Volvo Raw Water Impeller Not Priming

[Ultralite]

Volvo AQAD31A with DP 290. Recently changed raw water impeller and often cannot get it to prime while flushing on the muffs. Or I have it primed, and when I go to switch the hose attachment from rinse to soap for the Saltaway, I lose the prime. I've always stopped the motor immediately. I've checked the impeller and it is not damaged. I've taken the brass cover plate which had some wear and sanded that down which dropped the engine running temp by 10 degrees. Right now to get it primed I have to remove the cap on the raw water strainer above the impeller and then go back to the outdrive and hold the muffs firmly in place and plug the bottom pee hole. Engine has 2100 hours on it and this has never been a problem before and I've always changed the impeller myself every 100 hours. Engine temp is 185 when running at 3400 RPM cruise on the water.

So, what's the solution?

[JD5652]

Ultralite-

If the cover was aorn, then it is likely that the pump cam is also worn. The cam is located inside the pump housing. You'll have to remove th impeller once more. If it's a Jabsco pump, then the cam will either be on the top or bottom depending on how your pump is mounted.

[Ultralite]

Inside the pump housing there is a flat spot on one side which forces the impeller vanes to deflect. Is that what you're referring to as the pump cam?

[JD5652]

Ultralite-

Sorry for the late response.....yep that should be the cam.... it's usually made of brass or bronze and is normally replaceeble on most pumps. Do you know who is the actual OEM (Original Equipment Manufacturer) of your pump??....Sherwood??...Jabsco??

[Ultralite]

JD, how would I find out who the oem is on the pump? Last time I got it through Volvo, but would lover to avoid their ridiculously high prices.

I can get the pump to prime on the muffs if I remove the cover to the strainer. That tells me the pump is working. Most have pointed to an air leak somewhere on the suction side which is anywhere from the pump to the drive. Since it primes while in the water, some have pointed to a seal on the pick up tube in the drive itself. I will go through it this weekend.

[JD5652]

Ultralite-

Look on the housing for possible markings.....Jabsco typically has their name on the outside of the pump casing as part of the original casting.One other way is to call Volvo and give them the serial number of the engine....ask them the OEM and model number of the pump.

If you give me the exact full model number, serial number and year of the engine, I may be able to get the info on the pump.

[Ultralite]

Ultralite-

Look on the housing for possible markings.....Jabsco typically has their name on the outside of the pump casing as part of the original casting.One other way is to call Volvo and give them the serial number of the engine....ask them the OEM and model number of the pump.

If you give me the exact full model number, serial number and year of the engine, I may be able to get the info on the pump.

JD, from the tag plate on the engine:
AQAD31A 867967
# 2203110909

The cover plate to the pump has a #858469. No numbers on the housing.

I pulled the cover plate and took the following photos:







The leak damage on the bolts and clamp under the strainer housing was from a prior leak event on the original pump and has since been repaired. This pump has been on the engine for about 500 to 600 hours and several impeller changes. Prior pump was on the engine for 1400 hours. Did one seal and bearing replacement repair on it at about 1000 hours and it gave out completely at about 1400 hours, dumping water into the engine (caught immediately and flushed several times).

[Avenger]

From the look of the photos that cover plate is shot. If it's as worn as it looks, water will bypass from the pressure side of the vanes to the suction side which is probably no big deal if it's primed but enough to keep it from priming itself.

If you can't get a new one easily you could either try flipping it over if there's no writing stamped into the outside face, or get some emery paper (that's that 3M wet-dry sandpaper, it's usually grey) and a flat surface like the table of a drill press, or a piece of glass laid on a workbench and try to lap out some of the erosion.

[Ultralite]

I got a pm here instructing me to cover the pick up vents on the drived (I used duct tape) then fill the strainer with water. Did so and I found a slow leak from the seal behind the the impeller. So I pulled the pump and took it apart. The spring around the inner lip of that seal was broken and rusty and by the oblong inner shape of the seal, it was not sealing. The seal on the bearing side was fine as were the bearings. Looks like it's time for a rebuild kit. Also need to replace the bracket and screw under the strainer cup and will get a new cover plate among other things.

I think I've found the problem. Thanks for all the suggestions, help and patience.