Need help with impellor replacement

[John Lapic]

From the start, I'll let you know I am a novice at this so type slow and give me some help. I will soon tackle, based on your advice, an impellor replacement on my 1971 Johnson 9.5, model 9R71. I did buy a manual and want to make sure I do this right. I am actually planning to install a water pump kit since I am sure it has not been replaced for years, if ever.

According to the manual, after shifting to forward position, I remove 4 screws attaching the gearcase. Then drop the gearcase sufficiently to expose the shift rod connector. After removing the shift rod connector screw, the gearcase can be removed, exposing the water pump.

All this seems easy enough, but I have a couple questions.
1. Do I have to remove the gearcase extension, which the gearcase connects to?
2. Is there some type of seal or o-ring between the gearcase and the gearcase extension?
3. Is there anything I should be checking as I have the gearcase off and exposed?

This seems fairly straightforward, but everytime I tackle what I think is a 15 minute job, it takes me hours. I am expecting a fight to get the gearcase screws out. It has only been in fresh water, but over the years, corrosion can set in. I don't want to break off bolt heads.

Any and all advice will be appreciated.

 

[HighTrim]

Re: Need help with impellor replacement

Ill try to make it short and sweet.

1. NO
2. NO
3. Couple of things here. While the lower unit is down, I would check out the water intake area and screen and ensure that it is free of debris. Before re installing lower unit (lu), grease the splines of the drive shaft. I would also blow compressed air or spray the garden hose up the water line to free up any debris that may or may not be in there. I would pull the prop off as well incase the lu drops, to prevent damage. While that is off, clean off any old fishing line that may be wrapped around the shaft, and oil those splines as well with marine grease. Few things you will need, just in case you arent sure, is some gasket sealing compound and some oil. Oiling the fins of the new impeller will help it. You will also be surprised how easily the lu drops due to the weight of it. Good luck, and if you have any other questions there are a bunch of good guys on here.

 

[DJ]

Re: Need help with impellor replacement

Ill try to make it short and sweet.

1. NO
2. NO
3. Couple of things here. While the lower unit is down, I would check out the water intake area and screen and ensure that it is free of debris. Before re installing lower unit (lu), grease the splines of the drive shaft. I would also blow compressed air or spray the garden hose up the water line to free up any debris that may or may not be in there. I would pull the prop off as well incase the lu drops, to prevent damage. While that is off, clean off any old fishing line that may be wrapped around the shaft, and oil those splines as well with marine grease. Few things you will need, just in case you arent sure, is some gasket sealing compound and some oil. Oiling the fins of the new impeller will help it. You will also be surprised how easily the lu drops due to the weight of it. Good luck, and if you have any other questions there are a bunch of good guys on here.

Spot on advice by HighTrim, as usual.

 

[John Lapic]

Re: Need help with impellor replacement

Hightrim - thanks for the tips. The pic you have must have a story behind it, Looks like your boat dropped from the sky..................

 

[HighTrim]

Re: Need help with impellor replacement

Tks DJ, learned from the pros such as yourself.

I replied to your PM John. Pretty powerful boat to be able to nose dive in the water eh Actually it was sunk and is getting pulled out, you just cant see the cable due to the camera angle. WIsh it were mine, but sadly not. Mine is a couple years older lol

 

[John Lapic]

Re: Need help with impellor replacement

Hightrim tells me to get some gasket sealing compound. Is that for the gasket that came with my pump repair kit or for some other use? I told you I am a novice here......

 

[HighTrim]

Re: Need help with impellor replacement

Your manual probably calls for the impeller housing screws to be dipped in it, as well as to the bottom edge of the impeller plate. I may be wrong in this as I have not done a water pump in your model, so forget I said anything if this is the case. The manual will outline the steps for you. Another thing to keep in mind. Dont adjust the shift rod in any way while the lu is down. The length is important and tightening or loosening it will throw off its tolerances, causing you future problems. Also be careful when aligning the water line with the grommet on top of the impeller housing. If that grommet gets shoved into the impeller housing, it will cause water restriction issues after you have it all bolted up.

