Raw water pump

[rickasbury]

So, have been working through some issues with fuel...I think with all the cranking,or not getting water to the pump I fried the impeller. My 350 mpi is closed cooling. For water I have the merc foot and a thru hull- both hoses go to a strainer and then to the pump. I have it home on a trailer. When I got it running I jumped out of the boat to make sure water was flowing- it was not and the impeller came apart. It was a few years old.
My all brass pump had been scoured so I had sourced an after market impeller with two wear plates which seemed to work fine until the above happened. That company shut down so I could not buy the same set up. So, I ordered from merc and impeller with a wear plate for the pump side. I see another version of the pump the brass back plate that has a wear plate- mine is completely flat. So, to deal with the groves on that side I set up my belt sander and ground it back smooth. Maybe a 32nd or probably less of material. It went back together fine I think- plate sat up on the seal as I tourqued the two together. So once installed, still no water. I have lost the impeller before running on muffs before so I really try to avoid doing it...so I'm wondering how much of an air leak would cause the pump not to pull? The strainer had water in it, not full but it did cover the intake port inside the strainer. So while I had the thru hull closed, as far as I know, could it still be possibly leaking? Seal on the strainer? Would having the thru hull closed could that set up some sort of lock to where water won't come in? I'm really stumped! I think I will take it to the ramp and see if with everything in the water if it will prime and pull water, assuming I did not trash the impeller again. The temp gauge works off the coolant and not the raw water correct? So if it starts to run hot I can shut it down...any clues here? Anything else I can check? I pulled both ends off the heat exchanger and no impeller parts are in there..I do not have the cool fuel program...in the pump seemed to be most of the impeller.

 

[04fxdwgi25]

For missing impeller parts, the 1st parking spot for them is the power steering and oil coolers.

How was city water connected to the system when running on the hose, through the strainer or the drive leg? (having trouble following the run on description)

A very small air leak anywhere in the mix will cause loss of suction. Cheap flushing muffs can cause it, too.

I had that problem on a 7.4 B1 I had and found a hairline crack in the pump body.

The temp sensor does tell you the engine coolant temp. Problem with loss of raw water while the engine is still cool in a closed cooling system, the exhaust components that are made of rubber, and such, will severely overheat and be destroyed long before engine overheats.

 

[dubs283]

Is this a bravo or alpha drive?

Yes, an air leak will cause raw water supply issues.

Your other thread I posted to use a piece of sandpaper on a flat surface and move the pump back plate in a figure 8 motion to rid the grooves and smooth the surface. A belt sander most likely did not smooth properly, I wouldn't trust it. ymmv

If the setup is bravo drive I would put muffs on the drive water pickup, cover the low water pickup if equipped, close the through hull sea ****, open the strainer cover, remove the basket and place a hose directly into the strainer. Will require two hoses to complete.

Alpha drive is another story, oem closed cooled systems with alpha drive do not supply raw cooling water to the engine mounted water pump through the drive water pickup

Edit: apparently seacock needs to be one word.....

 

[Scott Danforth]

So, have been working through some issues with fuel...I think with all the cranking,or not getting water to the pump I fried the impeller. My 350 mpi is closed cooling. For water I have the merc foot and a thru hull- both hoses go to a strainer and then to the pump. I have it home on a trailer. When I got it running I jumped out of the boat to make sure water was flowing- it was not and the impeller came apart. It was a few years old.
My all brass pump had been scoured so I had sourced an after market impeller with two wear plates which seemed to work fine until the above happened. That company shut down so I could not buy the same set up. So, I ordered from merc and impeller with a wear plate for the pump side. I see another version of the pump the brass back plate that has a wear plate- mine is completely flat. So, to deal with the groves on that side I set up my belt sander and ground it back smooth. Maybe a 32nd or probably less of material. It went back together fine I think- plate sat up on the seal as I tourqued the two together. So once installed, still no water. I have lost the impeller before running on muffs before so I really try to avoid doing it...so I'm wondering how much of an air leak would cause the pump not to pull? The strainer had water in it, not full but it did cover the intake port inside the strainer. So while I had the thru hull closed, as far as I know, could it still be possibly leaking? Seal on the strainer? Would having the thru hull closed could that set up some sort of lock to where water won't come in? I'm really stumped! I think I will take it to the ramp and see if with everything in the water if it will prime and pull water, assuming I did not trash the impeller again. The temp gauge works off the coolant and not the raw water correct? So if it starts to run hot I can shut it down...any clues here? Anything else I can check? I pulled both ends off the heat exchanger and no impeller parts are in there..I do not have the cool fuel program...in the pump seemed to be most of the impeller.

if you have a bravo like you state in your sig, your impeller is belt driven from the front of the motor.

check for Bravoitis

 

[rickasbury]

if you have a bravo like you state in your sig, your impeller is belt driven from the front of the motor.

check for Bravoitis

I did a transom pull about 3 years ago, boat has sat for a couple of years after that on the trailer. All of those components were replaced, bit good suggestion!

