Volvo 3.0gs can’t get water pump to prime

[CapRedbeard]

Volvo 3.0gspefs

New boater here. Replaced impeller as an add on as I was doing some work on the power steering system. I had the water hoses disconnected and presumably drained some/most of the cooling system as I was working over the course of a few days. Now I can’t get the raw water pump to prime.

What I’ve done so far:
- new impeller (lubed), no water to thermostat
- old impeller (lubed), no water to thermostat
- disconnect inlet hose at thermostat and start engine, no water flow out of the water pump output hose
- press (hard) on muffs to try to force water into system, tried with engine off, on, and water pump disconnected. Water came through water pump hose when engine was off and hose was disconnected.
- flush system from power steering fluid cooler backwards to water intake, good
- flush system from water pump backwards through ps cooler to water intake, good
- flush system from raw water pump outlet through thermostat and engine to exhaust output, good

Im at a loss, any ideas?

 

[Scott Danforth]

Do you have the hoses plumbed correctly?

 

[CapRedbeard]

Do you have the hoses plumbed correctly?

I haven’t rearranged the hoses and the cooling system functioned properly before.

I should say that the power steering work I did was due to a seized ps pump that caused the serpentine belt to stop rotating. I was on the lake and I realized it relatively soon I believe (belt wasn’t even damaged) but the engine water got hot, about 175-180 tops. Towed in and it’s been in the garage since.

Regardless, water flowed freely throughout the system as described in my OP when I hooked the hose up to the different locations, so it seems to me there is no blockage.

 

[CapRedbeard]

Just realized I’m missing parts #5 and #3. Not sure if they fell out and got lost as I removed the impeller housing or what, but I’d imagine that is why I’m not getting a good seal and the pump isn’t functioning. That sound right to you guys?

 

[CapRedbeard]

I chatted with my local dealer and they are thinking that the water pump housing may be worn enough to cause there to be a lack of suction to prime the system. The back plate has noticeable wear on it even though the front of the housing feels smooth. Their recommendation is a new water pump for $475 because unfortunately I can’t purchase the back plate only without purchasing the whole pump. Their thought was that the pump functioned at a reduced level when it was already primed (before I took it apart) and now it won’t prime because the system is full of air.

Anyone have any experience with the pump housing wearing out to where the system won’t prime?

 

[bruceb58]

Are you in the water doing the tests or with flushing muffs?

Just so you know, in the water, the pump sits below the water line so the pump never needs to prime. Hopefully, you aren't testing this by putting the drive in a bucket.

 

[CapRedbeard]

Looks like the pump housing was indeed worn past the point of providing sufficient suction. I bit the bullet and bought the OEM replacement pump, installed it, and it sucked water perfectly on the muffs immediately when I started it up. The old housing was so worn out that the back plate with the bearing slid right off the shaft. I didn’t know that it was supposed to be pressed on until I bought the new pump. The guys at the shop were shocked that this old pump had been functioning at all when I showed it to them.

Attached photos of the worn out pump housing for reference if anyone else is having issues.

Problem resolved - thanks to everyone for your help!