OMC overheating,help save my vacation!!!

[sea wolf]

Re: OMC overheating,help save my vacation!!!

When you launch, you're not forcing water in either. If the stern drive pump is operating properly, it will prime itself & pump water thru the cooling system. I would launch it, & look to see if water is exiting thru the exhaust. If it is, you're all set. And watch your temp gauge. Good luck.

 

[Lodgepole]

Re: OMC overheating,help save my vacation!!!

The Cobra pump is near the top of the drive. That's why dunking the drive to the cavitation plate won't get the water high enough to prime the pump. Outboards and some stern drives have the pump mounted lower in the leg and will suck water from a shallower bucket.

 

[bruceb58]

Re: OMC overheating,help save my vacation!!!

The Cobra pump is near the top of the drive. That's why dunking the drive to the cavitation plate won't get the water high enough to prime the pump. Outboards and some stern drives have the pump mounted lower in the leg and will suck water from a shallower bucket.

I don't agree...Volvos and Merc Bravos have pumps driven off the engine(way higher) and they don't have a problem.

 

[Stinky_1]

Re: OMC overheating,help save my vacation!!!

I don't agree...Volvos and Merc Bravos have pumps driven off the engine(way higher) and they don't have a problem.

I was thinking the same thing. But, if those outdrives do not have extra breather/drainage holes, it would work just fine.

I am guessing there is some sort of check valve there, so once the pump has prime it sucks only from those intake filters. Otherwise when I was on plane the pump would lose it prime and cause problems. because its only in the water as far as the cav plate when your driving.

 

[bruceb58]

Re: OMC overheating,help save my vacation!!!

No check valves.

 

[Stinky_1]

Re: OMC overheating,help save my vacation!!!

it works!

it seems that it is very very important for the cobra OMC outdrive to have those other holes just ABOVE the cav plate in the water. if they are not submerged, your impeller will only suck air.

Now, I have other issues to sort out. but they are all non cooling related.

thank you all for your help. Hopefully others in the future will be able to learn something from this

 

[xltier]

Re: OMC overheating,help save my vacation!!!

yeah, I saw that.

I was always under the impression that running a boat in a bucket, barrel or otherwise was always prefered over using the muffs. I am starting to think I was missinformed.

I will be taking it to the lake tomorrow to try it out. hopefully once those holes are under the water too all my problems will go away. I feel like a fool, but probably have learned something.

here is to hoping it works. Ill post back when I have my results.

one reason for the muffs compared to the lake is that with the muffs the water is forced in by house pressure.it doesnt give u any sense of being able to suck up the water.seen boats that would run cool on muffs but not on the lake.muffs r fine doing maintenance but the real test is backing in the ramp and run it up on the trailer.go early before the crowd.

 

[fritzies5]

Re: OMC overheating,help save my vacation!!!

OP here...after several days of perfect operation we encountered the overheating again! The outdrive was partially raised while the boat was still in the water. Had maybe the top third above water. After lowering the drive back in (and starting) it overheated. Seems the impeller lost it's prime. Removing the intake at the T-stat housing and manually sucking in water it was all good again. Does anyone have an idea why after re-submerging the drive it won't prime on it's own? Is it possible that there is exhaust back pressure coming thru the t-stat housing and stopping the water flow? I ask that because whenever it loses the prime and we remove the intake hose there is exhaust blowing out the hose connection. It seems like once it's primed it overcomes this and water circulates as it should.

 

[fritzies5]

Re: OMC overheating,help save my vacation!!!

Anyone?

 

[sea wolf]

Re: OMC overheating,help save my vacation!!!

Are u sure the seal on the housing is seated? When you set the impeller in place, was the narrow end of the drive shaft pointing down? If u had to twist the housing cover to line up the bolt holes, u may have disturbed the seal. When u put the impeller in was the narrow end facing down to align with the shaft?