impeller question

OK, here's an uber-noob question...

What is the impeller that needs to be serviced? Also, where is it? I'm guessing from what I'm reading that it has something to do with the outdrive, and probably sucks water in for engine cooling.

By the way, I know, in general, what an impeller is/does. I am a noobie to boats and just need to know if this is something I need to check/replace regularly, where it is, and how to get at it.

Thanks.

Re: impeller question

Here is the diagram for the upper gear case of the Cobra outdrive:




The impeller is #12. However, if you're not sure when the last time all the components of the raw water pump were serviced, it is best to just buy the kit and replace them all. The kit will include #'s 13, 50, 9, 12, 49, & 48. The water pump kit is fairly cheap, usually around $35-45.

To access the raw water pump, remove cover # 63, then the impeller housing bolts, and you should be able to figure out the rest. Be sure to lube the new impeller with gear lube before inserting it into the housing, and it will be a tight fit. Be sure to reseal both # 63 and the impeller housing with OMC Gasket Sealing compound, or Permatex Aviation sealant. You really need to get a manual to do it the proper way.

If you remove the impeller and find that the blades are gone, be sure to check your cooling system for the broken pieces - it can lead to overheating problems by clogging the flow of water. The thermostat housing is a good place to check for those blades, as they often get trapped there.

You should also invest in a factory OMC Manual for your engine/outdrive. It contains invaluable information about servicing your Cobra.

Also, take inventory of any replacement parts you may need for that 460 -especially manifolds & risers, because parts are almost non-existent and becoming harder to locate as time goes by. Ebay is a good place to look -there are sometimes guys that part those 460's out.

Re: impeller question

Wow! Thanks for the extensive answer. I found some more pictures and instructions in my factory service manual once I knew what to look for.

I winterized the boat yesterday but ran out of daylight to be able to check out the impeller. I'll have a look in the spring.