Very sick '89 40 HP Johnson Tracker

I bought an old pontoon boat last winter. The guy claimed the motor ran great. I took his word for it. Towed it 200 miles up to my cottage and let it sit over the winter. This past spring I started in the driveway after replacing the lower end fluid (which was kind of milky) and after replacing the spark plugs. Seemed to do well in the driveway.

Took it to the launch and she wouldn't start. So I took it to the local marina (since tools and time are limited on my weekend visits to the cottage). They found the carberators needed to be rebuilt and adjusted. They also said the compression in the bottom cylinder was very low. The top was at 120 PSI and the bottom was at 80. They suggested a new head gasket. All that work was about $300. Put back in...ran great for about 8 gallons of gas.

This past weekend more problems arose. The motor was VERY, VERY hard to get started. To the point that the battery died on me from trying to get it started. Once started, she ran like a top. Getting her to start was an act of Congress. The choke position nor the throttle advance didn't make a difference on getting her to start. But, after each time, with enough finese, she finally started. But, it wouldn't idle. I had to keep the throttle advanced for it to idle.

Called the marina...they went to my dock and looked at it again to ensure their work didn't cause my hard start conditions. They inspected it and said they found aluminum fragments and dust on the bottom cylinder. The compression check showed only 70 PSI on the bottom and still 120 on the top. They said the motor's shot. That seems like a load of bull to me since it runs so well once it's started.

What do you guys think? Will a compression variance so great between the two cause a hard start? I was thinking about putting a new plug in that lower and just use up the rest of the life in the motor before a rebuild.

What's a fair price for a rebuild? And, are these old Johnson Tracker worth dumping money into? I was thinking about a newer 60 HP as a replacement...

Thoughts?

Re: Very sick '89 40 HP Johnson Tracker

well you have a 50 psi difference in compression. yes it would problems starting, and running it is only going to do more damage.

cost depends on what is wrong. could be just rings, could be badly scoured piston walls which would require a rebore. no matter it is a total teardown to repair it. at present is is worth as a hole motor imho $100.00, as it is a parts motor. if you take it apart, and sell the good stuff, you could probably come out at about $600 or so. lower unit good, good starter, carbs, electrical system, the motor is a good motor, i love the 40 &50 hp motors. when you go pricing a new or new motor, you may look really hard at rebuilding this one. this size motor is becoming very popular, in the tight gas market. on the toon if i were going to replace it, and the boat is rated for it. i would go with a 3 cylinder 70hp.

Re: Very sick '89 40 HP Johnson Tracker

Thank you for the quick reply, tashasdaddy.

Based on searching I've done here, it sounds like continuing to run it might not be the best thing to do. I'm not a wasteful person and this goes against how I've treated all the motors in my life, but I think I'm going to keep on running it and finish it off. The power trim doesn't work (seems to be a common problem based on what I've read here, too). The electric choke isn't so electric anymore (I have to flip the lever up and down under the engine cover), and overall it's pretty rough. Also, the motor seems to be underpowered for the boat - a 1974 Harris 28' pontoon. I'll probably just part this thing out when it's all said and done.

I can't find the USCG on the boat so I don't know what the limitations are for size. That's probably a topic for another thread. I do know I'll go with something used.

Are my chances pretty good of getting it to run better with simply replacing the plug in the bottom cylinder? It would be real nice if I could use the boat for the rest of the short MI boating season.

Re: Very sick '89 40 HP Johnson Tracker

TTT. Anyone have any idea if I can nurse this thing along with simply changing the plug in the cylinder with the low compression?

Also, since there's no USCG tag on the boat, what would be the biggest motor I could put on it? Do pontoons require the long shaft motor? (I'm assuming they do)

Re: Very sick '89 40 HP Johnson Tracker

in 1974 there were no requirement for boats over 20 ft. that why you don't have placard. Harris is still in business, contact them. changing the plug may help a little, but it is only going to get worse. the other thing you could do is pull the head and have a look, as long as you don't break a bolt, its a $35.00 gasket. you could have a blown gasket also. i think i would chance it and pull the head.