 

[rickasbury]

Is this a bravo or alpha drive?

Yes, an air leak will cause raw water supply issues.

Your other thread I posted to use a piece of sandpaper on a flat surface and move the pump back plate in a figure 8 motion to rid the grooves and smooth the surface. A belt sander most likely did not smooth properly, I wouldn't trust it. ymmv

If the setup is bravo drive I would put muffs on the drive water pickup, cover the low water pickup if equipped, close the through hull sea ****, open the strainer cover, remove the basket and place a hose directly into the strainer. Will require two hoses to complete.

Alpha drive is another story, oem closed cooled systems with alpha drive do not supply raw cooling water to the engine mounted water pump through the drive water pickup

Edit: apparently seacock needs to be one word.....

I am a bravo 3 and I thought about putting a hose in it also...which is why I figured I would just put it in the water and monitor the temp...I have the strainer cover off, I can easily remove the pump supply hose and just put the hose in that hose which I think is ruffly what your suggesting...and when I did sand it, it was not super ruff but, if it still is not working I will pull it and redo...thanks for the input
..I like having the two water pickups...not sure why I do as other rinker owners regardless of boat size, don't seem to have this same set up.

 

[rickasbury]

For missing impeller parts, the 1st parking spot for them is the power steering and oil coolers.

How was city water connected to the system when running on the hose, through the strainer or the drive leg? (having trouble following the run on description)

A very small air leak anywhere in the mix will cause loss of suction. Cheap flushing muffs can cause it, too.

I had that problem on a 7.4 B1 I had and found a hairline crack in the pump body.

The temp sensor does tell you the engine coolant temp. Problem with loss of raw water while the engine is still cool in a closed cooling system, the exhaust components that are made of rubber, and such, will severely overheat and be destroyed long before engine overheats.

Thanks...I am running muffs...I will pull the pump feed line and put the hose in it...hopefully I did not toast the impeller! I started to pull the line off the power steering cooler..that thing being made of very soft brass and I was afraid to mess it up- so I decided to crank it and see before I chanced that. I don't believe I have a separate engine oil cooler...also, I assumed that the little bit of impeller missing would not clog it 100%- reduce flow but not clog it?

 

[rickasbury]

For missing impeller parts, the 1st parking spot for them is the power steering and oil coolers.

How was city water connected to the system when running on the hose, through the strainer or the drive leg? (having trouble following the run on description)

A very small air leak anywhere in the mix will cause loss of suction. Cheap flushing muffs can cause it, too.

I had that problem on a 7.4 B1 I had and found a hairline crack in the pump body.

The temp sensor does tell you the engine coolant temp. Problem with loss of raw water while the engine is still cool in a closed cooling system, the exhaust components that are made of rubber, and such, will severely overheat and be destroyed long before engine overheats.

Also, as I recall...I had to replace that power steering cooler but it seemed to have little restriction for flow through it.

 

[rickasbury]

Ok- pulled the hose, stuck the garden hose in, it fired right up and was pumping water no problem!
So I let it run...it ran for maybe 3 minutes and then sputtered and stalled. Guess I'm still having some fuel issues...I pulled the fuel water separator and dumped that out and either seeing still seeing some water or all the treatment stuff I put in it. It did the same thing the other day...after it sits a bit apparently it will restart.

 

[QBhoy]

Hi. I was working on a boat recently with similar issues. It was a searay with twin 5.7’s on shafts. Kept overheating and fried an impeller after winter storage.
Found that the sea water strainer lid wasn’t assembled properly. The wing nuts were cross threaded and giving the false impression that they were tight. Meaning that the lid of the strainer was drawing air.
Make sure absolutely all fittings and fixtures are tight on the suction side of the pump. Make sure it’s getting driven by the belt too. Not slipping. Possibly from being miss aligned.
You could prove the function of the pump itself by running a direct water supply garden hose down into the intake pipe of the pump. Between the strainer and the pump itself, perhaps you may have a cooler in line too. . That will tell you if you are drawing air or not.

 

[rickasbury]

Hi. I was working on a boat recently with similar issues. It was a searay with twin 5.7’s on shafts. Kept overheating and fried an impeller after winter storage.
Found that the sea water strainer lid wasn’t assembled properly. The wing nuts were cross threaded and giving the false impression that they were tight. Meaning that the lid of the strainer was drawing air.
Make sure absolutely all fittings and fixtures are tight on the suction side of the pump. Make sure it’s getting driven by the belt too. Not slipping. Possibly from being miss aligned.
You could prove the function of the pump itself by running a direct water supply garden hose down into the intake pipe of the pump. Between the strainer and the pump itself, perhaps you may have a cooler in line too. . That will tell you if you are drawing air or not.

Thanks- exactly what I did and the pump works fine, thx!