Can you offer some places to start with my 79 Johnson 55 problems?

[BillaVista]

I have two problem conditions - may be related, or may be two separate issues.

Condition 1: Engine hard to start if it isn't dead cold or thoroughly warmed up, has rough idle (drops a few hundred rpm them recovers - don't know if it is "stumble" or a "miss"), and most recently has taken to stalling when put in gear (forward or reverse) even if warmed up.

History: Has always (since I purchased at beginning of this summer) been hard to start if it isn't dead cold or thoroughly warmed up, but I originally attributed this to my ignorance of procedure (use the start lever or not? prime again or not? choke or not?). If it is dead cold and I put the start lever to start and push key for choke, it fires first time. But if it quits before thoroughly warmed up is is a complete $%#@ to try and re-start - I have tried all manner of combinations of prime/lever/choke.

But if it started and kept running it ran well and good performance.

More recently, it has begun to stumble/miss at idle - almost quits but recovers. Never at rpm, just at idle. Sometimes it does just quit.

Most recently, it has begun to stall and quit when being put in gear, even if it has warmed up fully.


Condition 2: I noticed what seems to be excessive oil in the bottom of the compartment, seems to originate from the air box. If it were a car/truck I would suspect excessive crankcase blow-by, probably caused by worn rings / scored cylinder walls. Don't know if that is a good assumption for this 2-stroke OB?

Spark seems good, have changed plugs 3 times, plus always seem a bit oil fouled. Also seems to me to be excessive oil at the spark plug hole but then again, I have little experience with OBs so no real frame of reference.

I figure a carb rebuild is in order first, then a thing I think is called "link and sync" (kind of a boat motor tune-up I believe).

The oil I'm not sure about - I guess I could pull the head and have a look at the piston/rings/cylinder walls.

Does any of this sound familiar or common? Any other places to start?

Here are some pics of the oil in the housing:

As seen from port side:

As seen from stbd side:

 

[Daviet]

Re: Can you offer some places to start with my 79 Johnson 55 problems?

1. it sounds like you are on the right track with overhauling the carbs.
2. There should be a small hose on the bottom of the air silencer that runs to the block, is it attached to the block?

 

[iwombat]

Re: Can you offer some places to start with my 79 Johnson 55 problems?

It appears as though the oil is running out of the air silencer. As mentioned above, there should be a scavenge tube from the bottom of the airbox to the block. It's basically there to get rid of any excess oil in the airbox and send it into the block (it's really not a big deal if it fails to do its job). 2-strokes don't have any pressurized oil passages, so blow-by doesn't really happen. Carb rebuild and link&sync are two very good things to do straight out of the gate. Carbs are fuel delivery as well as lubrication delivery, and they've gotta be working correctly or you'll have a very short-lived boating experience.

Clean out the scavenge tube (and check the airbox outer gasket) if you're worried about the oil. Otherwise, you can just follow the sheen back to the dock at the end of the day.

 

[BillaVista]

Re: Can you offer some places to start with my 79 Johnson 55 problems?

Yes, the small hose was attached between the air silencer (thanks for teaching me the right term!) and the block. However, it's a little old and the fit to the plastic nipple on the air silencer didn't seem very tight (the end of the hose is belled out).

Are you guys saying the scavenge is FROM the air silencer TO the block? Here I was thinking it was from the block to the air silencer (i.e. to scavenge crankcase vapours from the block back into the air silencer and then into the carbs for combustion!

Question: How does the oil get into the air silencer in the first place?

'Nuther question - and this might just be one of those darn coincidence things. I was trying to run the motor to warm it up to do a compression check, and I tried the muffs and then with the lower end in a large bucket (a big old cooler, actually). But I didn't get any stream from the tell-tale. I put the muffs on over the inlet holes (I think!) - the holes indicated by the red arrow in thie following pic. And in the cooler-bucket - the water level was up to the red line:

Am I doing something wrong or has the water pump chosen an inoppertune time to go south?

The line from the block to the tell-tale outlet seems secure and no water pooled in the powerhead housing.


Oh - I have to fix the excess oil leak because the boat's dock is also my wife's fave fishing spot and she hates when gas or oil gets in the water:

 

[iwombat]

Re: Can you offer some places to start with my 79 Johnson 55 problems?

Take a weed-whacker line and chase it up the tell-tale hole. It may just be a clogged line.

The scavenge line actually goes from the silencer into the intake manifold. There's always a little blow-back through the carbs before the reeds close up all the way. That puts a little fuel into the air silencer. Fuel has oil .... I think you get the picture. Unlike a 4-stroke, fuel & oil mix travels throughout the ENTIRE (pressurized) crank case. Once air& fuel get past the intake reeds, the only way out is through the exhaust ports.

