OMC Cobra Impeller Housing Meltdown

[ImHoppy]

I have a 1990 Seaswirl Sable Cuddy with a 5.8L Cobra that I just recently bought. I was going to change the impeller and do other maintenance so I would know that everything was fresh before I get her out on the River. After I removed the cover over the water pump housing I saw the back end of the housing was melted and a piece of the plastic had actually separated from the rest of the housing. I removed the housing and needless to say the impeller was shot and little pieces of it were laying in the housing. I went ahead and cleaned everything out the best I could and replaced the impeller kit and housing. I've read that I should let it set 24 hours before starting so the gasket sealer can setup or something to that effect. I've attached some pictures to make sure that there isn't something else I should check or do before firing her up. Where does the water discharge from on the outdrive? I looked in the manual but can't find it. I want to know where to look to make sure it is pumping water before I let it run. I do have muffs and good water pressure and I know not to rev the engine or put it in gear with the muffs on...I just don't know where the water should discharge from. lol. Oh, the yellow looking stuff in the pictures is actually tan mud. My flash made it look yellow.

Thanks,
​Hoppy

 

[bruceb58]

You did buy a new impeller and a new housing right?

 

[ImHoppy]

You did buy a new impeller and a new housing right?

Yes sir. I had the kit with impeller, gaskets and plate and then when I saw the housing had melted down I was lucky enough to find the housing locally.

Hoppy

 

[Bondo]

I have a 1990 Seaswirl Sable Cuddy with a 5.8L Cobra that I just recently bought. I was going to change the impeller and do other maintenance so I would know that everything was fresh before I get her out on the River. After I removed the cover over the water pump housing I saw the back end of the housing was melted and a piece of the plastic had actually separated from the rest of the housing. I removed the housing and needless to say the impeller was shot and little pieces of it were laying in the housing. I went ahead and cleaned everything out the best I could and replaced the impeller kit and housing. I've read that I should let it set 24 hours before starting so the gasket sealer can setup or something to that effect. I've attached some pictures to make sure that there isn't something else I should check or do before firing her up. Where does the water discharge from on the outdrive? I looked in the manual but can't find it. I want to know where to look to make sure it is pumping water before I let it run. I do have muffs and good water pressure and I know not to rev the engine or put it in gear with the muffs on...I just don't know where the water should discharge from. lol. Oh, the yellow looking stuff in the pictures is actually tan mud. My flash made it look yellow.

Thanks,
​Hoppy

Ayuh,..... Welcome Aboard,.... I ain't an OMC guy, but,.....

Water goes from where the muffs meet the drive, up through to the impeller pump,...
From there out through a hose through the transom, to another hose, probably to the P/S Cooler, 'n then from there to the in-comin' port on the T-stat Housin',....

If ya got a P/S Cooler, ya might find some of the old impeller there, 'n it's a good place to back-flush from/ to with a garden hose,....

Eventually water is exhausted through the exhaust at the risers,....

 

[ImHoppy]

Thanks for the welcome Bondo.
I thought that a stream of water was discharged from the outdrive if the impeller was doing it's job? How does one know if the impeller is actually "working" when running the engine with muffs on? Or another way to put it is how can I tell if the impeller is actually doing it's job? Sorry I don't know how to word this to get my question across.

Hoppy

 

[bruceb58]

You almost have the boat in the water to tell for sure. Best way is to pull the hose at the thermostat housing and see how much water is coming out.

 

[ImHoppy]

You almost have the boat in the water to tell for sure. Best way is to pull the hose at the thermostat housing and see how much water is coming out.

So with the muffs hooked up and a good flow of water running to them I should start the engine and pull the hose to the thermostat housing and if I have a good flow of water at the hose I should be good, right?
I appreciate your help.

Hoppy

 

[bruceb58]

Well...it's a good start. Problem is, with the muffs, it could mask things so you also want to do it when you are in the water.

 

[ImHoppy]

OK. I'll check it with the muffs at home and then check it again once I have it in the water. I'm assuming as long as I have a decent flow of water both ways that all is well. Yes?

