Maintaining a 20HP Johnson model 20BAL75B (1975)

[Joolz]

Hi folks, I'm two days into boat ownership and have absolutely no idea how to maintain the thing. Boat that came with a Johnson 20HP outboard didn't come with any manuals. I'm new to boating and have no idea how to maintain an engine, aside from a vague idea that the gear oil should be changed on occasion and grease should be squirted into it once in a while. I don't know which spark plugs to use, the mixture ratio or anything else. In other words I'm in desperate need of an owners manual or a service manual IMMEDIATELY. I've seen hard copies being sold online for a lot of money and would likely take a couple of weeks for one to arrive (I'm in Canada). Question is, does anyone have a source for a free PDF manual? Or at the very least a set of instructions on how to properly maintain an engine?

I'm so green that today I started the engine for the first time (in a large bucked of water) and I didn't even know where to find neutral. Yep, that's how pathetic a boat owner I am. Still I race motocross, there are 5 motorcycles in the family and 5 vehicles, am handy with most things (do most of the repairs myself) and yet the world of boating is a whole new chapter in my life. I truly could use guidance, preferably before I wreck something and come to regret it afterwards.

I have no idea if most outboards are similar to the one I have so any help/directions of where I can find info on how to maintain these are greatly appreciated.

 

[flyingscott]

the motor needs to run a 50-1 gas ratio. The gear shifter is on the left side when you are sitting in front of it middle is neutral. the lower unit uses 80w90 marine lube two slotted screws on the lower unit one upper one lower fill from the lower until it comes out the top. Is it pumping water

 

[Guest]

50:1 Ratio = 16 oz. of TCW-3 (2 stroke) Outboard Oil to 6 gallons of gas.

Buy this oil by the gallon, its cheaper than the separate 16 oz. bottles

You will need to carry propeller shear pins for that motor, these are intended to sacrifice themselves if your propeller hits a rock or hard underwater object.

This will also save your gearcase, but it will most likely ding up your prop, which is easier to repair

Always carry an extra set of spark plugs and a proper wrench to change them.

 

[F_R]

What you are looking for is an original factory Owner's Manual (not a service manual). An owners manual tells how to run and maintain it. A service manual tells how to fix it. It should be available here at iboats, but I can't find it listed. Give them a call. If all else fails, go to the publisher www.outboardbooks.com

 

[AEROCOOK]

Welcome.
I knew you were in Canada as soon as I saw that you had a mid 70s 20 hp, I had a 1976. These were not available in the USA which is why the BRP catalog doesn't list it. A canadian marina that still has old catalogs will be able to help you out with part numbers but the motor is essentially the same as a 25 hp that you will find listed in all online catalogs. That being said, my advice would be to buy a new water pump impeller. This should be always be done to any newly acquired outboard unless purchased from a reputable source who assures you that it was just done, even then, it doesn't hurt to take a look.
A failed impeller has disastrous effects and it's cheap easy maintenance.

 

[F_R]

Oh well that explains why I couldn't find the owners manual listed here at iboats. But they do list the 25hp. Just get that one. Same motor unless you get deep into the innards.

 

[Joolz]

my advice would be to buy a new water pump impeller. This should be always be done to any newly acquired outboard

Ahh, explains why all I can find is the 25HP when browsing American websites.
Did all the basic maintenance (as listed in another thread) but cannot figure where the impeller is or how to look at it/replace it. As you can tell I have not been able to locate an owners manual. Seeing how you're familiar with this (pretty decent) motor, can you please describe the process? All else in this motor is in top notch shape but as you said, it is cheap insurance to replace it if unsure.

I plan to take the boat to the lake for the first time on Sunday (2 sleeps from now) and now I think I ought to check the impeller before doing that. So if you or anyone else can please describe how I go about checking it on this Johnson 20HP, I'm all ears.

Exciting times. Got my boaters license this afternoon, working hard at the mods to the boat to get it ready in time for the first outing. So busy that I haven't had time to contemplate all the butterflies in my stomach (yet)

 

[hardwater fisherman]

There are some videos on youtube that might help.

 

[AEROCOOK]

There are some videos on youtube that might help.

This is good advice. Once the lower unit is off, the procedure for replacing the impellor is the same for all small outboards so even if you find a video of a different hp it will provide you with the info you need.

