2.3L OMC Overheating and Shifting problems

[aolsen]

Well first off I bought this boat late last year with a few issues thinking it would be an easy fix well one thing lead to another, I rebuilt the carb, new plugs, plug wires, coil and points just as a preventative maint. thing and then when i took it out late last year it was overheating so i went home put a new outdrive water pump in it and checked the upper pump and put a new thermostat in it, ran it on the muffs and it was fine. Well i have been doing other things too it this year and i finally took it out today and it ran great we checked the timing it was right at 10 deg BTDC and the points are brand new, we motored around for pry a good 30 mins and the temp started to creap up on it. So i shut it off sat for a while to to enjoy the weather and we motored around for another 20 mins and the temp went to around 230 or so, and wouldn't come down. Could my of outdrive pump went out already? Could there be sediment in the block if so how do you get it out? Also it didn't want to shift into reverse in the lake it ground really slow like it wanted to fall in, but just wouldn't do it or it poped out once it was in, on the muffs it was fine. In FWD it would fall in just fine in the water and out on the muffs. Does it just need to be adjusted or is there bigger problems?

 

[studdy05]

Re: 2.3L OMC Overheating and Shifting problems

I would break that impeller back down and recheck it. Check also that the exhaust seal in the lower unit that the upper fits into is good, and that you have plenty of grease in it...the grease fitting is almost hidden.

The shifting issue tells you something is wrong in the lower unit most likely. Muffs dont give you the resistance that the water does turning the prop so you have to test it in the water...where the cable attaches to the lower unit could be off just a tad or the carrier bearing could have moved forward a touch...time to inspect that lower really good.

 

[aolsen]

Re: 2.3L OMC Overheating and Shifting problems

I pulled the water pump off of the lower unit and it was toast but i don't understand i put it on new last fall and it went bad the first time this year? Are the impellers suppose to be bent over on when it is in the pump housing or did they give me the wrong one at the dealer. Because it would seem that it would build up alot of heat rubbing on the cage houseing even when it is in the water at a higher RPM. Now when you check that seal and grease it does the outdrive need to be pulled off where the outdrive meets the pivot point (the six nuts on the outdrive) can you use any type of grease or is there a special spec?

 

[thannah84]

Re: 2.3L OMC Overheating and Shifting problems

aol....I am having the same problem you are...Overheating at high rpm's....How hard was it to replace the water pump? Dealer told me a wasn't a do it yourself kind of job unless you really know what you are doing.....I have changed out the temp sending unit and thermostat...Ripped the end cap of manifold off and exhaust elbow and all seems to be clear..Little rusty, but no blockages...

 

[danond]

Re: 2.3L OMC Overheating and Shifting problems

I'm assuming you have a Cobra-model drive made in the late 80's/early 90's. You didn't post that info, though so take this all with a grain of salt.

You need to get a factory service manual (no SELOC, not Clymers - find one on eBay) if you're going to keep these OMC drives. There's few people around anymore who know how to fix them and the manuals would be answering a ton of questions for you right now.

Regardless, yes, the impeller blades are supposed to be bent when installed. No, they don't build up heat when they have a water supply. If yours failed that quickly, I would bet $$ you ran the engine without a water supply. All it takes is a few seconds. Never, ever run the engine without a water supply. If that's not the case, start with the thermostat, then work your way to the recirculation pump. Pull all the engine water hoses off, flush the engine out as best you can.

Yes, it is definitely a DIY job. Very easy (assuming, again, that you have a manual as a guide).

Your shifting issue is not solved easily through these forums, you need a manual to guide you, and the issue is more likely the cable and the adjustment, not something inside the drive itself. Don't start by tearing it apart.

OMCs are very finicky with respect to adjustments. You can't guess (you'll be wrong) and if you're wrong, your gears go "boom". Google "stuart hastings cobra" and you'll find a site at the top of the listing with a TON of good Cobra shifting information as a place to start.

 

[aolsen]

Re: 2.3L OMC Overheating and Shifting problems

Yeah i have been looking around for a manual but i thinks its time to invest in one. I have been always pretty loyal on turning on the water and let it get a good flow before i start the motor but maybe i forgot once? I will pull all the hoses off and pugs out of the block and manifolds and do a really good flush and start there. As far as the shifting goes i think i will wait for a manual. Thanks for all the help and advise you have gave me. i have used this website since i have owned this boat and everyone here has been super helpfull thanks again everyone!!