Sea water pump impeller vanes flipped to the wrong way . . . ???

[tpenfield]

Greetings,

An unusual issue . . . It appears that the impeller vanes in the sea water pump of my port side engine have (somehow) flipped themselves to the wrong direction.

All was good at the end of last season, but this year when I started the engines for the first time, I noticed the sea water pump of the port engine was not turning. The starboard engine is fine (new impellers last year).

I initially thought it was the belt had worn out, but upon further inspection the pump will turn the opposite way, but gives a lot of resistance to the point of not wanting to turn at all the correct way. Using my boroscope, I can see the impeller vanes and they are pointed the wrong direction. I am thinking maybe the engine rotation kicked backward when I shut it down last year ???

Anyway, other than taking the whole pump body apart, any ideas, tricks to get the blades to flip back? I did not want to force it . . . and I applied a good amount of force/torque to get the impeller to turn the proper way . . . it was a no-go.

Headed to town to buy a new impeller . . . just in case.

 

[dubs283]

I am thinking maybe the engine rotation kicked backward when I shut it down last year ???

Headed to town to buy a new impeller . . . just in case.

its possible that yes, the engine did rotate slightly opposite normal rotation upon shut down. this may have caused the pump/impeller to rotate opposite. in any case with the vanes flipped in the wrong direction and having sat for a while they most likely have a set and will not easily return to normal

you could remove the impeller and install it opposite from it's current position but if you are going that far it's best to replace it. i would recommend replacing both impellers so they are of even age/wear but it's your boat. do what you wish

 

[tpenfield]

Don't tell anybody, but was able to get the impeller vanes to flip back to their correct direction. I removed the output hose from the sea water pump and lubed up the internals with dish soap. Then I rotated the pulley/impeller a few times ( in the wrong direction) to get the internal surfaces all nice and slick.

Finally, I slowly rotated the pulley/impeller in the proper direction and the vanes all flipped back to their normal position.

I also checked the vanes with my borescope and they seem to be fine. I've run the engine for a while in preparation for an oil change. I do have 2 new impellers on-hand, just in case.

 

[Lou C]

Ted I was going to suggest that before I read what you typed lol. We are thinking alike!
Anyway here’s my new 1st start of the year procedure to avoid a dry start. Put on muffs turn on water. Fill up a couple of one liter bottles with water + Dawn dish soap mixed in. Disconnect hose from impeller housing to stat housing (or heat exchanger) fill hose with soapy water. Reconnect hose. Then start up. This lubes the impeller and the soapy water helps the vanes flip the right way...so they can’t start dry....

 

[alldodge]

Don't tell anybody, but was able to get the impeller vanes to flip back to their correct direction. I removed the output hose from the sea water pump and lubed up the internals with dish soap. Then I rotated the pulley/impeller a few times ( in the wrong direction) to get the internal surfaces all nice and slick.

Finally, I slowly rotated the pulley/impeller in the proper direction and the vanes all flipped back to their normal position.

I also checked the vanes with my borescope and they seem to be fine. I've run the engine for a while in preparation for an oil change. I do have 2 new impellers on-hand, just in case.

Figured that would work
Also surprised the motor was unable to fix it self

Good to know

 

[tpenfield]

The fact that the engine and belt would not turn the pump led me to realize that the v-belts were beyond their useful life. So, I spent the better part of last night and today sourcing new belts.

NAPA was closed, but AutoZone came to the rescue and got me the belts on short notice and a holiday...
I fixed the impeller, changed the belts and did an oil change.

the boat launches in 2 days.

 

[alldodge]

I'm might get the boat in the water next week. To many things going on, just no time, and its also been cold

 

[tpenfield]

BTW- the old v-belts were so bad that the alternator was only making about 12 volts when just one engine was running at idle . . . now it is up to 14 volts.

 

[tpenfield]

FYI -
I bought aftermarket/generic V-belts, and am posting the equivalent numbers for those who may be interested.

So I had to replace the sea water pump belt, the alternator belt, and the power steering belt.

The profile 'size' is known as a '15' section automotive (about 0.45" top width and 5/16" depth) . . . it is in between a 3L and 4L standard sizes

1) The sea water pump belt (Merc 57-69143Q) is 39.5", so the aftermarket belt number is '15395'. In a pinch a 15400 will also work as the idler wheel is adjustable.

2) The recirc. pump/alternator belt (Merc. 57-48122Q) is a 15470 or 15480

3) The power steering belt (Merc. 57-812427Q) is a 15560 or 15570.

Basically, the first 2 digits are the cross section (15) and the last 3 digits are the length (in tenths of an inch) . . . 395 = 39.5"

Generic belts are about 50% the cost of OEM belts and are pretty much the same thing.

 

[tpenfield]

The boat was launched for the season today . . . so far so good on the impeller vanes. Both engines held a nice 160˚F while underway today.

 

[Lou C]

Nice! I’ll be getting mine done next week...

 

[QBhoy]

Is this twin engine shaft driven by any chance ? Can you guess where I’m going with this, if she is twin shafts ? If not...ignore me.

 

[dubs283]

Is this twin engine shaft driven by any chance ?

iirc op has bravo sterndrives, both engines (if oem) are standard rotation

 

[tpenfield]

Crisis has been averted, . . . and yes, standard rotation, bravo drives, engine driven seawater pumps, etc. etc.

 

[QBhoy]

Excellent