PDA

View Full Version : Water Pump Question???



Jbb
10-31-2002, 03:12 PM
A Question??
The new boat Im trying to buy is a 2000 Eliminator 25 Daytona with a Keith Eickert 800 HP Engine.Soon as I sell my boat this one is mine.
The current owner is having a problem which we need explained to us.
This boat has been eating up water pump impellors at a fast rate We have only had it here for a month or so and it has smoked the impellor 3 times It appears when the boat is pulled out of the water,all the water in the engine and drive drains out the drive inlets...Imco Etreme SC drive ....Is this normal ...If so the next time you start the boat is the water pump impellor dry?
Or is there a check valve or something keeping it wet?
The owner has other boats.. A 23 Cougar and a few Velocities and says none of them drain as much water upon retrival as this one.
The water pump is A KE unit also but uses a standard mercruiser impellor
Im thinking that the pump should not be starting up dry everytime ?
Thanks in advance for any input ...JBB

TCHB
10-31-2002, 08:23 PM
The pump should run dry for at least 10 seconds before the rubber vanes are damaged. It sounds like you have a problem with the suction side of the pump being plugged or restricted. Are you using the same size impeller or is it to large for the pump housing?

Jbb
10-31-2002, 08:30 PM
Standard Merc impeller in a Eickert Housing ...one thing ..the inlet hose is huge as is the pump inlet fitting perhaps too large?

230Stingray
11-01-2002, 05:55 AM
Check the inlet hose clamps and make sure they are really tight! This includes the one that is behind the engine where the hose goes through the transom assembly. I have seen these become loose and then the pump starts sucking air and they wipe impellers out in a hurry. Think of it as trying to suck through a straw with a small hole in it, you can't hardly get any liquid through it.
Kent

rrrr
11-01-2002, 07:31 AM
JETBOAT BRIAN:
Standard Merc impeller in a Eickert Housing ...one thing ..the inlet hose is huge as is the pump inlet fitting perhaps too large?You may be on to something with this. The pump has to lift a column of water to be primed. I won't bore you with the calculations, but a 1 3/4" inlet hose has to lift two times as much water as the 1 1/4" inlet hose on a standard Merc pump. The difference in weight is substantial, almost 5 pounds of water versus a little less than 2 1/2.
Again, doing a lot of calculations would prove it, but there isn't any reason to have a bigger hose. The pump output is a function of impeller size and RPM. If you double the inlet hose size, it isn't going to double the pump output.
I'm too lazy to figure out the heat output of your engine and the heat rejection capabilities of the pump with water at 80 degrees, but my guess is the standard inlet hose is more than adequate. A 1 3/4" hose will move 30 GPM at 5 feet per second fluid velocity, the 1 1/4" will move 18 GPM. The 5 FPS velocity is a reasonable number for that pump, and 18 GPM is a lot of water.
The other thing... like an upside down water jug on a cooler, the size of the hose can determine if the water drains out of the engine. If it's too big, the weight of the water in the hose overcomes the resistance to flow in the block and it pulls the water out.
This is one of the few times having a big hose may be a bad thing. :D :D

Laveyman
11-12-2002, 06:12 AM
Have you tried one of those trick, wazuu blue impellors? I can't recall the brand name, but they're supposed to be the shiznit!

DUCKY
11-12-2002, 09:15 AM
I think you have a crack in one of the hoses, either the big one inside the boat, or the smaller one between the drive and the gimble housing. Check them all!

Tinkerer
11-12-2002, 06:48 PM
rrrr--- the pump doesnt see weight of the water only feet of head ( the height that it has to lift the water) It will take longer to fill the larger hose but I also think that You have an air leak.

Chaddyshack
11-17-2002, 04:56 AM
Stab in the dark here.....make sure that the intake and discharge hoses are not switched around. I have one occasion seen them reversed and the pump would only draw water at an idle. As soon as you try and put some rpm to it, it cavitates the pump and smokes it.

mike37
11-17-2002, 08:18 AM
Check the water pump housing if you smoke an impeller it may have damaged the housing of left some residua that is keeping the pump from working properly
And also make sure you are installing it in the right rotation
I know your knot stupid but it happens good luck

DUCKY
11-20-2002, 12:33 PM
Another idea:
That huge inlet hose should be a hardwall unit. It should have spiral wire imbedded in it (Like exhaust hose) If it is not the right hose, or it has been damaged, the suction from the pump can collapse it.