and go boatin'.

Oh - never run without a water source, and don't run the engine with the drive tilted full up or you'll eat up your u-joints and other things.

That's about it. Otherwise, there's nothing really remarkable about OMC drives vs. Merc or Volvo (for the average boater) other than the original manufacturer being out of business.

 

[79Rude115]

Re: 1990 OMC Cobra 5.7

My factory manual is on the way. What tools do you use to pull the lower unit? Is it possible to get it on a floor jack? Is this a two man job? I saw some mention of some special alignment tool - is this required if so where do i get it?

Do you think I should do this myself or have it done? What would the cost for getting it done by an OMC mechanic be? Last, what kind of grease is best since I can't find any OMC grease?

 

[gcboat]

Re: 1990 OMC Cobra 5.7

First off here is the download for the Cobra drive - it is almost a must read:http://www.hastings.org/~stuart/cobra/
Two bodies are really suggested to remove the lower unit. It's bulky, has no center of gravity and if it falls and cracks, well -----.
The alignment tool is a must have - can't do the job without it. ebay a good source for that.
If you are handy with hand tools the job can be a DIY project. Just use your manual. By the way - you did buy an OEM manual ? No Clymer, no
Seloc ( the torn out pages are great for cleaning up spilled oil).
What type of "grease" are you referring to? For what application?

 

[79Rude115]

Re: 1990 OMC Cobra 5.7

OEM manual, was not cheap but I guess it will pay for itself in time

I am asking about grease for the U-Joints and the one fitting accesible without dropping the lower unit which I guess is for the steering. I was hunting a grease gun at walmart but they only had the el cheapo Wal-Mart brand grease which does not seem like the sensible route.

A little off the subject but I also need to know what to use in place of the OMC triple guard and where to find it.

I guess that since mine is a 1990 (built in 1989) it might have the old shift cable assembly but i don't know how it would have lived this long with it. I certainly can't operate my shifter with one finger so now I am nice a worried about getting it right!

 

[a70eliminator]

Re: 1990 OMC Cobra 5.7

That grease zerk is for your gimble bearing, OMC triple guard is available at most any marine store (good stuff use it) I can pull my drive myself in about 5 mins. well maybe a little longer it's a matter of removing 6 nuts, the drive isn't all that heavy.