OMC Cobra 4.3 impeller disentegrating?? Cause & what to do?

[Robar]

I put a new impeller in as a precaution with the boat sitting for a year, and I had gotten sand in the cooling system. Started it up, was circulating water fine, idled to bring temp up, and it kept going up - shut off before got too hot. Impeller housing got very hot, so I knew what likely happened. The impeller just disentegrated - not melted.

This is the second time its happened, with the same brand impeller I bought at the same time. I used another with no problem in between. I noticed that the ones that came apart had a harder feel than the one that did not.

Anyone experience impellers doing this?

Now I need to take the hoses off and back flush everything - anything else to do?

 

[Gary H NC]

Re: OMC Cobra 4.3 impeller disentegrating?? Cause & what to do?

Sounds like you may be putting it in with the fins turned the wrong way.
Also did you replace the impeller plate?
Always take some gear oil or marine grease and coat the rubber when you put it in.
Also i would replace the round metal housing on the pump also..
I always buy mine thru Napa,which is a sierra made part..

 

[Robar]

Re: OMC Cobra 4.3 impeller disentegrating?? Cause & what to do?

Sounds like you may be putting it in with the fins turned the wrong way.
Also did you replace the impeller plate?
Always take some gear oil or marine grease and coat the rubber when you put it in.
Also i would replace the round metal housing on the pump also..
I always buy mine thru Napa,which is a sierra made part..

Thanks - I'm confident the fins were correct, and I lubed the impeller and surfaces with silicone lube. The fins should correct any rotational alignment as well with the flexibility.

The previous impeller that did not come apart was one I bought at Napa, and there was noticable differences in the rubber softness. The GLM ones are the ones that disintegrated. Everything seemed to be working fine, thats what confuses me.

The impeller plate and housing were new - a couple hours on them basically.

I'll replace it all again, and check for rubber pieces as best I can.

Somebody mentioned a critical place to check once, but I don't remember - any suggestions regarding flushing any broken pieces out?

 

[Gary H NC]

Re: OMC Cobra 4.3 impeller disentegrating?? Cause & what to do?

I would just flush everything the best you can,remove the big hose from the engine water pump and back flush it..
Feel inside the metal impeller housing..make sure it is smooth.
I put one on one time with the fins turned the wrong way and only about half of them turned themselves back the right way..it chewed it up pretty good.
You can flip the impeller plate over and use the other side if it is smooth..

 

[DHPMARINE]

Re: OMC Cobra 4.3 impeller disentegrating?? Cause & what to do?

Have you thought about using BRP parts ? I don't know why aftermarket is a problem,but if you use the real thing,maybe we can trouble shoot it better.

DHP