 

[BillaVista]

Re: Can you offer some places to start with my 79 Johnson 55 problems?

Pulled the tell-tale hose off - it's clear from the elbow at the block to the outlet orifice. Still no stream though :grumpy:

 

[iwombat]

Re: Can you offer some places to start with my 79 Johnson 55 problems?

Pulled the tell-tale hose off - it's clear from the elbow at the block to the outlet orifice. Still no stream though :grumpy:

Yeah, that's not good. Sounds like a water pump went out on you. If you're going to run it in a bucket, the water level needs to be a few inches over the upper fin.

 

[bonzoscott]

Re: Can you offer some places to start with my 79 Johnson 55 problems?

Just to add, from experience: When using ear muffs on 2 stroke out board, the vibration and jerking of a cold motor when starting can mis-place those ear muffs, essentially smoking the impeller. Either use a tub, duct tape the crap outta it, or have the wife hold 'em on good.

 

[BillaVista]

Re: Can you offer some places to start with my 79 Johnson 55 problems?

Thanks guys.

Tomorrow I will try and find a deeper bucket and if there's still nothing I guess I'll pull it apart and have a look at the water pump / impeller.

 

[BillaVista]

Re: Can you offer some places to start with my 79 Johnson 55 problems?

Well, the good news is, there's nothing wrong with the water pump / impeller. Turns out a deeper bucket was needed. Has good strong flow now.

 

[BillaVista]

Re: Can you offer some places to start with my 79 Johnson 55 problems?

The not so good news:

plugs (only a few hours on them):

upper cylinder plug hole:

lower cylinder plug hole:

 

[BillaVista]

Re: Can you offer some places to start with my 79 Johnson 55 problems?

upper cylinder compression

upper cylinder compression after couple oil squirts

lower cylinder compression

lower cylinder compression after couple oil squirts

 

[BillaVista]

Re: Can you offer some places to start with my 79 Johnson 55 problems?

Questions:

1) Could this be the cause of my poor idle (stumbles and drops a few hundred rpm), stalling when going into gear, and hard to start if not dead cold or thoroughly warm?

2) Is there any point doing a carb rebuild / link and sync before correcting this?

3) What are the chances it's just the rings that need replacing (and not a piston replacement and cylinder bore required)?

 

[Daviet]

Re: Can you offer some places to start with my 79 Johnson 55 problems?

I would start with a good decarb, if that doesn't improve the numbers, pull the head and take a look at the cylinders for scoring.

 

[iwombat]

Re: Can you offer some places to start with my 79 Johnson 55 problems?

^^ this

 

[Bosunsmate]

Re: Can you offer some places to start with my 79 Johnson 55 problems?

I wouldnt of thought it would cause intermittent loss of rpm at idle, but happy to be taught otherwise.
'
try pulling a ht line and grounding it to see if you can isolate the power dropping out to one cylinder

 

[BillaVista]

Re: Can you offer some places to start with my 79 Johnson 55 problems?

I would start with a good decarb, if that doesn't improve the numbers, pull the head and take a look at the cylinders for scoring.

Will do. Thanks for the suggestion.

Question - is a "decarb" possible in a bucket or do I need to put her in the water?

 

[BillaVista]

Re: Can you offer some places to start with my 79 Johnson 55 problems?

try pulling a ht line and grounding it to see if you can isolate the power dropping out to one cylinder

That's a good idea - I wonder if the symptoms will be masked by running on only 1 cylinder or not? Still - worth a try I reckon.

Here's a short video of the idle issue - you can see / hear the motor drop rpm, shudder, and almost quit and then recover. In the tach shots (sorry about the glare) you can see the drop in rpm.

 

[iwombat]

Re: Can you offer some places to start with my 79 Johnson 55 problems?

You can do a decarb in the bucket. It's gonna smoke a WHOLE LOT, so be prepared for that. There should be some pretty clear instructions for doing a decarb someplace around here.

Listening to the vid, it sure sounds like a missfire to me. Might want to check the condition of the wires in the whole ignition system to see if they've been rubbed bare someplace. Also, try separating your plug wires a bit more to see if the wires are leaking across.

Might even want to run it in the dark and see if you spot any arcing.

 

[BillaVista]

Re: Can you offer some places to start with my 79 Johnson 55 problems?

Thanks iwombat - I'm going to tinker a bit more tonight in the bucket - might even get some Sea Foam through it.

Should be ok with the smoke - I once had to tip the John Deer mower on its side after wifey ran over some dog toy that fouled the blades. Was on its side for a while - boy did it smoke when I started it up! I was lucky I didn't hydrolock it!