 

[John Lapic]

Re: Need help with impellor replacement

Hightrim - after reading more in my manual, it does talk about dipping screws in "Perfect Seal #4". I'll assume thats the sealing compound you are talking about. I couldn't see anything about sealing compound on the gasket however.

 

[John Lapic]

Re: Need help with impellor replacement

Is there no seal between the LU and the gearcase extension? Seems there should be a gasket or some type of seal between these to keep moisture out.

 

[HighTrim]

Re: Need help with impellor replacement

No, no seal there, and no sealant is reccomended. A little water leakage there is quite normal.

 

[samo_ott]

Re: Need help with impellor replacement

No seal is required there as there's water on the inside also coming out of the engine and out through the exhaust.

I always wondered about HT's avatar also. If it's being winched out, why does it looks like it's splashing into the water?

 

[jay_merrill]

Re: Need help with impellor replacement

I have never taken a 9.5 LU off but the description in the manual sounds like it is set up just like the 6hp. If so, the shift rod that comes out of the LU is joined to the shift rod coming down the mid section by a link that is about 3/4 of an inch tall, and has two hex headed screws in it. Each of the shift rods has a "detented" section close to the end so that, when the screws are fastened into the link, they lock the shift rods in place.

To take this apart, unbolt the LU while holding it. Let the LU gently fall until it stops because of the connected shift rod. You will have just enough room to insert a screwdriver, or socket on a 1/4 inch drive, between the LU and the midsection. Unscrew whichever screw (upper or lower) that you can get to, and remove completely so that the affected shift rod is released. Aside from a little friction from the water tube bushing, the LU should drop easily so, as HT said, hold on to it.

There will probably be a rubber o-ring on the top end of the drive shaft, just before the splines - remove this and save. You can then unscrew the water pump housing and remove it by pulling it up the drive shaft. Once you remove the impeller, you will see a small key on the driveshaft that is used to drive the impeller. It is removable and you will probably have to do so in order to get the stainless steel impeller base off. If you buy a complete water pump kit, there should be a new key included but save the old one just in case.

Follow the advice above, and any instructions in your manual, to replace your impeller. Don't foget to put the driveshaft key back in and don't forget the o-ring either. If this LU is like the 6hp, the only thing that I would disagree on is the need to keep the shift handle/upper shift rod stationary because, as long as you have the connecter properly in place with the screws positioned at the detents (this is not a great description but you will know what I am talking about when you see the rods), they can't be too long or too short. They are either in the right place or not, and you will know if you missed the detent because the first time you move the upper rod in an upward direction, the connection with the lower rod will be lost. In fact, I find that moving the upper rod down before mating the LU to the midsection, gives you a little more room to get a tool into the space, so that you can refasten the link.

Having a claw type "retrieving tool" is handy too because you can put the screw in it, inline with the shaft of the tool, to insert the screw through the space between the midsection and LU, before threading it into the link. I have found this to be extremely useful because it is very easy to drop the screw into the LU while trying to thread it with so little room to work. A screwdriver with retaining clips will do the same thing.

When you reinsert the LU, as was mentioned, be careful to get the water tube properly inserted into the pump housing grommet. You may find that a thin film of lube on the end of the water tube makes this easier. While doing this, you will have to kind of "finesse things to get the shift rods linked properly too. And, the splines of the driveshaft may fight you a little as far has getting the LU properly seated up against the midsection, after the link has been fastened. This usually happens because the splines aren't lined up with the slots in the bottom of the crankshaft. To overcome this, you can usually twist the LU a little while pushing gently upwards. As soon as the splines and slots line up, the driveshaft should slip into the bottom of the crankshaft and you will be ready to bolt the LU and the midsection together.

I have written a lot here to try to give you the info that you will need but don't worry about the difficulty of the task - it really isn't very hard. Good luck with it!