Hoppy

 

[Lou C]

As was noted you want to check the whole raw water line from the transom mount to and including the thermo housing for those parts of the impeller. In fact I'd remove the drive split the upper and lower and make sure the water intakes are clean and the water tube gaskets are in good shape.
With the boat in the water, the impeller hose at the thermo housing should put out a 2-3" head of water. Based on the looks of that drive I suspect marine growth in the water intakes..

 

[ImHoppy]

As was noted you want to check the whole raw water line from the transom mount to and including the thermo housing for those parts of the impeller. In fact I'd remove the drive split the upper and lower and make sure the water intakes are clean and the water tube gaskets are in good shape.
With the boat in the water, the impeller hose at the thermo housing should put out a 2-3" head of water. Based on the looks of that drive I suspect marine growth in the water intakes..

I should have known that with my luck it couldn't be something halfway simple...and inexpensive. Thanks for your input Lou C.

Hoppy

 

[Lou C]

No Title

Seeing as how the impeller was in that shape, pulling the drive is a good idea because you will find out if the driveshaft bellows was leaking, you can check the condition of the gimble bearing and u-joints. This is normal sterndrive maintenance. On the Cobra drives, there is a belllcrank in the pivot housing that can get deposits behind it, you want to clean those out and pack the area around it with grease. Use OMC gasket sealer on the gasket between the drive and the pivot housing. I rigged up a piece of all thread for the trim ram rod holes and some 1/2" bolts, to remove the upper from the lower to clean out the water intakes and replace the water tube gaskets. I put a scissors jack under the 2 bolts on the front of the drive and one under each side of the all thread. It will come right off that way. Otherwise it can be a real struggle.

 

[ImHoppy]

I have an appointment this coming Monday morning to have it checked out and serviced by a reputable company. I'll feel much better after someone who knows what they are doing checks it out.
Once again, thanks for everyone's help with this. It is much appreciated.

Hoppy

 

[Lou C]

Sounds like a good plan. Once these are gone through and set up properly they are quite reliable, at least in my experience over 12 years worth of salt water use.

 

[Lou C]

OK. I'll check it with the muffs at home and then check it again once I have it in the water. I'm assuming as long as I have a decent flow of water both ways that all is well. Yes?

Hoppy

Forgot to mention, if you try to check the water flow at the impeller hose where it connects to the thermo housing on the muffs, you won't see that much unless the muffs fit really tightly. That's not a true test. The best way is with the boat in the water. Keep in mind that the location of the impeller on the Cobra is in the upper gear housing, so the drive has to be submerged for the pump to prime. On the muffs you get enough flow to keep the impeller and the engine cool at or slightly above idle but that's it.

 

[ImHoppy]

Thanks for that Lou C. That's why I decided to take it to a repair shop. They have a Impeller Service for $149 plus parts.
It includes:Remove lower unit or pump, Flush water intakes, Clean water strainer, Install new impeller kit and Test run engine to confirm water flow. So for $149 plus parts I'll have peace of mind knowing it is done right. Sounds like a good deal to me. Hopefully they won't find anything major.

Hoppy

 

[jerryjerry05]

That little black hose is a relief hose.
It helps with the priming on initial startup.

I found duct tapping the muffs helps the flow to the pump.
That pump got that way from someone running without the water on or not enough flow from the hose.

 

[ImHoppy]

That little black hose is a relief hose.
It helps with the priming on initial startup.

I found duct tapping the muffs helps the flow to the pump.
That pump got that way from someone running without the water on or not enough flow from the hose.

Running it without the water on was my thoughts. The nipple that the little black hose attaches to was broken off at about the halfway point and was still in the hose when I took it off. Someone had put a plastic wire around the end of the hose to help it stay on the nub of a nipple that was left. A mechanic that was highly recommended by friends is going to come over tomorrow (Thursday) and check it over for me. I was going to take it into a shop but then I read some reviews of the shop that made me leery of taking my boat there. Hopefully I made the right choice (for a change).

Hoppy