Had hoped to avoid this like the plague.

[Pappy]

That same source I gave you also has the information for an excellent shop that can and will bore small bore outboards. I have had bore work done by him and it has been excellent.

 

[macawman]

Yes, he mentioned that.

 

[nccatfisher]

I measured the cylinders at 45 degree intervals around the cylinder and at 5 or 6 locations up and down the cylinder. Premitive, I know but the best I have at hand. I feel pretty good about the cylinders, but the pistons are another matter. The cylinder could be good, but the piston worn out because one is steel an the other is aluminum.

Given that the rods, bearings, pins and pistons all have to be changed whether the pistons standard or over sized, the single answer to all the questions is to bore it and be done with it.

Maybe I should see if I can find a machine shop that will measure the block and pistons for me.

I believe I would. If it has mismatched pistons that means it already has been into once.

If there is any doubt I would bore it, then you are good to go from now on barring some unforeseen failure that could happen to a brand new one. It would be bad to have as much time and new parts in it as you do and find out later it did need just a little more attention that could cause a failure.

As an ending note, all that carboning up and plugging of exhaust is indicative of either tremendous low speed running, cold temp running or most likely it was already pumping a bunch of fuel/oil by the rings/pistons some way. It had issues, that is why I would check every possibility prior to going back with that block in the shape it is in now.

 

[macawman]

Yep, someone has been into it before. I've had to laugh at some of the shade tree stuff I've come across.

Just waiting on parts price and availability now.

 

[macawman]

Just curious. I have read the as little as 5 seconds without water can destroy the pump impeller. I've just replaced the impeller in my motor and having seen the composition of the impeller, it seems that it wouled last quite a bit longer then 5 seconds. Is it legit that it would be destroyed that fast?

 

[jethro]

Just curious. I have read the as little as 5 seconds without water can destroy the pump impeller. I've just replaced the impeller in my motor and having seen the composition of the impeller, it seems that it wouled last quite a bit longer then 5 seconds. Is it legit that it would be destroyed that fast?

Certainly a possability.

 

[macawman]

Thanks for the input, Jethro.

 

[Pappy]

There is a difference between damaged and destroyed. There are a myriad of variables involved here as well. Was the engine just run in the water then cranked again without? Was it run yesterday and cranked for a few seconds today? Has the engine not been run for a week, weeks, or months then cranked? Each makes a difference in how dry that pump cavity and impeller is. Was the impeller a new impeller or several years old?
With the old iron there is another variable. Those old pumps seem to have a constant supply of unburned fuel/oil running down the driveshaft and into the pump. Not good for the rubber but it is a lubricant and they seem to put up with it for a long long time.
Will running an engine out of water for 5 seconds destroy a pump? You decide.

 

[macawman]

Pappy, your posts are not always what I want to hear, but they are always interesting.

Was just curious about the pump. I'll know in the future that it will need to be checked out if I every accidentally run it without water. Just replaced the impeller, so I think i'm ok there. Current headache is a bent blade on the prop.

 

[macawman]

Solas props. Good, bad or down right ugly?

Opinions, please.

 

[nccatfisher]

I have heard plenty of bad, I am running a SS one on my 25 Yamaha right now with absolutely no issues at all. Of course you will get the there is no advantages in SS on a small motor and there isn't in performance. But where I run I would buy a new aluminum one every week or two. I just go right on with SS.

 

[GYPSY400]

Is this 16:1 oil spec with 1956 oil or 2018 oil? The reason I ask is that oil has come along way and running 40-50:1 shouldn't be an issue with a low revving ( <10000rpm) engine.
Just wondering if these old motors still need such a rich mixture.

Sent from my SM-G903W using Tapatalk

 

[BillPlayfoot]

Is this 16:1 oil spec with 1956 oil or 2018 oil? The reason I ask is that oil has come along way and running 40-50:1 shouldn't be an issue with a low revving ( <10000rpm) engine.
Just wondering if these old motors still need such a rich mixture.

