1971 Sears 5hp Exhaust mod

[Chrisravosa36]

I want to mod the exhaust on this outboard. Its a water cooled exhaust engine, I wanted to mod the exhaust of come straight out instead of going down into the water. These engines I belive were built from lawnmower engines, so they are simular, they just have to push the exhaust down into the lower unit. I am planing on cutting a whole in the bottom plate were the exhaust comes out. Because I imagine if i get a new impeller, it will be fouled quickly. Im not running it on a bug body of water, just a small river that runs by my house, im not concerned about the gases. I just wanted to ask if this is a good idea?

 

[lmuss53]

I wouldn't do the mod, the exhaust gas is not that important, but you need the impellor working to throw some water up against the bottom of the block to cool that. That motor looks like a lawn mower engine but it's a 2 stroke, and that splash of water on the outside of the block keeps it alive. With the exhaust not going through the lower leg the little pump might not get the water up to the motor. I think the exhaust noise would be a PITA also, I run a newer but I'm sure similar version of this motor as a kicker I sure don't want it any louder.

 

[GA_Boater]

Why would the impeller be fouled quickly? The impeller is submerged in water and untouched by exhaust gases.

I would leave it alone. After after all, it's worked fine for 44 years and the engineers knew what they were doing even way back when. Cutting a hole will upset the 2 stroke back pressure, which is needed for proper running.

The noise will drive you batty.

 

[jbcurt00]

If it really is a lawn mower motor, why would you WANT it to sound even more like a mower then it does now w the exhaust softened by exiting underwater?

Some motors depend on X anount of backpressure. Changing the exhaust route, esp dumping to open air, has to change the backpressure.....

What made you ask this question?

 

[Chrisravosa36]

Because the water impeller is bad, the the tube snapped that hooks it up to the engine. How long could It run without water cooling it?

Why would the impeller be fouled quickly? The impeller is submerged in water and untouched by exhaust gases.

.

Were I am going to be using it there are alot of logs submerged, and the motor could get caught, this would make me think it will fail.

 

[F_R]

It's actually more closely related to a chainsaw. If you want it to sound like a chainsaw, go ahead and open up the exhaust. You must not have any neighbors or others on the water because they would either call the cops or shoot you. A better option would be to figure out a way to put an above water muffler on it. Even then it would make enough noise to wake the dead.

 

[GA_Boater]

Logs won't make the impeller fail. What model Gamefisher ?

 

[Chrisravosa36]

1971 5hp Gamefisher, the problem is that it kits the log, and the motor comes out of the water, and could possibly get stuck out of the water for 3 - 5 seconds before I can shut it off. Just dont want to be throwing away pump after pump...

 

[GA_Boater]

What about the busted water tube? Is the tube internal?

Impellers don't go bad from 3-5 seconds out of the water. It takes longer, especially when it was in the water before the hit.

What is the model number?

 

[Chrisravosa36]

Oh, ok. 217-58991, it looks like the tube snapped from the previous owner, it was a rough edge and is higher up into the midsection thank normal.

 

[GA_Boater]

Water tube is PN 96549 or ES96549 for the ESKA version. Less than 15 bucks.

Impeller is 96616 or ES96616 for ESKA for about 30 bucks. You might find it cheaper.

Sears prices are higher and those prices ^^^ are not from Sears. Google will find the parts.

If you need other part numbers, try this - http://www.searspartsdirect.com/model-number/21758991/0247/1305320.html

 

[Chrisravosa36]

Thanks for your help! If the motor was run for an hour or so, 30 mins at a time could that cause any major damage to the motor? Its air cooled head and water cooled exhaust. Its about 30 degrees when I run it. What kind of damage would it cause if it was run without water?

 

[GA_Boater]

I don't know how important the water cooled exhaust is or if any of the motor is cooled. Looking at the Column Assembly, which is is the midsection and lower portion of the motor, there appears to be a water cooled expansion chamber. If that is not cooled, it may lead to overheating the rest of the motor.

Hot or cold weather only means a few more minutes of running before the whole thing overheats. I would cool it as designed.

 

[Chrisravosa36]

Ok, Il look into the pump, thanks for the info!

 

[lmuss53]

I've never had any trouble with mine but my mechanic told me that the pump had to be working because it pumps a stream of water against the bottom of the block and then does whatever water does in 2 stroke exhaust to help keep the motor cool. There are no internal water passages in the block but the pump and the water it provides are essential. A stump bumping the motor up out of the water for a second is not going to interrupt the flow long enough to hurt anything. The tube you think is broken may be just fine, I don't think it goes into the block anywhere.

 

[Chrisravosa36]

Im getting the water pump today, I just dyi welded a new tube in their.

 

[lmuss53]

Sounds good, I wouldn't mind seeing a picture or two of the inside of that lower leg.

 

[Chrisravosa36]

*sigh I wish I could.... that thing was a PAIN to get back together. I can explain to you what it looks like if youd like, there is also a video "How to replace an eska waterpump" on youtube that show the inside of the LU.

 

[lmuss53]

No worries, I'll just keep hoping it putts along like it has for years.