Raw Water problem

[eseyoung]

When you did the change, did you remove the pump completely? As in take off the engine mounting bracket.

I actually put mine (pump) on upside down. I was in the process of running it out a bucket so when exhaust started bubbling into the bucket, i realized what a dumb thing i had done.

That said, it fit perfectly upside down. but not so much in the water pumping department.

 

[superdiver]

No, I only removed the cover.

 

[Peter B]

It has to be that thicker gasket, surely. Everything else checks out, or is unchanged. But a thicker gasket would allow a significant leakage past the end of the impeller, and prevent priming quite easily. Oh, one other thing, something my mechanic mentioned, as the strainer/seacock in my boat was recently replaced, much like you did...did you burp the strainer..? I used to have a horizontal one under the floor, now it's a fancy upright one, but when drained, you have to loosen the top clamping knobs and let water flow in up to the top. Just a thought. Has to be that or that thick gasket, in my view. The engine/pump should otherwise have no problem self-priming, and if the old impeller was intact, blockage should not be it either.

 

[rwidman]

I am considering adding a "T" to the supply hose to see if I can get it to prime that way...? what do you think that sounds like?

If you didn't have to prime it before you worked on it you shouldn't have to prime it after you worked on it. I've never heard of an engine raw water pump that had to be primed.

 

[superdiver]

It's a horizontal strainer. I tried to "burp" it but wasn't getting much of a result.

I never had to prime it before when I put it in or out.

 

[Capt.Bill11]

It's a horizontal strainer. I tried to "burp" it but wasn't getting much of a result.

Ding, Ding, Ding! You can't get much water out of the strainer? Is it below the water line? If so, sounds like you may have found your problem.

 

[superdiver]

Ding, Ding, Ding! You can't get much water out of the strainer? Is it below the water line? If so, sounds like you may have found your problem.

It is below the water line and fills up almost completely.. there is a little bubble of air opposite of the supply tip that goes to the pump.

When I rebuilt the strainer/valve unit, i used all the same pieces and only changed the gate valve for the ball valve... it is a little "taller" then the gate valve, but not more then an inch or so...

 

[FF]

Manybox store ball valves are pure crap, does water rush , not simply pass thru it when the strainer is opened at the far end?

 

[Pack Mule]

You said in another thread that you had the key drive type impeller like mine . Have you taken the cover off and made sure that impeller and shaft are keyed together ? I can see how it could be easy to push the key out of slot if it wasn't lined up perfect when pushing impeller on shaft . Just a thought .

 

[Shoalwaters]

What Fred said is right: take top off strainer, hold rag over open end and open the valve. There should be a storm of water gushing out.

You fitted a new impeller. Is it the correct one: is it tall enough? It should appear to be bulging out of the pump very slightly before you put the cover-plate back on. The bulge pushes against the plate and makes the seal.

 

[Irish Rambler]

The raw water pump fitted to a Perkins engine is normally a Jabsco. the pump should be self priming. As you've changed the valve I would start at the raw water strainer and check that water is in fact coming into it, if not the valve is faulty/blocked.
If you have water in the strainer simply disconnect each section in turn to trace the flow.
Before you start to work on it make sure your bilge pump is working.
You can now buy a 'run dry' impeller for Jabsco pumps, I have modified mine with a 'Speed seal' cover and screws which allows a quick inspection/impeller change needing only a pair of long nose angled pliers.

 

[Pack Mule]

Did you get your problem solved? We gotta know what the fix was .

 

[superdiver]

Headed to the boat as I type

Il will FOR SURE keep you all posted.

 

[superdiver]

Ok. So my BIL and partner in crime and I worked on Nimbus

Backing up.... I had the CAV unit on the over hearing engine rebuilt before I pulled the boat this spring. When I removed the CAV unit I shut the GATE valve off. It failed in the off position which we DIDNT KNOW UNTIL we restarted the engine and ran it for a while. Obviously it over heated.

We figured that out and rebuilt the thru hull system with ball valves as we had been planning on replacing those monkey gate valves.

Pulled Nimbus, did all the bottom paint, thru hulls, zincs and various other misc stuff.

Put Nimbus back in and tried out the engines. The strbd (over hearing engine of discussion) started right up. The port wouldn't start, but that's a different thread.

We ran the strbd engine until we noticed it was getting up to 180 REALLY QUICKLY and we shut her down.

And that's where this problem solving started.

Long story short, the failed gate valve caused a failed impeller. We replaced the failed impeller with a new one AND A THICK GASKET!

The thick gasket didn't allow the new impeller to work and caused the new impeller to fail.

I posted this thread and had TONS OF GREAT INPUT and tried again this afternoon.

We put in a NEW IMPELLER and we made a gasket out of a thin paper bag. We reassembled and disconnected a junction AFTER the impeller to see if it was working BEFORE the engine overheated.

Quickly the water was flowing and we shut the engine down and reconnected everything. We cast off and took it for a trial run. The Strbd engine heated up more quickly then the port as usual. We ran for about an hour and the strbd engine never got over 170.

We put the DONE stamp on that beotch !

 

[psneeld]

Go back and see what solutions were offered and when they were suggested in the troubleshooting process

As many people point out here....the first things to check are the simple things and the things not done/done differently that are often the culprit.

 

[Peter B]

Yes, quite a few of us felt if it wasn't a blocked intake or airlock in the strainer, then it had to be that thick new pump gasket...
Glad your quandary is finally solved. Now...happy sailing..!

 

[superdiver]

Yeah. I was thinking it was an air bible or the gasket or the impeller .

But I didn't think the impeller would go bad as easily as it did. We changed the impeller and gasket a couple of times but never at the SAME time which threw off resolving the problem.

All the advice on here lead me in the right direction. Thanks again !!

 

[Irish Rambler]

Really glad you got sorted, if I ever have to change an impeller I use washing-up liquid to lubricate it for first few minutes of start up (it helps with the fitting too).
Before replacing an impeller I always put a wet/dry vacuum nozzle up the water feed pipe in the direction of the heat exchanger to suck out any crud or little bits of broken impeller.
I hope someone finds these tips helpful.

 

[Pack Mule]

Just changed mine .It has 8 veins and 4 were broke . Found all 4 at the front of the oil cooler .

 

[Pack Mule]

I meant vanes not veins

 

[sunchaser]

I meant vanes not veins

My veins would be popping too if I found four broken vanes. Replacing impellers prior to breakage is not a sin and can in fact prevent ruined engines.

 

[Pack Mule]

My veins would be popping too if I found four broken vanes. Replacing impellers prior to breakage is not a sin and can in fact prevent ruined engines.

Yes your right and I know I was lucky . I was surprised when I found that four were broke . It was running around 185 and usually runs 175 to 180 . I made sure that all 4 matched up with the old impeller.

 

[Edelweiss]

Good for you!! I did the thicker gasket thing once too. . . . and more importantly only once!! Figuring out what is wrong and how to fix it correctly is a learning process and we can all learn by the experience of others or by trial and error!! Though the latter is the preferred method!!