Had hoped to avoid this like the plague.

[macawman]

I think we made some progress with the seafoam soak. After blowing as much of the seafoam out as possible, I reinstalled the plugs and...

1. Motor actually started with the throttle in the start position, and on the third pull yet. Only ran for a few seconds. Never done that before.

2. Motor would start on full throttle and continue running, but with a bit of a stumble.

3. After running at high speed until the motor was warmed up, I was able to throttle back to medium speed and continue running. However, the smoke coming from that thing was unbelievable. I had to shut the motor down because I couldn't see anything. Hope that was due to burning off the seafoam. If it's going to smoke that bad all the time, I'll have tree-huggers storming my house.

4. You should see the crap that washed out into a fresh fill of the test drum.m

 

[Pappy]

Yes, that was from the treatment.
Now you need to pull fresh compression numbers.

 

[macawman]

Did that before installing the plugs. Only a slight improvement. Both cylinders up about 5 psi.

 

[Weldorthemagnificent]

I would borrow a compression tester from a small engine guy before I tore that motor down. Small displacement piston port engine will use half its oomph overcoming the spring on an automotive gauge. I have a chainsaw that reads 120 on an automotive gauge and 155 on the gauge at the saw shop.
And yeah, those old engines don’t make you feel very good about your environmental footprint! They smoke pretty bad until warm and the garbage can looks like the Exxon Valdez drive through it!


Sent from my iPhone using Tapatalk

 

[macawman]

Checked compression again with a second gauge known to be accurate. Unfortunately, it simply confirmed the readings of the first gauge, do there is definitely a compression issue. Not surprising, I guess, for a 62 year old motor.

At any rate, I'm not going to mess with it any longer. I ordered the gasket sets, rings, valve leafs, leaf stops and a new impeller today for a power head rebuild. Will evaluate pistons, rods and associated bushing/bearings once I get the pistons out. I have not located a source for new connecting rod needle bearings so I'm a bit concerned about that.

 

[Stumpalump]

I drug home another 15 Evinrude yesterday and it came with a free 1970ish 9.5 johnson. The 9.5 was in good shape and it had good spark. No start so I cleaned the carb. No start and no compression. I soaked the cylinders overnight in sea foam and still no start. Pulled the head and the gasket was good so I kept spraying the pistons and thumped them with a soft leather mallet to free the rings. The sea foam is weak but after a day of soaking and thumping it fires on the first pull. I would have thought the carbon on the piston would whipe right off with all the soaking but not even close.

 

[macawman]

The chemicals did seem to help as the motor actually starts and runs, but nowhere near where I would want to be out on the river with it.

 

[macawman]

Sometimes these manuals just confuses the issue. The parts catalog breakdown diagrams shows the connecting rod needle bearings being uncaged, but the diagrams in the maintenance manual show the caged in 2 sets. Anyone know which is correct?

 

[Pappy]

As I said before....Seafoam is pretty weak.
At this point why not pull the cylinder head first and see what there is to see and report back.
Pretty sure you will be able to re-use the needles unless the engine was submerged.

 

[macawman]

I've pulled the head, Pappy, and I'm not really seeing anything one would expect to see in a motor this old. There were no apparent problems with the head gasket. There was no measurable warpage in the head and the head was magnifluxed for cracks. There is the usual ring of carbon around the top of each cylinder above TDC, and a accumulation on the pistons tops. Visible portions of the cylinders have some glazing but no signs of scoring or other physical damage.

My concern about the needle bearings is having them go everywhere if they are not caged when I pull the rod end caps off.

 

[Pappy]

Do me a favor. With the head off the block I want you to turn the crank until a piston is part way on the down stroke. Take a tool or your fingers and, while holding the crank in position, push the piston down and see if there is a lot of movement.

 

[macawman]

Raining cats and dogs right now, but I'll do that in the morning when the rain let's up.

 

[macawman]

Pappy, I tried it several times in both cylinders and at varying positions in the down stroke and could not detect any piston movement in either cylinder.

 

[Pappy]

Okay. That vintage engine had a bit of a history in the wrist pin area. Pilot holes in the pistons would go oblong allowing the wrist pins to loosen. Thought that may have been a contributor to low compression.
If rebuilding that is good to know that they are apparently in good shape.

 

[macawman]

Thanks, Pappy. I'll double check for that when I get the pistons out.

On a side note, these things didn't come out of the factory with helicoil inserts in the spark plug holes, did they?

 

[Pappy]

No. And Heli-Coil would not be my first choice as a repair.
Am thinking you may want to go to www.aomci.org and post in the "webvertise" section that you are in need of a good powerhead. May be cheaper in the long run. Rebuild yours down the road. Fun project if nothing else.

 

[macawman]

No hurry, Pappy. I want to make this one work
Stubborn that way, I guess.

 

[macawman]

I've read that the carbon oil seals at the top and bottom of the crankshaft are virtually indestructible and do not require changing unless there is obvious damage
Any truth to that?

 

[Pappy]

Yep....and you cannot get them anymore as far as I know either so take care of them. If I were you I would look up the number for oversize pistons and bore the block for them instead of just honing and re-ring. Source pistons through ebay or ??.

 

[macawman]

Thanks for the info, Pappy.

I thought about the oversized piston option, but evidently you can not bore out the 10 horse cylinders. It also appears from the manual that there are not and never have been oversized pistons for this motor. I am finding used standard sized pistons on eBay, but have no reason to believe they are any better condition then the ones I have. The cylinder bores mic out at exactly factory specs, but the current pistons are .002 over maximum piston-to-cylinder clearance so I would seriously consider boring if I could find the oversized parts.