Impeller issue on Alpha 1 Gen2?

[kanteen]

Hey all,
Got a 4.3L with Alpha 1 Gen2. Dewinterized and noticed the prop steaming on muffs. Normally, when it first fires up water will exit through the prop, then begin flowing out the idle relief. However, it seems like I only get a trickle through the idle relief now, sometimes nothing at all. Appears to make it to temp and not overheat, but i didn't really let it run long enough to know for sure. Impeller hasn't been replaced in many years. Would a bad impeller cause this behavior, or does this sound like an obstruction somewhere else in the cooling system? I plan to pull and inspect the lower outdrive, but looking for any suggestions before I begin. Thanks for any help!

 

[San_Diego_SeaRay]

Hey all,
Got a 4.3L with Alpha 1. Dewinterized and noticed the prop steaming on muffs. Normally, when it first fires up water will exit through the prop, then begin flowing out the idle relief. However, it seems like I only get a trickle through the idle relief now, sometimes nothing at all. Appears to make it to temp and not overheat, but i didn't really let it run long enough to know for sure. Impeller hasn't been replaced in many years. Would a bad impeller cause this behavior, or does this sound like an obstruction somewhere else in the cooling system? I plan to pull and inspect the lower outdrive, but looking for any suggestions before I begin. Thanks for any help!

The more experienced guys will chime in soon but I had a bad Bravo impeller and steam coming out the transom exhaust was the visible symptom. One quick method to start pinpointing your problem is to disconnect the raw water input hose at the t-stat housing and look for how much water output your impeller is providing. Be careful of the moving belts and start the engine with muffs on for ~15 seconds. Should be at least the volume of a normal house water hose would provide. If it's not at least that amt then I would start tracing back towards the impeller.

 

[QBhoy]

I’d be checking the water isn’t coming out somewhere in the engine bay, as a result of frost damage perhaps…or a loose fitting ?

 

[Rick Stephens]

Personally, I'd replace the impeller. Too much money under the hood to risk it.

 

[kanteen]

Personally, I'd replace the impeller. Too much money under the hood to risk it.

Thanks Rick. Would that cause the idle relief to not kick out any water?

 

[kanteen]

I’d be checking the water isn’t coming out somewhere in the engine bay, as a result of frost damage perhaps…or a loose fitting ?

Best I can tell the bilge is dry, but I will double check. thanks!

 

[flashback]

Thanks Rick. Would that cause the idle relief to not kick out any water?

Pieces of the old impeller would.

 

[Rick Stephens]

Thanks Rick. Would that cause the idle relief to not kick out any water?

A poor impeller and not enough water flow.

 

[nola mike]

Thanks Rick. Would that cause the idle relief to not kick out any water?

Yes

 

[kanteen]

Thanks everyone, that helps a bunch!