2005 Mercruiser 4.3L MPI with Closed Cooling System
Alpha 1 drive
Serial Number: 0W020795
Just bought boat, had survey, all good to go. My mistake, did not sea trial after long discussion with mechanic who had been working this boat for the last 4 years. Low hours, 190 Starboard, 185 Port. (Twin set up, one engine being difficult)
Both engines were run on the flush system with muffs attached. Both engines came up to temp and ran very well.
First launch of boat, both engines get hot using raw water and depending on the sea water pump to provide cooling water.
At dock, reattach garden hose to flush system and they run cool. Starboard engine, once removing the garden hose from flush, began to suck raw water. (Not primed?) Port engine, would not. I suspected impeller was bad.
Changed both impellers. Starboard looked "burnt" but was intact. (Now new). Port was in pieces, which was a good sign because that could explain my problem.
I get, hopefully, all of the pieces out of the pump and system. After calling Mercruiser support, I determine that the power steering cooler is simply a brass pipe, no screens, no oil cooler that I can see, fuel cooler has no screen, and the screen at the heat exchanger has no debris.
I had lubricated the impellers and added a bit of dish soap to the pump. Start engines on the hard with muffs and flush system, soapy water emerges and both engines come up to temperature as normal.
Go to water, Starboard picks up raw water immediately, Port will not. Checked strainers, clean. checked the raw water/flush system valve, not stuck closed from raw water.
Sounds like priming to me. Next step may be to take the boat back to the water, loosen the top of the strainer, open the 1/4 turn seacock from the thru hull, flood the strainer bowl and lines removing the air, and see if it will prime. Alternatively, do as before and try running the motor, in the water using flush system and turn off the flush once flow has started to see if it will pick up raw water.
Interesting side note. I took both pumps apart to change impellers. Starboard side had a backer plate between the two pump halves. Port did not. The schematic does not show the backer plate in the pump. (I'm thinking this is a Mercruiser fix for something?)
If I didn't get all the pieces of the damaged impeller and they are restricting flow, where would they be?
Any help or ideas would be helpful.
Tom
Alpha 1 drive
Serial Number: 0W020795
Just bought boat, had survey, all good to go. My mistake, did not sea trial after long discussion with mechanic who had been working this boat for the last 4 years. Low hours, 190 Starboard, 185 Port. (Twin set up, one engine being difficult)
Both engines were run on the flush system with muffs attached. Both engines came up to temp and ran very well.
First launch of boat, both engines get hot using raw water and depending on the sea water pump to provide cooling water.
At dock, reattach garden hose to flush system and they run cool. Starboard engine, once removing the garden hose from flush, began to suck raw water. (Not primed?) Port engine, would not. I suspected impeller was bad.
Changed both impellers. Starboard looked "burnt" but was intact. (Now new). Port was in pieces, which was a good sign because that could explain my problem.
I get, hopefully, all of the pieces out of the pump and system. After calling Mercruiser support, I determine that the power steering cooler is simply a brass pipe, no screens, no oil cooler that I can see, fuel cooler has no screen, and the screen at the heat exchanger has no debris.
I had lubricated the impellers and added a bit of dish soap to the pump. Start engines on the hard with muffs and flush system, soapy water emerges and both engines come up to temperature as normal.
Go to water, Starboard picks up raw water immediately, Port will not. Checked strainers, clean. checked the raw water/flush system valve, not stuck closed from raw water.
Sounds like priming to me. Next step may be to take the boat back to the water, loosen the top of the strainer, open the 1/4 turn seacock from the thru hull, flood the strainer bowl and lines removing the air, and see if it will prime. Alternatively, do as before and try running the motor, in the water using flush system and turn off the flush once flow has started to see if it will pick up raw water.
Interesting side note. I took both pumps apart to change impellers. Starboard side had a backer plate between the two pump halves. Port did not. The schematic does not show the backer plate in the pump. (I'm thinking this is a Mercruiser fix for something?)
If I didn't get all the pieces of the damaged impeller and they are restricting flow, where would they be?
Any help or ideas would be helpful.
Tom
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