Tweet
Well, I finally started de-winterizing this weekend. Was out of town for the last two, so I was chomping at the bit to get going. And the weather cooperated beautifully.
At first, it was smooth sailing. Engine started up on the second try. Ran great. Replaced the pencil zinc in the HX and ran again to test for leaks. None!
Tons of raw water out the back (as usual). Idle temp between 150 & 160; in gear tied to the dock at 2000 rpm it came up to 180 and stayed there, rock solid as usual. I should have stopped there and left well enough alone.
Instead, I checked my engine log, and realized that it had been 4 years on the same impellers in both the raw water and antifreeze pumps! I hadn't changed them since I put in a Moyer rebuild and a brand new Moyer FWC in 2011.
So I got out my spares, which I purchased in 2012 and kept sealed in a Ziploc bag to protect them. Since I have a V-drive engine, the coolant pump on the accessory drive is easily accessible, and the thumbscrew back on the Moyer pump makes it a breeze to remove. The raw water pump, however, is another matter. It's a Moyer pedestal pump, mounted up high at the flywheel end, which is the farthest from the cabin in my V-drive configuration. Squirming into the opening, lying on top of the engine, I was just able to reach it. The thumbscrew back came off easily, but the impeller didn't want to come off. With a lot of coaxing (and cursing), a pair of needle-nose pliers, a sharp hook tool, and the loss of some skin, I was finally able to get it out, but not without damaging it. It was intact, with all the lobes, but was definitely tired looking, with creases showing at the base of the lobes. I replaced it with one of my new spares (from 2012), cleaned & re-greased the o-ring, and reinstalled the back.
Engine started right up, and I quickly checked for leaks on both pumps. None! Success? No, not quite. A glance over the stern showed a bare trickle of water coming out, with an occasional anemic "bloop". A far cry from what I had just an hour ago!
At idle, the temp quickly climbed to 180 and stayed there, with a tiny bit of steam in the exhaust. Increasing the rpm to 2000 caused the temp to start climbing above 180, with more steam. More water out, but still not near enough. Its clear I can't run this way without overheating. And the water's still pretty cold here.
So, what went wrong? Am I another victim of the "Impeller size mismatch" problem that was noted a while back? Or is the pump so worn that a new impeller won't seal properly, but an old, swollen one will? If so, I don't see how, as this was a brand new pedestal pump installed in 2011 with the impeller it was shipped with. I did note that there was a perceptable wear pattern on the backplate where the impeller had been rubbing it. Is this normal, or should it be perfectly flat? I do have a spare unused thumbscrew backplate, and could try installing that.
Unfortunately, I destroyed the old impeller getting it out, so there's no going back. I have two new impellers arriving from MMI tomorrow to replenish my spares.
Other deas? Suggestions?
At first, it was smooth sailing. Engine started up on the second try. Ran great. Replaced the pencil zinc in the HX and ran again to test for leaks. None!
Tons of raw water out the back (as usual). Idle temp between 150 & 160; in gear tied to the dock at 2000 rpm it came up to 180 and stayed there, rock solid as usual. I should have stopped there and left well enough alone.
Instead, I checked my engine log, and realized that it had been 4 years on the same impellers in both the raw water and antifreeze pumps! I hadn't changed them since I put in a Moyer rebuild and a brand new Moyer FWC in 2011.
So I got out my spares, which I purchased in 2012 and kept sealed in a Ziploc bag to protect them. Since I have a V-drive engine, the coolant pump on the accessory drive is easily accessible, and the thumbscrew back on the Moyer pump makes it a breeze to remove. The raw water pump, however, is another matter. It's a Moyer pedestal pump, mounted up high at the flywheel end, which is the farthest from the cabin in my V-drive configuration. Squirming into the opening, lying on top of the engine, I was just able to reach it. The thumbscrew back came off easily, but the impeller didn't want to come off. With a lot of coaxing (and cursing), a pair of needle-nose pliers, a sharp hook tool, and the loss of some skin, I was finally able to get it out, but not without damaging it. It was intact, with all the lobes, but was definitely tired looking, with creases showing at the base of the lobes. I replaced it with one of my new spares (from 2012), cleaned & re-greased the o-ring, and reinstalled the back.
Engine started right up, and I quickly checked for leaks on both pumps. None! Success? No, not quite. A glance over the stern showed a bare trickle of water coming out, with an occasional anemic "bloop". A far cry from what I had just an hour ago!
At idle, the temp quickly climbed to 180 and stayed there, with a tiny bit of steam in the exhaust. Increasing the rpm to 2000 caused the temp to start climbing above 180, with more steam. More water out, but still not near enough. Its clear I can't run this way without overheating. And the water's still pretty cold here.
So, what went wrong? Am I another victim of the "Impeller size mismatch" problem that was noted a while back? Or is the pump so worn that a new impeller won't seal properly, but an old, swollen one will? If so, I don't see how, as this was a brand new pedestal pump installed in 2011 with the impeller it was shipped with. I did note that there was a perceptable wear pattern on the backplate where the impeller had been rubbing it. Is this normal, or should it be perfectly flat? I do have a spare unused thumbscrew backplate, and could try installing that.
Unfortunately, I destroyed the old impeller getting it out, so there's no going back. I have two new impellers arriving from MMI tomorrow to replenish my spares.
Other deas? Suggestions?
Comment