Re: Very sick '89 40 HP Johnson Tracker

The head was off only weeks ago when the dealership rebuilt the carbs and replaced the head gasket. I suppose the head gasket could be bad already, but I'm not thinking that's too likely.

The logic behind changing the plug was because I've been told is coated with aluminum dust from the cylinder wearing away. I was thinking a fresh plug would help it start better. When I have troubles starting it again, I'd change the plug again (if the cylinder hasn't given out completely by then).

Thanks for the tip about contacting Harris directly. I thought my USCG tag was just missing.

Re: Very sick '89 40 HP Johnson Tracker

You know, I don't know if you realize this, and I HOPE you either have towing insurance or really good friends there on your lake AND, you keep a fire extinguisher with you, right there, next to you if not connected to you in a holster at ALL times because when that motor finally does go, you could be looking at ALL kinds of issues .... do you even realize this??????

At first, I have been reading your replies and thinking to myself "is this post a joke????"

Even though the motor has low compression, "70 POUNDS PER SQUARE INCH" can still throw things, like SHARP shards of both aluminum and steel, let alone fiberglass from the motor cover in crazy directions and cause INSANELY severe harm to EVERYTHING within the radius of the motor. If the block splits, the 120 POUNDS PER SQUARE INCH pieces of sharp metal can travel further, faster.

And the pieces of metal aren't indiscriminate, if your motor blows at the dock, people at the dock around you and your motor are going to be inline for the flying parts as well. Do yourself a favor right now, get a lawyer on retainer just in case this happens, you can make a phone call and have legal defense ready.

If and when the motor blows, cuts the fuel line, the plugs are still firing and the fuel is still pumping, I hope you know how to abandon ship in a timely method because once the fire starts, and starts running through the fuel line back to the tank, its will be best noted here that you need to keep your head under the water until you hear the explosion. Then when you do come back up for air, pray the fuel isn't still burning on the surface of the water.

And of course lets not forget about 190+ degree water in the motor that will come spraying out when the block cracks as well. I hope you like 3rd degree burns. Actually, when the water starts spraying, it will probably make you move to abandon ship quicker.

This entire post of yours is like a prelude to the emails that come around for the "Darwin Awards" where people did something SO insanely stupid, even though they knew what the outcome would be!

Buy the new motor and install it on the boat. If you can't afford a new motor this year, call it a season and don't put others or yourself at such risk.

Re: Very sick '89 40 HP Johnson Tracker

Is it possible that this motor might just have a stuck ring and a good decarb might bring the compression up?

Re: Very sick '89 40 HP Johnson Tracker

ftltony - thank you for the negativity - it did nothing to contribute to my thread. This post is not a joke. My posts were well thought out and written. There's no need to get so elaborate and be hasty. I know there's a risk and I'm assuming that. This would be no different than a motor cutting loose in a car or truck. Even then, the extremes you illustrated are rare. I don't find this to be insanely stupid - especially not to the caliber of a Darwin award.


What's involved in doing a decarb?

Re: Very sick '89 40 HP Johnson Tracker

Re: Very sick '89 40 HP Johnson Tracker

Decarb, take a can of seafoam put 3/4 of it in the gas tank, with only 1 gallon of premixed gas. put the rest in a spray bottle. start the engine, and let it come up to temperature. then remove plugs, and them some real good shot of seafoam into the cylinders, replace plugs, let sit 15 minutes. restart, and spray the rest of the seafoam into the carbs, so the the motor almost stalls, wait and repeat until the seafoam is gone.then take for a wide open spin. then put in new plugs, ad premixed gas to the tank, and take it for a wide open throttle spin. it is going to smoke like a house on fire, during this process.

afterwards compression.recheck

i do believe the warning did go overboard, and the Darwin award statement was uncalled for.