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353 Raw water pump replacement - boat in water?

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353 Raw water pump replacement - boat in water?

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Old 10-09-2016 | 10:20 AM
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Default 353 Raw water pump replacement - boat in water?

Got stuck in a shallow grassy - mucky area, likely destroyed both raw water pumps (over-heating). I have the water pickups on the nose cone, i think they are prone to plugging?

Anyway, was just outside our marine when this happened (depth finder didn't work) and was able to get back to the slip.

Never done a swap while in the water, any tricks or things to avoid?

Thx
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Old 10-09-2016 | 12:13 PM
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Being in the water won't change anything. I had my pick ups in the nose cone on my old 353 and I had the same issues since i boat in shallow water, I drilled the out drive for dual water pick ups and never had an issue after that.
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Old 10-09-2016 | 08:58 PM
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If you don't have water shut offs (mine does not) then you have to pull the boat. If you have water shut offs between the transom and the water pump then just close them and you are all set.
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Old 10-10-2016 | 07:26 AM
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You can likely change in the water. Just hold the stiff hose up high (above water line), so water doesn't rush in.

However, if you have trashed the impellers, then you'll need to flush out the cooler(s) - otherwise, you'll have low water pressure and possibly an overheating condition. Generally, most people just flush with water, which is not always effective. You'll need to get the impeller pieces out of the cooler(s) with a pick or wire by poking through the holes (in the cooler).

Good luck!
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Old 10-10-2016 | 07:46 AM
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I always try to "rebuild" the impellers from all the pieces to make sure all are accounting for. If any are missing then you need to back flush from the t-stat. Also, little trick I learned. McCormick seasoning bottle fits perfectly into the end to act as a plug for the inlet hose.
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Old 10-10-2016 | 08:29 AM
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Originally Posted by Splitdecision271
I always try to "rebuild" the impellers from all the pieces to make sure all are accounting for. If any are missing then you need to back flush from the t-stat. Also, little trick I learned. McCormick seasoning bottle fits perfectly into the end to act as a plug for the inlet hose.
Was able to get to them in the water. One was good, water coming from the transom hose. However, the other was trashed and no water coming from transom hose.

My 353 has the flush kit, was able to run both motors when everything was installed again (had the hose running on the one). Concerned that I am plugged at the drive and likely will motor back to the launch on the port motor only.

I'd love to know what the mod is on the second pickup location. If I recall, didn't Merc go away from the pickup in the nose cone after only a few years? My 2000 Bravo 3 had the traditional side pickups, but not sure if they are the same as the Bravo 1's in 2000?
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Old 10-12-2016 | 03:25 PM
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The impeller will last about 5 min. without water. maybe blow air out through the hose to clear your pick up.?
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Old 10-12-2016 | 06:33 PM
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If you're concerned with the drive being plugged, then back flush it from the seapump hose.
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Old 10-12-2016 | 06:59 PM
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If you shredded the teeth off the impeller you need to back flush the system. Particles can not make it past the oil cooler. Remove all the hoses from there and run a hose through them. Using the flush kit will not get the particles out because the impeller pieces are on the other side of it. Jeff Wurl
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Old 10-12-2016 | 08:07 PM
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Drives are back in working condition

Used the flush system to back-flush the drive, cleaned out the mud from the system.

Ran it for a hal hour out on the lake, both ran at 170F.

Back at the well I think i found the source of a different problem, oil buildup on the from of the Port motor.

Had cleaned everything, after a few WOT passes - temps checked out ok. But, found oil leaking from the dipstick handle.

Not something I'd expect at 340 hrs, 75 hrs after top end redone ( but reading that this is somewhat common on a 502?). looks like its been there for a long time, assuming blowby?

Anyone have this issue? Doesn't happen anytime but at WOT.
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