1978 Johnson 115/hello again!

[JRegier]

Hey guys, long time no see! Just thought I'd come by and say hi. I didn't even get the boat in the water this summer, too busy with work! Anyways, I finally got a motor to replace the 1970 115 Evinrude I've got (Ignition system made me nervous and last time I launched her and started it refused to shift to neutral) and as per the title it's a 1978 115 Johnson with trim and tilt for $200. The guy I bought it from told me it was off a centre console and boy the electrical system is cut up and spliced together. Luckily my boat originally came with a 1978 85HP evinrude so I'm going to be swapping the stator and timing base, dumping some seafoam into the cylinders (I was told it was 110 on 3 cylinders and 90 on another), rebuilding the carbs and then putting Humpty Dumpty back together and giving her a start! I'll be posting some updates as we make progress. As well as pictures!
The timing plate arm was held to the throttle lever with a piece of copper wire, as an example of how this poor old girl has been neglected.

 

[Bosunsmate]

good luck, some of those stator/timing base screws need a bit of lock tite to hold them in from all the engine vibrations

 

[emdsapmgr]

Prior to running, you may want to have a look at the cylinder with the low compression. Pull the head and check out the head gasket, cylinder walls, piston crown-etc. A damaged head gasket could be the compression problem, a cheap fix. If you find it's ok, you still may want to run some Bombardier Engine Tuner through it a couple of times to see if the compression comes up somewhat. That engine new from the factory would have had 125 compression. Luckily, the ignition system on the 85 should swap to the 115 with no problem. The heads, pistons won't.

 

[JRegier]

Yeah going to be a few more days. Securing the timing base one of the screws appears to be stripped. May as well swap the upper bearing with the one from my 85hp and just put new o-rings and an oil seal on it.

I'm thinking I might pull the head and take a look after I find out which cylinder it is.

The block was trashed on the 85hp and only one of the pistons (already .030 oversized) was good. For some reason the idiot I bought the boat off of used automotive plugs and caused the engine to go boom. Piston seized in the #3 and the wrist pin broke right out of the piston and smashed up the cylinder wall.
Oh the things you learn buying the first boat.

 

[JRegier]

Cold compression numbers (yeah I know. Starting it isn't an option right now)
#1) 120psi
#2) 105psi
#3) 130psi
#4) 120psi

I'll be pulling the port head off tonight and let you guys know what I find.

 

[emdsapmgr]

If you are lucky, it's just a bad head gasket...

 

[JRegier]

If you are lucky, it's just a bad head gasket...

Never did have much luck. It LOOKS as though some of the piston is scraped into the cylinder wall and it feels like some very minor scoring. And naturally the block has already been bored to .020.
http://m.imgur.com/OBS21mE

 

[racerone]

Motor needs to be rebuilt again.----See this kind of damage all the time.

 

[emdsapmgr]

If you are lucky, you may find that some of the piston aluminum has deposited itself on the cast iron cyl liner. If so, you can carefully dissolve that aluminum by using some muratic acid. That will clean it off the cyl walls. If the cast iron walls are not gouged, you may just need to re-hone it and put in a new 0.20 over piston. (also 4 new ringsets.)

 

[JRegier]

Just out of curiosity; what typically causes this kind of damage? Lean condition in the one cyl?

 

[racerone]

Folks simply are not well versed in the operation / maintenance of outboards.-They will run with the wrong prop.-----Will go to full throttle without letting the motor warm up-----Will not maintain the water pump / cooling system.--Careless in mixing oil and gas as well.---The result is what you see.

 

[emdsapmgr]

Also possible that there is a problem inside the carb throat that feeds that cyl. If the main jet that feeds that cyl gets any debris in it, fuel will be restricted, causing that cyl to run lean. That means insufficient fuel and oil-a major reason for these types of failures. Pull the carb completely apart and do a complete visual inspection. (Pull all the jets out.) The original fuel hoses on that engine were not made to handle today's ethanol fuels. Over time, the fuel hose will break down and bits of black fuel hose will migrate down into the carbs and jets-possibly causing a restriction.