Impeller question(i'm stummped) maybe you know the answer?

[dubs283]

water should be present in the system as high as the surface of the lake water

therefore, yes, the pump mounted on the engine is below the waterline - it should have water in it, no need for it to "self-prime" with the boat in the water

take the pump apart and make sure the impeller is in good condition - with a new impeller, the pump should have enough suction to pull water into it and supply the t-stat housing with water

 

[tistore]

Impeller question(i'm stummped) maybe you know the answer?

I know there are tons of post on here about impellers...but here is one. I took the boat out a few weeks ago i have a 74 glastron with a volvo penta aq130c motor with a 270 stern drive.. the motor got hot fried the impeller so long story short got the boat home few weeks later which is today took the boat out again with the new impeller installed checked all the hoses made sure they weren't plugged. but what is happening is i start the boat up in the lake and still no water being pulled up from the impeller. i pulled the hose off right before the raw water pump which is a clear hose that i put on so i can see the water and sounds funny but i sucked on the hose and see water going through the hose so i know it's not clogged. i re attatched it to the raw water pump and start the boat and nothing it does not pull water to or through the pump....the raw water pump does have little scratches on the back wall of the pump...could this be the cause?

also at the inlet of the raw water pump if i take the hose and fill alittle water in the hose and blow on the end of the hose should i be able to blow water through the hose which would make the water go through the water pump with the engine not running or should it be a tight seal where i wouldn't be able todo that? does anyone know?

i'm just getting frustrated with this boat. my first boat and i haven't had a decent time yet on the lake.

any help would be appreciated thanks.........

 

[dubs283]

Re: Impeller question(i'm stummped) maybe you know the answer?

with the boat in the water, disconnect the output hose from the pump at the t-stat housing and run the engine

you should have a good, contant flow of water

if not, check for clogs in the hoses, otherwise, check the t-stat housing for impeller pieces - they will get jammed in there pretty good

if everything is clear, the scratches may be the culprit, some of the volvo pumps are pretty touchy in that area - may have to replace the whole pump assy

 

[tistore]

Re: Impeller question(i'm stummped) maybe you know the answer?

Yes all hoses and housing is clear of impeller pieces...i back flowed the system and water flows in and out easily...i just can't seem to get the raw water pump to pull water from the stern drive up the hose and into the raw water pump...i can disconnect it and suck water out of the hose right before the raw water pump but as soon as i attatch it to the raw water pump..the clear hose i have on there has no water in it. the hose that comes from the inlet of the raw water pump i followed it back to the back of the motor and un attatched it and put it in a bucket of water. it will slowly pull the water out of the bucket and once all the air is out of the system it works fine with strong suction...but once it has just alittle air in the system it stops sucking and won't pull water up again...can't figure it out.

if the raw water pump is empty of water right before you get to the lake should the raw water pump create enough suction to be able to pull water up and to the pump? i had the boat in the lake and i followed the hose that goes from the inlet of the raw water pump to the back of the motor and pulled that hose off and the pipe that it attatches to didn't have any water comming out of it. should water be pressurized by the lake to push water up and out of the pipe?

 

[Danny Mc]

Re: Impeller question(i'm stummped) maybe you know the answer?

You may have the hoses swapped on the RWP, easy to do if you're not careful.

 

[zbnutcase]

Re: Impeller question(i'm stummped) maybe you know the answer?

Sounds like a worn out pump housing to me...no one ever replaces 'em cuz they are so friggin expensive, and pumping ability slowly degrades until it gets to this point. The fact that you state once it gets a little air in it, it quits pumping-classic worn pump body symptom.

 

[tistore]

Re: Impeller question(i'm stummped) maybe you know the answer?

Yes they are expensive...is there a way around this? or a better solution? Or how would. Person find out for sure if the raw water pump is worn out? Is there some type of test a person could do?

 

[Craig W]

Re: Impeller question(i'm stummped) maybe you know the answer?

Might be a silly question for you, but could your impeller be oriented incorrectly inside the housing? It would then be running opposite direction and not sucking water....

 

[tistore]

Re: Impeller question(i'm stummped) maybe you know the answer?

ok thank you everyone for responding but i figured it out....the back of the raw water pump was dipped in kind of like a sink hole towards the center of the shaft...plus it had a few scratches on the back wall of the raw water pump so i figured the water was going around the impeller to the back side...sooo being cheap like i am plus watching american choppers i figured i would fabricate a piece to put in the raw water pump so it would fix it...sooo i found a thin pie pan or pizza pan and i cut it to the shape of the inside of the raw water pump plus drilled a hole so the shaft could fit through it and slid it in...ohh i hammered it flat and made sure there were no rough spots and then put the impeller back in...put the lid back on and walla...a cheap fix...not sure if it will last but i figured the metal tin is as strong as the brass so i will see how long it lasts...i'm thinking tomorrow i might run it for a few hours to see if it works for that long then pull the impelller out to see how much wear it might have on it or any at all...if it does work i saved about 120.00 dollars ....i will keep everyone posted on the wear and tear of the tin on the back of my raw water pump...hope it lasts...

 

[tistore]

Re: Impeller question(i'm stummped) maybe you know the answer?

ran for 2 hours and no wear on the tin i added to the raw water pump...i think it worked...we will see the next time i take out the boat.

 

[Bluestream]

Re: Impeller question(i'm stummped) maybe you know the answer?

Tistore, are you comcerned about rusting of the new metal part?

 

[tistore]

Re: Impeller question(i'm stummped) maybe you know the answer?

not really...this piece was outside forever and isn't rusting...maybe it's not tin...anyways i can use it the rest of this year and next summer i will replace it with the new impeller. i just figured it's cheaper then buying a new raw water pump.

 

[jerryjerry05]

Re: Impeller question(i'm stummped) maybe you know the answer?

THe rear seal might be bad.If it got hot you probably burned it.Put it together and take the pump off,try to blow thru it as you turn it.You should get NO or very little air.Take the pump off.Hook up a hose and put the pump in a bucket of water.
Try to blow thru it and see if there is air comming out and where there is air comming out.
The bottom of the pump: There is a screw,it hold the eccentric cam in place.
The cam might be worn down.They are available at any good Volvo shop.
Grooves in the back of the pump have to be real bad to make this pump not work.Post pics.J

 

[tistore]

Re: Impeller question(i'm stummped) maybe you know the answer?

ohh yes...it is rusting...well i have a basic idea of how to fix it...now i need a thin small piece of some type of metal (brass or copper) to cut the same shape out and install it on my raw water pump...but i will use this tin just for a few days just to get by and have some fun on the boat while the weather is decent. thanks for the info on the rusting issue....dang it...

 

[tistore]

Re: Impeller question(i'm stummped) maybe you know the answer?

ok fixed the rusting problem...i went and bought a little sheet of brass and cut the shape of the inside of my raw water pump..drilled the hole for the shaft and wa...la! fixed the rusting problem...the piece of tin that i ran for a few hours looked new still so i don't think there is a lot of wear on it...so until i have problems again guess i solved and saved me over 120 dollars...thanks everyone for the info.

 

[tistore]

Re: Impeller question(i'm stummped) maybe you know the answer?

Tistore, are you comcerned about rusting of the new metal part?

Thanks Bluestream...i fixed that problem by putting in a brass plate.