How can tell when water pump needs rebuild?

[Assassin3F]

I replaced the impeller on my 3.0L Volvo sx gspefs. Now the machine isn't overheating but the engine doesn't appear to be sucking much water on the muffs.

I am concerned that the pump isn't sucking enough water...how much is enough or should be coming out of the engine?

 

[Scott Danforth]

Your hose is turned up full, correct? On muffs is different than in the water. You need enough water pressure to push water up to the height of the raw water pump. There are not self-priming pumps unless the boat is sitting in the water

 

[Thalasso]

The raw water pump is dependent on the static water line pressure/volume. On a hose there isn't enough pressure and volume compared to being in the water

 

[Assassin3F]

ose is cranked full and water is spraying out from under the muff. The hose has enough pressure to get to the pump but relativly little water is coming out of the drive.

 

[Scott Danforth]

How much water is coming out the idle relief ports? Very little will come out the exhaust

 

[Assassin3F]

I have pulled the drive cause I was getting a ticking noise from one of the ujoint bearings going to replace it this week. I will try and get a video once it is back on. I have great pressure on the hose but a lot more water is spraying around the muffs than is coming out of the engine. I never took it all the way to operating temp but the exhaust manifold was cool to the touch after 10 min at idle...just didnt seem like enough water was coming out. My concern is an airleak at the pump...but I have no idea how likely that is with these things. hoses look good though.

 

[jerryjerry05]

Don't know if the newer drives have a hole on the bottom like the older 275/280/290 drives did.
​There was a 1/2" hole that needed to be plugged on the bottom of the drive when using muffs.?????????

I use duct tape when using muffs on any Volvo.
The drive has to be dry or it won't stick.

 

[Assassin3F]

Jerry where in the lower unit would the hole be located? Are we talking beneath the skeg or would it be located in plain view on the side?

 

[Assassin3F]

ok...got it back together and running on the hose...damn pump starts spraying a small amount of water when the engine gets near operating temp. The water looks like it is spraying/drpping out from behind the pulley housing either that or it is coming from behind the camshaft directly above it. As the water gets worse there is an audible rubbing noise getting progressively louder. I want to replace the pump cause I dont think it is possible for the cam to leak water. There is no water in the oil and everything still looks kosher from that side...anything I am missing?

 

[jerryjerry05]

The hole would be right in front of the skeg.
​Sounds like the seals gone bad??
They have a link here to the Volvo parts.

 

[Assassin3F]

I think I just answered my own question but figured I would post it for any future reference. I do have a leaking water pump...but it isn't the raw water pump. There are two pumps on the engine as noted in the service manual and out here in the forums. The raw water pump which is expensive and goes bad from time to time and the circulation pump which is much cheaper and very occasionally goes bad.

Raw water can be rebuilt...circulation pump can not..besides I found a marine replacement for just under $60...

When the circulation pump or gasket goes bad water will leak from the gasket down the front of the block and spray off the raw water housing/pulley (on a 3.0 L VP; for all others it would be "when present on the crank").

When the circ. pumps internal seals start to go bad water will drip from the 'weep hole(s)' on the pump to indicate that the pump needs replacement...but they will drip right on down to the raw water housing as well and go spraying off the pulley, which is why I assumed it was my raw water pump leaking...it wasn't. Got a flashlight and got it up to operating temp, watched the water drip from the weep hole.

So my raw water pump is golden but my circulating pump is leaking from the weep hole. Gonna replace it after the weekend and I should be good to go for years to come.