kjberman

A friend was behind me, noted one of my motors was not spitting any water through the exhaust.....motor never over heated according to the gages. Then i was pulling it out, stuck my head back there and it was flowing water ......so i figured it was a weak impeller - switched it out, put it in the water - now it isnt even spitting water at all. We pulled it out - put it on a hose through the fresh water flush.....and it was fine (figured it would be). Put it back in the water - nothing. Just took the pump back off - impeller looks good......

Any thoughts????

Motors are 496 HO.....

outlawinil

I like to open the petcock by the water pump and let the air out before starting especially if you have drained the system by opening the water pump up. I think they can air lock sometimes

Boat Tech

have you had any work done to the drive or the transom assy at all? Sounds like air some place from the drive to the impeller. before you are starting the engine are you lowering the drive all the way down? Next time it is running with and with out water try to carefully put your hand on the impeller housing to see if it is getting hot or staying cool, some times it will get warmer if it is pumping air. check all the hose clamps you can find on the engine and also the one from the pump back to the transom assy to see if it is loose and they are installed all the way. Also the fresh water system could have a loose hose or clamp some place. If it is a bravo one make sure the four holes for the low water pick up at the front of the drive are clean. Good luck with it.

kjberman

I had both drives serviced this year - so yes they were removed. When its on the hose through the fresh water flushes, everything is good.......water comes out of the drive etc. I was thinking maybe its the pump itself - was going to switch the two pumps trying to elimiate a variable.

TWIN-SPINS

http://www.randrproducts.net/

hillbilly24

Have you had it out since the drive service or was this the first trip since then? If it is the first trip I would suspect you are sucking air somewhere, either the inlet hose got torn or more liekly the o-ring seal for the water passage from the drive to the bellhousing is not seated and got pinched or it is torn. If you have had it out since the drive service with no issues I would look at the raw water pump housing. They are a horrible design and the the back plate wears and causes the exact issue you have. They don't suck air but they bypass when this happens. If the grooves are much more then superficial it needs to be replaced or have a kit installed from one of a few companies out there that make stainless wear plates for them. A little modification is required on the mount bracket but they will save you thousands over the years in pump replacements. I don't know why they went away from the previous style pump with the disposable plastic housing, they came as a kit with the housing, the impeller, the front wear plate and all the required seals. They were faily inexpensive and trouble free. Depending on how old your boat is you may be able to get Merc to cover it under what they call customer relations even if you are out of warranty. I have seen them do this a few times for customers, they will only pay for the part though not labor at a shop and if you are doing the work yourself you may find it difficult to find a shop to fight for you because they are not getting enything on the deal immediatley. They will gain a customer in the long run but most folks don't see that end of it and will tell to pound sand.