1968 18 hp Fastwin

[wineslob1104]

Hi all. First post here.

I have a 68 18hp Fastwin with a HARD miss. Earth shaking. The first time it happened (boat was on the water) I thought I'd hit a rock or something. It only shows up once the engine is hot and happens about every 10 seconds. At lower RPM's it kills the engine. I've replaced: points, plugs, coils, rebuilt the carb.....no change. She starts up easily, until hot and then not so easy. The water pump appears to be working (water in exhaust and out the pee holes)

Any ideas?

Mike

 

[Scurvy Knave]

Re: 1968 18 hp Fastwin

Did you change the wires?

 

[wineslob1104]

Re: 1968 18 hp Fastwin

:facepalm:

No. Is there a thermostat? Just in case.

 

[kfa4303]

Re: 1968 18 hp Fastwin

Hi wineslob. Welcome to iboats. Yes there is a t-stat located on the top lef corner of the powerhead. However, the fact that miss occurs once the motor is up to temp means your probably dropping a cylinder due to a failing ignition component. You'll need to pull the flywheel to inspect them. They can look good, but still be bad. You may have a loos coil wire and/or failing condenser. Thankfully, it's a simple DIY jobs and you can get any and all parts you may need right here at iboats. Here's a great link that can walk you through a tune up from top to bottom.

Maintaining Johnson E & FD Serie

 

[F_R]

Re: 1968 18 hp Fastwin

Except for a couple of statements you made, you are describing the classic symptoms of a worn out clutch dog. "Hard miss", "feels like hit something", "shakes the whole boat", periodically as "every so many seconds"...all those describe a clutch dog. It is coming out of gear, rotating 1/2 revolution, and slamming back in gear. Till it happens again. And again. Watch the shifter handle when it happens. Does it jerk or jolt? Clutch dog.

Now, as for killing the engine when it happens, and hard starting, that may be another issue.

 

[wineslob1104]

Re: 1968 18 hp Fastwin

F R that may make sense.

I should have added condensers to the parts that were replaced.

The motor sat for almost a year after I went through it. I had a VERY hard time getting it to go in gear. I'll run it again in neutral, if that would keep the possible part in question from "doing it's thing"? Would low oil level in the lower unit cause/contribute to this?

Thanks for the help guys.

 

[kfa4303]

Re: 1968 18 hp Fastwin

Ahh, if you're having trouble getting into/out of gear and it also has the tell-tale violent jerk as if you'd hit a submerged object, then it is almost surely a worn clutch dog. The only way to be sure will be to drop the lower unit and open up the gear case. If the clutch is bad, you can get a new one from several sites including marineengine.com, ebay although I was able to get a new clutch, propshaft and set of gears for less than the price of a retail clutch by placing a WTB ad on aomci.org. While you have the gear case apart, you may as well reseal the lower unit too. You can get a reseal kit for about $25. You'll also need a tube of 3M 847 gasket sealant. Here is a link that can walk you through the job. The clutch simply slides on/off the propshaft like a ring on a finger.


http://forums.iboats.com/johnson-evinrude-outboards/fastwin-lower-unit-seal-faq-277190.html
1968 Evinrude 18803A 18 hp Outboard Motor Parts

 

[wineslob1104]

Re: 1968 18 hp Fastwin

kfa...TY.