 

[Joolz]

Yep, saw a couple of utube videos on this, thanks for the idea. Far bigger job than I expected and not one I'm too crazy doing on my own, not at this time anyway. Hopefully my neighbour who is very versatile with Johnson engines can land a hand when I decide to tackle the job. For now though I'll just chance it, we've been itching to try out the boat. As stated earlier this motor is in superb shape despite its age, so hopefully this also applies to the impeller.
Btw while running it in a bucket of water it kicks up water nicely, to the point where it nearly emptied the large bucket of its water when I put it in gear and gave it a bit of gas - within a couple of seconds several gallons of water was gone. Is this a semi reliable way to tell that the impeller is indeed working properly?

Are there any other tests I could run tomorrow while at the lake to see if there's some sort of issue with the impeller? One obvious test is to see how hot the head is after it's been running for a while (seems that sand/crud in the impeller compartment will make it overheat) but are there some tests I could try to gauge the health of the impeller? Like how far water shoots or what have you? Remember, first time on a boat here, absolutely no idea of what to expect other than taking it very easy to start with. This is a custom made speed boat (15.5') with a steering wheel, so not sure if it will be as stable as your typical fishing boat with a deep V. Then again would a 20HP really be enough to turn a small boat like this on its side?

 

[Joolz]

For some reason pic of boat didn't upload. Trying again. Also note that the metal gas can in the pic has been replaced with a plastic one. And it now sits one foot towards the front of the boat.

 

[AEROCOOK]

It's been so long since I sold my 76 that I don't remember if it had a tell tale. FYI a tell tale is a water stream that pisses out under the powerhead, it's purpose is to tell you the water pump is working. Look for a good strong stream and since you don't know the condition of the pump, look at it frequently.

 

[Joolz]

Water indeed shoots out of a hole about halfway down the leg. Will take a video and will post it here in a couple of hours. If anything, having you folks look at it will give me a bit of peace of mind. Thanks for the help. Please check back in a couple.

 

[hardwater fisherman]

Look on tube for a video named Evinrude/Johnson 40hp plenty of water. That is what you should see coming from the exhaust relief port that you spoke of halfway down the leg. Just above the waterline when at idle on the water.

 

[lindy46]

New motor to you and you don't know its' history - I'd change out the impeller. It can work fine in tests, but if it's old, it could fall apart at any time. You don't want to overheat and be stranded on the lake.

 

[oldboat1]

^^agree. But only one big sleep before trying it out..... just keep an eye on it. (but then change out he impeller)

 

[Joolz]

Here, finally is the video. Took a lot longer than 2h to post this but it's been a very busy day, trying to get everything ready to go (which included adding two seats for driver/passenger and moving the bench to the rear, for the kids).
There seems to be a healthy stream coming from the hole. But as mentioned above, we have no idea how old this impeller is or how brittle the plastic is. So yeah, will definitely be keeping an eye out for it. I suppose if it stops spitting water it means the impeller is broken and I need to be towed back to shore huh?
Scary thing these impellers. So much relying on some plastic that may or may not give away at any time.
http://tinyurl.com/parp8jv

 

[AEROCOOK]

Water flow out the back looks good. FYI the impeller is made of rubber, with age they begin to develop cracks and can start to break apart, if one of the pieces becomes lodged in a water passage it can block the flow, this is why it's critical to know it's in good condition.

 

[Joolz]

Understood. And for my own peace of mind I'll definitely be checking its condition, hopefully sometime this week and definitely before we take the boat out again (assuming today's first run is a success and the boat is a keeper). Not having a manual I suppose I'll just watch plenty of utube videos and look online for further instructions on how to take it apart to inspect. Suppose I'd be looking for signs of aging? Such as tiny cracks or possible missing pieces? Would also be a good time to clean sand and other possible material from the area, especially if any is around the thermostat (based on a video I watched). If I find the impeller to be suspect, do I just replace the actual impeller or must I purchase some sort of kit that comes with other parts? A local Johnson distributor has good prices on these old motors and can get parts here the next day and they're located close to me. So I suppose I could just buy a new impeller and keep it as a spare anyhow. Seems like a good idea, seeing the consequences a bad impeller can cost.

 

[F_R]

People put far too much reliance on seeing them pee or shoot water out the exhaust. Just because it does that now, doesn't mean it will do that tomorrow--or this afternoon. The only reliable way of believing it is ok is to know you have a reasonably recent impeller in there. For some pictures of what happens to them from age, go to Ask-A-Member forum at www.aomci.org and look for the thread titled Picture of Running A Dry Impeller. They did get off-topic a bit, but pictures show how old impellers shed their vanes (yes even when wet). And it happens very suddenly.