fresh water intake problem -impeller already changed - Help!

[hack]

I put new impeller in starboard engine with that said I'm not getting any water to strainer or impeller,
took off first two water pipes off forward of impeller first an second cleaned reinstalled, still the same.
Is there another impeller forward of the one in back...?
Would a bad thermostat cause this , is there another water pump?
Does the impeller actually suck up the fresh water or is it vacuum or both? Seacock is open, took out grease sert
good flow of flow of water, 671 Detriot Deisal naturals in 43 dc
The sea strainer gaskets need replaced wouldn't think this would cause this big of an issue.
Any advise offered would be greatly appreciated - maybe can point me in the right direction.

Note: Had the heat exchangers flushed and cleaned 7 years ago to the tune of $3500!

[Photolomy]

Are you certain you put the impeller in with the blades the right direction? Your intake grate isn't blocked? The impellers have a pretty good suction (vacuum).

[piripucha]

Make sure the hose that conects the pump to the strainer is not sucking air. I am not familiar with the one in your engines, but on the 8V71 teh tube that connects the pump with the strainer is connical so if you put the hose clamps at the end of the hose it would ripple and let air in so the pump will not prime. It happened to me once. I hope this helps.

[rustybucket]

Sucking air is the normal issue. Even if you put the vanes in backwards they will quickly re-align the proper direction.

I'm guessing one of the hoses/fittings you took off is not sealed up good. For rubber hoses I like to heat them up nice and hot to soften them and then clamp the hose clamp down pretty hard on them. Old rubber hoses get hard and the hose clamp just doesn't have enough arse to clamp down on them.

Any pipes you took apart may need new gaskets and/or sealer.

Also, be sure to load the impeller up with soap or appropriate grease. If you put it in dry and have ran the engine you probably need to change the impeller. It takes about 10 secs of running dry to fry them.

[SEVEN]

I second everything that was listed above. I would also add that since you turned it over and ran it for who knows how long I would takeoff the impeller plate and re-verify that you have not broken a bunch of veins in the impeller. Check the gasket on the plate and verify that it is still in good working order. If the plate is loose you would be sucking air as well.

[hack]

thanks for all advice from everybody !

[SEVEN]

Let us know what you find.

[bigbill]

check the cam inside the pump, it may be deteriorated.

[sgharford]

Did you have any problems prior to replacing the impeller? If not, probably the impeller. I had hell of time figuring out it was bad impellers for my Onan generator. I completely rebuilt the pump and put up with all kinds of work arounds to prime before I found a seller on ebay who sold aftermarket impellers for the generator. Have not had a single problem since I put one of those in (there is a lengthy thread on this site regarding this). Note I had put 3 brand new (but old stock as not made in x years) OEM impellers in and ALL had the same problem. I think the rubber may shrink over time. You would never know by looking at them.

[Captain Ralph]

The sea strainer gaskets need replaced wouldn't think this would cause this big of an issue.

Yes it would..