1957 Fleetwin Problems

[BSDenning]

I've got a 1957 Evinrude Fleetwin 7.5 hoursepower (Model # 7522) that I recently bought on a 14 ft. jonboat. The motor only runs on the top cylinder. I've replaced both coils, contact points, and condensors. It didn't help. I switched out the spark plugs and it still runs the same. I double checked the gaps on both the spark plugs and the points. Spark plugs have a .030 in. gap and points have a .020 in. gap. Both spark plugs will spark, but I'm wondering if the bottom spark may not be strong enough to ignite the fuel. (I've got an owners manual and a service manual that I've been studying)

I took it out on the river and ran it today. It will run, but because it's only running on the top cylinder, it runs very slow and knocks off if you throttle down much. While running the motor at full throttle in forward, every now and then you can hear the bottom cylinder fire. I was confident that after replaceing the coils, points, and condensors, it would run correctly on both cylinders, so now I am very perplexed. If anyone has any suggestions, I would greatly appreciate it.

PS The only other thing I can think to replace is the spark plug wires. But visually, they seem to be in good condition to me.

 

[BSDenning]

Re: 1957 Fleetwin Problems

I forgot to say:

The reason I know it it only running on the top cylinder is while the motor is running, if you pull the sparkplug wire off the bottom cylinder, the motor continues to run with no change in the sound or RPMs. But, if you leave the bottom spark plug wire in and pull the top one off, the motor dies.

I was just checking both sparkplugs to see if they would each spark when I pull the rope while they are grounded to the head. The top spark plug sparked good. The bottom spark plug wouldn't spark at all. Then I noticed a drop of something on the spark plug between the gap. I blew it off and then pulled the rope and it sparked fine. I don't know if that drop of liquid was gas or water. I really hope it wasn't water. Any ideas on how to tell if it's gas or water?

 

[BSDenning]

Re: 1957 Fleetwin Problems

OK, I just went and bought an "In-Line ignition spark checker." It is a tool that you connect between the spark plug and the spark plug wire and when you pull the string, it will light up when the spark goes through it. It showed a good spark on each wire.

 

[tashasdaddy]

Re: 1957 Fleetwin Problems

i suggest you check compression on the bottom cylinder. you only have one carb, that feeds both cylinders, and the top is running, so it is not the carb, you have good spark, leaving compression.

 

[BSDenning]

Re: 1957 Fleetwin Problems

Ok, I followed your advice. I checked the compression. 60psi in the top cylinder and 20psi in the bottom cylinder. Then I found out the problem. I ran the motor without the bottom spark plug. A nice mist of water, gas, and oil sprayed out of the bottom cylinder spark plug hole. This can't be good. Is there any reason to keep messing with a motor that is getting water in the bottom cylinder?

On the bright side, the motor ran better without the bottom spark plug in it. Probably because the top cylinder doesn't have to work to pressurize the bottom cylinder. I could just run it like that. The bad thing is I'd be spewing gas and oil everywhere I go. I'd probably get some strange looks from other boaters.

Any suggestions?

 

[freddyray21]

Re: 1957 Fleetwin Problems

both reading are low. The 60 is enough to fire, but 20 is not. Pull the head and look at the gasket. You can also pull the covers of the side and look at the cylinder walls and rings. Might just need a new head gasket. If you can get both up to around 80-100 and within 10% of each other it should run smooth.

 

[BSDenning]

Re: 1957 Fleetwin Problems

Thanks for the info. The next thing I plan on doing is pulling the head and checking the head gasket. I'll let you know of any developments.

 

[BSDenning]

Re: 1957 Fleetwin Problems

I'm amazed that an alternate fireing motor will even run on 1 cylinder with low compression. (60psi) I talked to a friend of mine who is pretty experienced with boat motors. He said that there is 2 things that can allow water into the cylinder: 1. a blown head gasket or 2. a blown water jacket. I'm hoping that the problem is the first one and not the second one. If it's a blown water jacket, I'm assuming I now own a "parts motor." But, I'm going to pull that head some time this week when I get some free time. I'm hoping the only problem is a blown head gasket.

In the event that I find it is in need of new rings, how hard of a job would it be to replace the rings? I'm a beginner at boat motor repair. This is the first boat motor I've ever worked on.

Thanks

 

[F_R]

Re: 1957 Fleetwin Problems

If it has been ingesting water for very long it could be a parts motor. There's more to it than just rings.

Could be the head gasket. If not, the baffle plate on the exhaust cover probably has a pin hole through it, squirting water in the exhaust ports.

 

[R.Johnson]

Re: 1957 Fleetwin Problems

A blown head gasket is not at all uncommon on this engine, replacing it will probably fix the problem.

 

[samo_ott]

Re: 1957 Fleetwin Problems

Any update? Hope it's the head gasket. Sounds like it.

 

[BSDenning]

Re: 1957 Fleetwin Problems

I haven't pulled the head off yet. I've been gone all day today. I plan on studying my service manual tonight to figure out how exactly to pull the head off. Then tomorrow I'll go to NAPA and order a new head gasket. So, I'll probably pull the head some time this week.

One question: I was talking to a friend of mine and he said that if I pull the head off, I need to take it to a machine shop and have it sanded or planed or something in order to make sure that it will make a smooth seal before I replace the head gasket. Is this necesarry?

 

[freddyray21]

Re: 1957 Fleetwin Problems

you manual should show you how to true up a head using the figure 8 method and some sand paper. It will work just fine. Did one on a 35hp this last winter. 120 lbs both cylinders

 

[BSDenning]

Re: 1957 Fleetwin Problems

Is it possible pull the head without taking the motor completely apart?

I was reading my service manual and it only shows how to completely take the motor apart to overhaul the entire powerhead.

Also, what grade of sandpaper would you suggest using to true up the head?

 

[wbeaton]

Re: 1957 Fleetwin Problems

Go to the following website and read everything about repairing a 5.5 hp, which is basically the same as your 7.5 hp. In there, you will see how to prep the head and more. Its a very simple motor to rebuild so don't be too concerned. PM me your email address and I'll send you the parts manual to a 1956 Fleetwin.

http://www.outboard-boat-motor-repair.com/

 

[BSDenning]

Re: 1957 Fleetwin Problems

Thanks for the info. Your website is very informative! The parts manual is helpful too.

I have one question about replacing the head gasket. Do I need to use any type of glue or just put outboard motor oil on it?

 

[BSDenning]

Re: 1957 Fleetwin Problems

UPDATE! I pulled the head and the head gasket is definitely blown! I've ordered a new head gasket from NAPA and it should arrive on Thursday morning. So, I'd say on Thursday night I should give you an update with how it runs and the compression.

A few questions:

1. Do I need to use any glue on the new gasket, or just rub some outboard motor oil on it?

2. Once I have installed the new head gasket, how long should I wait before I crank the motor up, or can I crank it up immediately?

Thanks for all the help you guys! This forum is awesome!

 

[jbjennings]

Re: 1957 Fleetwin Problems

Good news about your head gasket!
I don't think you'll need anything on your head gasket. Just make sure the mounting surfaces are clean and you retorque the bolts to the right spec and in the right pattern.
Good luck!
JBJ

 

[BSDenning]

Re: 1957 Fleetwin Problems

I've sanded down the head. Should I also sand the block?

 

[wbeaton]

Re: 1957 Fleetwin Problems

No. Don't sand the block. No sealant is required. I look forward to the hearing your Thursday update.