Raw water pump

[bboldt]

I have a 5.7l mercruiser alpha 1 Gen 2 with a new style raw sea water pump. I worked great a month a go. Put it on the hose in the yard no water through the pump. Check all the hoses for clogs, found none. Replaced the impeller still no water. I even put the boat in the water thinking low water pressure at the house, still no water through the pump. However i did not replace the black housing that the impeller sits in. It does have some small gougeson the inside of the plastic but not major. Any help will be great.

 

[Don S]

Re: 5.7 new style raw water pump

Re: 5.7 new style raw water pump

However i did not replace the black housing that the impeller sits in.

There is no black housing for a Gen II water pump. Do you have a serial number for this drive? Doesn't sound like a Gen II from your discription, pictures would also help.

 

[cr2k]

Re: 5.7 new style raw water pump

Re: 5.7 new style raw water pump

Did you get the drive key back in? The one that drives the impeller off the vertical drive shaft.
Was the drive in freezing weather and stored up?

 

[bboldt]

Raw water pump

I confused some last night. I have a 5.7l mercruiser with a new style raw sea water pump located low on the starboard side of the motor. I worked great a month a go. Put it on the hose in the yard no water through the pump. Check all the hoses for clogs, found none. Replaced the impeller still no water, I even backed the boat into the river low water pressure/ volume at the house, still no water through the pump. However i did not replace the black housing that the impeller sits in. It does have some small gouges on the inside of the plastic but not major. Any help will be great.

 

[Bondo]

Re: Raw water pump

Ayuh,.... We're gonna need yer serial numbers,...

A 5.7l, Alpha Gen.II should have the raw water pump in the Drive,....

So,... What have you Really got,..??

 

[bboldt]

Re: Raw water pump

The motor is a 5.7l Mercruiser with a Sea water cooling system over a closed fresh water system. The sea water pump will not pump water to the engine.
Motor: seral number OL654116
Out Drive: seral number OL850536
thanks for the help

 

[Don S]

Re: Raw water pump

Did you replace the orings when you replaced the impeller? If you have any kind of an air leak with those pumps, it will not suck water. Since you have run this several times now with no water, I would bet you no longer have a useable impeller. Might want to remove it and check it out.

 

[bboldt]

Re: Raw water pump

i replace the one o ring in the housing. i am sure that i turned the vains in the right direction according to direction arrow on the housing. i have been told that if you put them in the wrong direction the motor will turn them in the right direction. Does the small gouges in the housing have anything to do with problem.

 

[Don S]

Re: Raw water pump

If you have tried several times to start it and it won't pump water, you need to recheck the impeller and housing. Those pumps do NOT like to be run dry, even for a short time.

Did you per chance have the hoses off the pump for any reason between the time it worked and when it wouldn't pump the first time? If you did, it's very easy to get the hoses on the wrong fitting, so make sure.

 

[bboldt]

Re: Raw water pump

No, i didn't take any hoses off the first time; i felt that the impeller just went bad so i replaced it..... Would it be best to replace the housing and impeller or just the impeller again? I am testing the pump by pulling off the first section of hose that leaves the top of the pump and goes to the powering steering cooler, to see if i get water at that point and obviously have no water.

 

[Don S]

Re: Raw water pump

Would it be best to replace the housing and impeller or just the impeller again?

Like I have mentioned twice already, take it apart and look at it. Guessing if it's ok is a real waste of time.

 

[tpenfield]

Re: Raw water pump

Every time I change the impeller on my sea water pump I am always afriad of hooking the hoses up backwards . . .

. . . just a thought. . . .

 

[Bondo]

Re: Raw water pump

I am testing the pump by pulling off the first section of hose that leaves the top of the pump and goes to the powering steering cooler, to see if i get water at that point and obviously have no water.

Ayuh,... If I'm not mistaken,...
The water goes from the drive, through the P/S cooler, to the raw water pump...
So,...
That quote is Backwards...

 

[bboldt]

Re: Raw water pump

To Bond-o
This boat has what i beleave to have two pick ups one on the foot of the outdrive and one on the bottom of the boat that supplies the raw water pump through a high speed pick up... I also dont where the water goes once it enters the foot of the out drive there is no hoses that are conected to the engine.

 

[Don S]

Re: Raw water pump

Normally, the hose from the drive to the transom shield is cut off and the port inside the boat is plugged. This allows the pump in the drive to circulate water through the drive for cooling. There shouldn't be two ways of getting water at the same time. If there is, no wonder you have problems, and surprised it survived this long.

 

[Fishermark]

Re: Raw water pump

Just to add to all the above, I had the same setup in my boat a couple of years ago - I once replaced the impeller with a genuine Mercruiser impeller and it stopped working shortly after installation. It turned out to be a bad impeller. The rubber part spun free from the metal center. Kinda like a prop slip. Don't know how common that is... but it is something to check.

 

[Fishermark]

Re: Raw water pump

Here's the post I refer to above with more pertinent info: Impeller failure