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I was wondering the same thing. I have a 1956 10 horse Evinrude that I run 50:1 in and have never had a problem. It has been running fine for the last three years. When it does quit I won't repair it since they can be bought for $200 or less around here

 

[Pappy]

This is just the kind of "boat ramp wisdom" we need to be aware of.
The older engines can be run on the same original oil ratio (16:1) on todays oil but running them on a 50:1 mixture is killing the engine. These are plain bearings in the engine (non-roller) and old school straight soft aluminum pistons with three rings vs one pressure back and one standard ring. Tons of other changes occurred to allow engines to run successfully on a 50:1 ratio as well. Piston metallurgy (High sil pistons, semi-elliptical, etc) and fit, cooling system changes, cylinder head design changes, etc. Millions and millions were spent developing engines to run and last on lean oil mixtures.
The simplistic answer that oil is better these days never ceases to amaze me. When a guy doing this blows his engine on a lean mixture you never hear from the guy again. A bit more oil? or a blown powerhead and paddle home? Your choice.
Also, if you really knew what you were talking about as far as oils "these days" go you may realize that today's oils, protection wise, are probably not as good as the original TCW and TCWII oils which had better bright stock and additive packages. Those oils were built to protect engines internally back when the oils did not have to put up with the EPA, but EPA mandates came along and they could not meet some of the new standards so some of the "good stuff" had to go and was replaced. Engine industries had to adapt and change engines internally to be able to run successfully with these new mandates and new lubricants.

 

[macawman]

I've seen 16:1 mentioned before, but my manual says 24:1.

 

[Pappy]

Okay, well I guess a bit of clarification needs to happen here as well.
If your original engine manual says to run your engine on 16:1, 20:1, 24:1, 50:1, etc that is the ratio you want to run. OMC and 100:1 engines are the exception to the rule there as that was found to be not so good during off season storage and was brought back to a 50:1 mixture.

 

[macawman]

If the book says 24:1, would it hurt to try 16:1?

 

[GYPSY400]

This is just the kind of "boat ramp wisdom" we need to be aware of.
The older engines can be run on the same original oil ratio (16:1) on todays oil but running them on a 50:1 mixture is killing the engine. These are plain bearings in the engine (non-roller) and old school straight soft aluminum pistons with three rings vs one pressure back and one standard ring. Tons of other changes occurred to allow engines to run successfully on a 50:1 ratio as well. Piston metallurgy (High sil pistons, semi-elliptical, etc) and fit, cooling system changes, cylinder head design changes, etc. Millions and millions were spent developing engines to run and last on lean oil mixtures.
The simplistic answer that oil is better these days never ceases to amaze me. When a guy doing this blows his engine on a lean mixture you never hear from the guy again. A bit more oil? or a blown powerhead and paddle home? Your choice.
Also, if you really knew what you were talking about as far as oils "these days" go you may realize that today's oils, protection wise, are probably not as good as the original TCW and TCWII oils which had better bright stock and additive packages. Those oils were built to protect engines internally back when the oils did not have to put up with the EPA, but EPA mandates came along and they could not meet some of the new standards so some of the "good stuff" had to go and was replaced. Engine industries had to adapt and change engines internally to be able to run successfully with these new mandates and new lubricants.

Ok. Thanks for clarifying that.. I didn't know about the plain crank bearings as I've never had a motor that old apart. Also I didn't know about the old oils being better than the new stuff.. one would assume that newer is better as oil testing and technology improve, but your EPA reasoning explains that.
Good thing I asked as I would just run everything 50:1.. and I've been a mechanic ( not small engine) for 20 years.

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[Shaugh]

56 was a transitional year for using needle bearings. Some of the smaller motors were still using 16:1 and others were changed to 24:1. Many collectors believe that 10hp motor should be run at 16:1 because of the weak wrist pins.

The reality is that either mixture will work perfectly fine. Old outboard motors are very crude devices... They were designed at a time when people were not very good at following instructions....When I was a kid, my father used to judge the mix by color.... he'd just pour it in till it looked right...Gas quality could also be questionable.....nobody worried about Stabil back then.... because of that, they were engineered to perform within a very wide band of conditions. If it was me I'd just run it at 1 quart per 5 gal tank...... it's easier that way.... and the color will be near perfect...

 

[Pappy]

The old 7.5hp would be the only one I would continue to run a heavy mix in no matter what. Those engines would lose #1 rod if you looked at them wrong.