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Johnson Evinrude Water Pump Impeller Change

In this video I replace the water pump and impeller on the 1994 Johnson 30HP outboard motor.

Johnson Evinrude Water Pump Impeller Change – Video Transcript

Hey there, Dangar Stu here, today's video is about installing a new water pump in a Johnson 30 horsepower outboard and is proudly sponsored by Marineengine.com.

This outboard is from 1994, in case you're wondering and I'm going to start by taking the gearbox off. This is actually some old footage for another video and then after that we'll get started with putting the pump on.

Next thing I do is take what's left of this intake grille off so we can get to the shift linkage inside here. There's a couple of Phillips heads, one on this side that goes through this one and into the other side and one on the other side down low, it holds the two grilles on. This is our shift linkage now that we need to undo using a couple of spanners. I'm just going to brush a little bit of this corrosion and some of these barnacles off it. Once you've got this collar undone you can lift it up and then undo this little section, here's a little sort of nylon wedge that stops it from coming off cause we need to drop this all the way off in order to let this rod here slide up through the gearbox.

So this is the little tapered keeper it splits along one edge so you can just open it up and take it off, once you got that little keeper off the collar will just slide off. Now we've got four bolts here, two each side and one up here. Since I took this gearbox off it's been painted and had a whole lot of other work done to it. Because it was painted the first thing I need to do is get a tap and just clean up the threads that the water pump bolts into. These are the threads, you can see they got paint in them, quite a lot in that case so I'm going to get the tap and clean them out.

Also it's worth mentioning while I'm here these seals I pushed in and I didn't have the Evinrude tool, the custom tool that sets the depth and it looks like they're in a bit too deep because think they should actually stop here. I've had a good look though with a torch and the bottom one doesn't seem to contact the roller bearing in any way so I'm not super worried but it'd just be interesting to see how they fare. Fortunately they're not hard to change down the track if we need to.

This is an imperial tap and die set being an American motor so there's a few ways you can go to find the right tap. This is the bolt that came through so obviously this is the thread in the diameter we want. With your tap and die thread you get a gauge like this so if you pop a gauge on like that you'll see very quickly whether the threads to course or to fine or whether it slots in with the bolt itself easily. Hopefully you can see there that gauge fits in nicely and that's 20 threads per inch. So now I need to measure the diameter of it, I can put these calipers on and it's saying 6 millimeter bolt if I convert that to inches it's .24 of an inch but of course bolts are all measured in fractions not decimal so we're no better off, all right let's google it. 1/4sounds about right so this is a quarter inch 20 threads per inch which i think is what this bolt is. I won't focus too much on tapping because chances are you don't need to do this if you were doing your water pump repair.

Always a good idea though if the threads are corroded and old it's always good to clean them out even if you haven't painted but the basic idea is wind it a little bit in and back it out. I was also taught to put a bit of grease onto the tap because as well as being a bit of lubricant the debris that you clean out when you're tapping it will get caught in the grease rather than just staying in the thread and you can pull it out, wipe the tap clean and you're good to go. These taps start tapered so don't really do any work until they're a fair way in. Then you're just taking some of the paint off backing it up to move the debris into the channel and then go a little bit further again and you can see all the gunk just comes out into the tap.

Alright the threads all cleaned out now so let's start putting the pump together. Once you've taken the old water pump off they say the next step is to clean all the old gasket material off, obviously we've done all that because we've actually painted this gearbox, but if you haven't then you just need to scrape it all off. Here's our old pump housing which is worth hanging on to for reference while you put the new one together. So we'll take this new pump housing out of this bag, now the first step it says here is to oil and install the shift rod bushing which is actually here, there's a bit of tape over here so I think it's actually pre-installed. It's in position you can see that's it there but it does fall out which is why they put the tape on.

The next step is to put an o ring into here that'll hold that bushing in. So the bushing's already in, we'll install the o ring. This is the o ring, quite a small but fat o ring and this is the o ring that seals around the shift linkage. They say to oil it rather than grease it so I'm just going to dip it in a bit of oil. I'll drop the bushing in some oil quickly, it's obviously the inside that needs oiling, they don't call for any sealant on the outside. So we'll push that in and then push this o ring in so you can see there now with the o ring in it can't fall out anymore. These pump housings are plastic and there's a stainless steel cup that goes inside that the impeller runs against.

That's the next thing, when you're installing the cup you'll see it's got these two tabs on the top there and they go into the two tabs here or the two recesses here so it should sit flush like that. If those tabs aren't locked in it's Going to sit proud. Next thing we're going to install is this funny shape seal, now it's easier to use BMCA adhesive in part number 318535 to hold it into the groove. I had to Google that and get some vague idea of what type it is and we'll find something else. All right a really quick search says that we can probably use this perfect seal, this kind of stuff, so that's what I'm going to do. Most of the time you see seals in grooves like this, o rings, it's normally just held in with a bit of grease because it's actually the pressure that holds it and it can't go anywhere but I'll use some of this perfect seal and see how it goes. All right, a bit of sealant in the groove and I'll just press the seal in all right. That's where we're at now. Oops, I missed a step, after you put that thick o ring in that goes around the shift rod there's a large o ring that goes inside the top of the pump housing. That goes above the metal cup that holds the impeller and so that goes in the center here.

