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Outboard Motor Water Pump Impeller Replacement Guide

Outboard Motor Water Pump Impeller Replacement Guide – Video Transcript

The serial number on the engine we're going to be working on today is 0T147002. If we take a look at the application charts that we provide in the Sierra catalog we're going to be using Sierra part number 18-3319. This kit is going to contain every part we need to service the water pump on this particular outboard.

Now that we've located the serial number, we've got our proper part, we're going to talk about a few safety features prior of getting started. First thing we want to do is make sure that the lanyard, or the engine kill switch, is in the off position. If the boat is not equipped with a lanyard, to be sure that the engine won't fire while you're working on it, we suggest you remove the cowling and take the high tension leads off of all the spark plugs.

Now to get started what we're going to do is we're going to take and remove the propeller, that's going to require an 1-1/16" wrench, we're going to then drop the lower unit, take this in on the workbench and show you how and where the water pump is located. I'm just going to loosen the five bolts that hold the lower unit in place and then we'll get to a point where we can actually take a look and drop the unit.

Now that we've got the lower unit off of the outboard, we brought it in here on the workbench and put it in our lower unit clamp, you really don't have to have a lower unit clamp to work on this, this can be held in place on the vise, or with a vise, or you can actually just lay it on your workbench. But what we're going to do now is actually take the water pump housing off, using a 3/8 drive wrench with a 1/2 socket. OK, so once you have the housing loose, just lift up on it gently, remove this rubber thrust washer, slide the housing up and you'll see the impeller is gently tucked inside.

We're going to take a pair of pliers and we're going to gently pull this water pump out and inspect the, the cup and the impeller. This impeller actually looks like it's in fairly good shape for its age. We want to make sure that we don't mis-locate the key. Now we're going to pull the water pump base up and we're just going to gently lift that up. Now the water pump base is going to have your gaskets and your associated wear plates. We also do want a quick check to make sure we look at the seal underneath the base, now we're going to put a new base in on this application or this install.

Okay, we've located the new base plate that we need and the respected gaskets and wear plates, we're quickly going to assemble this, gasket goes on first on the base, then the wear plate, then the housing gasket on top of that. Now that we have this assembled we're going to gently slide this on the drive shaft and push it down into where its seats and aligns on the three studs and get it started into the cavity, the bearing cavity, that top bearing cavity.

Next we're going to install the impeller on the drive shaft. To do that we put the key in place in the slot on the drive shaft, take the impeller, slide it down the drive shaft and align the keyway on the impeller to the keyway on the shaft. Now we're going to install the housing, we're going to spray just a little bit of lubricant, just to lube that impeller until we get water on it. We're going to slip the housing over the drive shaft down onto the top of the impeller and line up, line the housing up with the three studs and gently turn the drive shaft clockwise and let that impeller fold into place while we push the housing down.

With the housing in place we install the washers and the nuts and we want to tighten them down to fifty inch pounds. Now that we got the housing back on and the proper torque applied to the bolts we want to put on this final little rubber thrust washer to seal the top of the housing and we're ready to put the unit back on the outboard.

Now that we've installed our water pump and housing, we're going to take the lower unit and put it back on the outboard. When you're doing this, particularly with large gear cases, it's wise to have a friend help you just because of the weight of the gear case. We're going to take the gear case and slide it back up into the lower unit of the motor. And we're home. Now that we have the unit back on the outboard motor, we'll just put the bolts back in, tighten it up and we'll be ready to go on the water.