Johnson 25 hp water pump

[cabezaverde]

Hello all,<br /><br />I am new here, so please be gentle. I have a 1998 25 HP 3 cylinder Johnson that I got pre season started today running on muffs. Do the muffs supply enough water to have it pumping out the pee hole ?<br /><br />I have read so many horror stories about overheating that I didn't dare to run the motoer more than 15 seconds or so without seeing a stream.<br /><br />Do I dare take her out on the water?

 

[rickdb1boat]

Re: Johnson 25 hp water pump

Welcome cabezaverde<br /><br />First thing to do is make sure the pee hole tube is clear. They have a way of clogging up over the winter. Run a piece of wire up the hole to clear it. If that don't do it, make sure you have enough water pressure to the muffs and you should see it peeing pretty quick. If not, you may want to investigate further. Was it spitting water out the relief holes on the lower unit up high??

 

[cabezaverde]

Re: Johnson 25 hp water pump

Put it in a barrel of water and it pees like a racehorse. Muffs just didin't do it I guess. Thanks for the help.

 

[Bob7]

Re: Johnson 25 hp water pump

I have the same problem with my Johnson 25 HP. The impeller isn't working and I can't find but (4) bolts and (1) top nut that holds it together. There is another bolt somewhere. I have removed the nuts to the shifting mechanism. I hate to beat no it too much as I don't want to ruin anything.

To answer your question. No I would not take your boat out onto the lake and start it. You had better make sure you replace the impeller first, the water mustg flow through the engine block to keep it cool!

Bob7

 

[Bob7]

Re: Johnson 25 hp water pump

Don't do it! You will burn your motor out!

Bob7

 

[HighTrim]

Re: Johnson 25 hp water pump

Don't do it! You will burn your motor out!

Bob7

If it is pumping fine in a barrel, it will pump fine on the water. Testing on muffs is not a true test that the water pump is functioning anyways, as the pressure from the hose by passes the impeller. Strange though that it would not work on muffs...I assume you had it over the water intake correctly and supplied plenty of pressure??

That being said, I always like to change the impeller on any new outboard to me for peace of mind, being that it is a critical component of the cooling system and its failure can be catastrophic.

 

[goodtimes]

Re: Johnson 25 hp water pump

It is very easy to pull the lower end and change/inspect the impeller. You don't want to loose an engine for $10.

 

[Bob7]

Re: Johnson 25 hp water pump

Chris,
This is interesting. Can you tell me more as I want to get the lower end disassembled to repair the problems in there. I am new to this sort of thing though am suppose to be some kind of a hot shot mechanic, but when it comes to boat motors it is a very different story. Problem: I placed the lower end into a plastic garbage can and started the motor. Water didn't pump through. I can blow air through from the top and get plenty of bubbles. I removed the four bolts, and nut along with the shifting mechcanism nuts. It will not come free, there has to be another bolt down inside somewhere? I don't like to be beating on it too hard as most components are made of aluminium. Thank you any information will be much appreciated.
Bob7

 

[woody66912]

Re: Johnson 25 hp water pump

these 25/30 hp do have relieve holes just below the anti ventilation plate .you can run on hose if you seal them off with tape.to remove l/u .remove water in take grates you will find the shift rod jam nuts split and remove plastic keeper.

 

[Bob7]

Re: Johnson 25 hp water pump

Hi Woody,
My Johnson is a 1989 25 hp. I do have a parts service manual for it. I have done all that the manual calls for but it still will not drop down. I can place two screwdrivers into it but the one end with the nut will not free up. I appreciate all this help and will try again soon but need to pick your brain for more in-put. Thanks.
Bob7

 

[HighTrim]

Re: Johnson 25 hp water pump

Click on the following link, then follow prompts to your particular model. Go to "gearcase" for an exploded view of all pertaining bolts.

http://12.2.215.22/pub/default.asp?...=EJ,ATV,SEADOO,SKIDOO,SPORTBOAT,LYNX,ROADSTER

Be sure that the tell tale line and nipple are free from obstructions, and that you have the lu sumberged deep enough for the water pump to function properly. You do have it completely submerged dont you?? Have you also tried it on muffs?

 

[woody66912]

Re: Johnson 25 hp water pump

bob7 if your refuring to the shift rod behind water in take greats slide jam nut down and remove plastic keeper.

 

[Bob7]

Re: Johnson 25 hp water pump

Hi High Trim,
May be I didn't have it deep enough? it covered the in-take filters, does it have to be higher? I tried it with a hose using muffs. Thanks! your in-put is appreciated. I will try it again deeper next time. If you can think of anything why the lower end won't drop down it sure would be great thanks again.
Bob

 

[HighTrim]

Re: Johnson 25 hp water pump

If you just had it at the filter, that is not deep enough. The entire pump needs to be submerged. Doenst explain why it wont pump on muffs though, as they bypass the impeller. You likely have a restriction somewhere.