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Mumbles.
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April 22, 2024 at 4:05 pm #287204
Good afternoon. While i the lake running the 1955 RD17 I noticed the motor began to smoke and of course not exhaust oil smoke. Apparently the water pump was not pumping enough or no water at all. I shut down the motor immediately and the power head was very hot and would not turn over. I let the motor sit for sometime and it freed up. While I clearly overheated the ol’boy where do I go from here?
- I assumes pull the inspection ports, exhaust ports and head off to determine the amount of damage?
- Dive into why the impeller and pump failed?
- Would there be any damage to the crank or main bearings?
I did pull off the lower and the impeller is in good shape installed correctly and pinned so it seems to have been working. Could I have a clog in the water jackets?
Thank you for the input and hopefully I can save the motor I love that beast and use it on the fishing boat all the time.
Nick
April 22, 2024 at 4:51 pm #287205Just a suggestion,
Remove the watertube from the tower & check it for clogs. Maybe sometime in the past a blade from the impeller may have made it’s way in the tube or insect nest. Use a drill motor on the driveshaft to see if the pump is working using a cordless drill for safety 120 volts may be a schocking event!
Then connect a hose to the watertube to see if the block passages are clear. I’ve had to take the waterjacket off the cylinders to scrape the junk off of the waterjacket before. Hope this helps
April 22, 2024 at 5:36 pm #287210permanent damage may… have happened but it is to late now. I would just inspect and change impeller then run it to see what happens.
if pumping is restored great ! if not inspect PH water passages for broken fin parts
motor is 69 years old but tuff damage if any permanat is likely scoring of the cyl walls which you can inspect with a endoscope or if inclined to do so by just pulling the cyl.head. check compression before and after the new cyl head gasket is installed.
is this a restored beauty or a ugky duckling ?
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April 23, 2024 at 12:34 am #287221Well it is a bit of an ugly ducking but an awesome motor for me. I use it and have used it for fishing in Ohio for the last three years and she runs like a champ. I will one day restore it but for now it is my go to when i fish, Thank you for the input and suggestion will probably tear it down as i have in the past to understand the depth of the damage if any. Ideally on a motor of this age what should the compression be? Also if the is some scoring can it be corrected thru honing the cylinder walls? Is there a tolerance fro the bore and piston on this motor? thank you for the help
April 23, 2024 at 8:33 am #287223experts will chime in on possible cures but a minimum would be a new head gasket and a look-see of cyl walls. I have never cracked one open so I can’t say about the benefits of a rebore etec…
compression wise well foolks want big numbers (>100psi) all the time but me…. if it runs it is good enough say 75 -80 psi. very subjective problem ..
my 9622a Evinrude 9.5 runs great around 70 psi
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April 24, 2024 at 6:17 am #287268My experience with these old two-cycles is that they usually are just fine after over heating. Sometimes a leaf gets stuck over the water intake, or mud gets sucked in from the river bottom. Identify the cause, clean it out, and you are good to go!
Now, having the motor seize because of not enough oil is another issue…
Steve.
April 24, 2024 at 7:29 am #287275I have seen the intake screen for the water pump on this style OMC motor get plugged up, TWICE. Look carefully in the area of the screen and the bypass cover for debris. Otherwise, do what others have said and check for clear water passage through the motor and run it.
David Bartlett
Pine Tree Boating Club Chapter"I don't fully understand everything I know!"
April 24, 2024 at 9:25 am #287278Well the good news is cylinder look good top has a small score mark but not horrible. The cylinder walls are glass smooth should these be this smooth?
both cylinder 90psi so I think I may have got lucky on this one.
April 27, 2024 at 11:34 am #287378The cylinder walls are glass smooth
If they are mirror smooth, that’s just a sign of being well used over the years. Cylinder walls will usually show a bit of the factory honing, or cross hatch, even after multi years of use but if they are that smooth, it indicates some wear going on. How’s the lip at the top of the cylinder? Can you catch your fingernail on it? If you have a bore gauge handy, you can measure the taper of the cylinders to get an idea of the amount of wear without having to remove the powerhead.
If the cross hatch is worn away, the rings are probably worn an equal amount. Re-ringing the motor wont repair the worn cylinders and will probably result in lower compression than what the motor has now as they wont seat properly into the worn cylinders, which are probably egg shaped by now.
So if the cylinder walls and pistons don’t show any signs of damage, it might be best to reinstall the head with a new gasket and call it a day, otherwise you’re looking at a major teardown and possibly having to get the block bored to fit new oversize pistons and rings, if you can find them.
Richening the fuel mix from 24:1 to 16:1 might also help the motor to last longer. If the planets are aligned properly, your motor might have gotten lucky enough to survive the overheat without suffering any damage and the tightness would only have been temporary until it cooled down.
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