Next step it says is to lightly coat the inside of the cup here with a bit of oil often I use grease but in this case they say oil so that's all do. After that we need to install the impeller by rotating it counterclockwise so just going to get it in, then with a bit of twisting motion as you're pushing so it ends up like that. It's the twisting motion that gets all the impeller blades pointing in the right direction. Next step in the process is to slide the drive shaft down through the pump but you can see here there's this sort of brass hex section and I believe that to be the inside of the original impeller, you can see here this impeller has a round brass section in the center and I think that's what this is so I'm just going to get a hammer and a punch and actually try and just drive this off the drive shaft. I'm expecting to see a flat section here which is how we key this simpler onto the drive shaft. I'm just going to grip it on this mid section that's a bit corroded anyway, it doesn't want any oil seals, any bearings, so it doesn't matter if it gets a little bit damaged. I'll actually try and heat this collar a bit and see if then we get it to expand.

Alright that's off, you can see the flat I was expecting to see where the key goes for the new impeller. I'll go put this on the wire wheel and just clean it up a little bit so there we go. That's the flat section that the impeller locks onto, it's showing its age this poor old outboard but then again aren't we all. Alright, just going to put a little bit of oil on it and then we're going to push it down through the pump, so the trick is that you push it through the pump housing until the flat section here has come beyond the impeller. Now what we've got is our flip section of the drive shaft here and then the section in the top of the impeller that has the flat section and we need to line those up so they're in the same position. This way this is the key that they call the drive pin I'm going to put a little dab of grease on the flat side of it to hold in place then we're going to stick that on the drive shaft like that.

Once we've got it on, realign it to the groove on the impeller. Now what we need to do is push the drive shaft and that key up into the impeller so it all locks together. The obvious thing that's going to happen is if I don't support it as I push the pump down it's just going to push the impeller key off. Then try and hold that in place and put a bit of force behind it with a screwdriver. Alright hopefully you can see they're starting to go in and then I just got to keep tapping this drive shaft up till it's locked in there. So now that key's kind of flush with the bottom of the impeller.

For the next step we're going back to the gearcase. Underneath the pump goes a metal plate, but between that metal plate and the gearcase goes a gasket. Before we put the gasket on though I'm just going to put some more of this gasket sealing compound onto the gearcase where the gasket goes. Before you stick it down it's worth knowing this gasket isn't quite symmetrical and indeed the plate so if you see there those two bolt holes line up if you flip it over they're slightly out so make sure you stick it down the right way. All right now, a little bit more gasket sealant on top of the gasket once you've got the top side of the gasket coated with sealant then just drop the plate on. I've got to be careful getting it on the right way. Although it's not symmetrical it's actually only slightly not symmetrical so it might look right one way but all the holes in the gearcase need to line up perfectly, if they don't just flip it over.

Then with a bit of oil on the splines and on the shaft just slide the drive shaft and the pump together down through the base plate through the oil seals and bearing until it's into the pinion. Next we're going to put in the six bolts and washers that hold it down. So a washer for each bolt. This kit came with a bit of sort of sealer, Loctite to put on the bolts themselves, but if you don't you can also put a little bit of this perfect seal onto the bolts, partly to hold them in and partly also has a little bit of anti-corrosion, particularly if you're running in salt water. Now I'm just going to lightly run all six bolts down until they're touching the pump housing, now the bolts are all the way down I'm just going to work around in a bit of a star pattern snugging them up like it would with wheel bolts for example, wheel nuts.

There isn't a torque spec in the instructions for this I could see but bear in mind you want it to seal but at the same time it is a plastic housing and it's going to crack if you do them up too tightly. So really what I'm after more than really cranking any of them is just an even pressure all the way around the pump housing so it's not distorted either. Here we've got a little water pipe grommet and you can see it's got these little bosses on the edge so we're going to push this down into the pipe outlet on the pump until those little bosses locate in the holes on the pump. So you can see there they just sit in and the loop sits on top like that.

The last two things that came in the water pump kit are two more rings this size and these go around the two ends of the drive shaft spacer. This actually only had one o ring at one end so it's good to replace those. Then I'm just going to put a little run of grease around both rings. That's pretty much it, putting the gear box back on is pretty much the reverse of taking it off so no real mystery there. I'm glad we went through this water pump though because it is a slightly different technique to the Honda's we looked at previously. So hopefully if you're looking to do this job this video helps you out.