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Need Some Advice Pleas....

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Fireman93

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I have a 1972 Johnson 100hp. Its my grandpas old boat he took good care of the motor. I was concerned though about it sitting for 4 years without being used. I am pretty sure he put stabilizer in it but not 100%. I recently drained out the old fuel and changed the LU oil puleed the spark plugs and looked at them they seem in good condition. I turned over the motor and it fired right up and seemed to idle pretty smoothly. I was just curious if there is anything I should worry about with it in terms of seals or anything like that from sitting for so long. I haven't ran it out on the lake yet just for a couple minutes in the driveway (with muffs on it of course). Any thoughts on whether or not I should be concerned with anything else on it would be greatly appreciated.
 
I would change the water pump impeller since it sat so many years and run a can os SeaFoam in the fuel tank. If it won't under a load in the water then you may need to remove and clean the carbs.
 
Yeah I thought about the impellar but seems to be working ok. Is there any easy way without tearing the LU apart to check that its working GOOD. I don't recall this model motor ever giving off a big amount of water from what I assume would be the discharge for the impellar. I have seen some videos of other people running the same motor or a close one to it and they all seem to be doing the same as mine. I do have some SeaFoam, I added some to the little bit of gas I put in when I did my test start. I do have a question about that as far running running the motor on muffs is there any concerns as far the amount of time I should run it or how hard to run it. I did notice the water was slightly warm after I had run it a couple times for a minute or so a piece. We don't have overwhelming water pressure on the hose either. Thanks for the response though I do appreciate it. I see you live in SW Ohio, I live around Dayton, though the boat is at Cumberland Lake in KY in a boat stall which it always has been.
 
Not sure why folks do not want to change impellers on a regular basis ( every 5 years or so ) ----They are made of rubber and only last so long.-----It is like playing Russian roulette with the motor !-----When a motor sits for many years it is tough on the impeller and it still ages.
 
Impellers must be changed when they are working OK, because the alternative is to wait till they fail. At that time you have about 2 minutes, at best, before your motor becomes a new boat anchor.

I am not familiar with your exact motor but the LU would need to be dropped to change out the impeller.

You shouldn't need a lot of water pressure to run on muffs, since the impeller should supply all the pressure you need. Depending on the motor, the water out the back can get fairly warm. The real test for a properly working cooling system is to let the motor warm up and see if you can put your hand on the cylinder head for more then 3 seconds. The head should be at around 145F and you should be able to touch that without burning yourself, but you will find it fairly uncomfortable. If you can't even touch it, it is way too hot, shut her down.

When in neutral, without a load on the motor, you should never over-rev the motor. If you do you can sometimes encounter a runaway motor. That is a motor that you cannot shut off. You can kill the ignition and disconnect the fuel but, what happens is the heat in the combustion chamber creates the ignition and the fuel in the carbs feed it and the motor continually increases RPM ... until it explodes. We call that a bad day. You really shouldn't do that.

Idling on muffs and a little throttle will not be a problem. You can probably do that all day, although the cylinders do carbon up a little when the motor is run without a load.
 
Thanks for the responses I appreciate the advice. I am not against changing the impeller at all I just wasn't sure of the "guidelines" for it. I am new to the whole thing of outboard motors so a little apprehensive about it but I want to do it right and take care of it for continued use into the future. My grandpa passed away and was dealing with illness for sometime which is why it has sat for 4 years. So its kind of a labor of love thing getting the boat fixed up and running again, so needless to say I will do what it takes and learn all I need to as I am doing it. I did find a old manual for the motor so hopefully can find what I need in terms of what I have to do to replace the impeller. I do appreciate any and all information on what it takes to change it out and anything else that you guys have to offer me. I will be making a trip down there within next week or so to do some minor repairs to the boat itself, was curious how long does the process take of changing a impeller out is it something that can be done relatively quick?
 
I do know that he did manage to change the distributor cap assembly and spark plug wires within past 5-6 years which from what I gather can be a huge undertaking so at least I got that working for me haha
 
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