omc A motor

[calvin]

New to me evinrude A motor. Powerhead turns free but......gearcase will not turn. Filled with gear oil ....none in it......and let it set.....What to do next?

[Ron Hill]

Post some pictures. There are several people on BRF that can help you witht he gearcase.

Where do you live?

[Smokin' Joe]

Did it have water in it? Shoot it inside with Liquid Wrench, be sure it gets to all bearings. Let it sit. If you can't turn the driveshaft later with vise grips then
tear down the gearcase.

[calvin]

No water....nothing?.....Filled with wd and thin oil......let it set......we will see.

[HGipson]

Liquid wrench and Marvel Mystery oil use to always work for us when we rebuilt large Diesel engines. That should help break that lower loose.

[champ20B]

New to me evinrude A motor. Powerhead turns free but......gearcase will not turn. Filled with gear oil ....none in it......and let it set.....What to do next?

Whatever you do, dont turn it. There could be broken debris or rust that could break gear teeth and or damage salvagable components inside. Look on the internet for an OMC class "A" racing engine manual. There are outfits that sell downloadable manuals for many stock outboards like yours in particular, racing bikes, racing cart engines ect.
I found one for a Blue-Streak Champion HotRod outboard a long while back this way. When you get your manual, study the drawings carefully to understand how it is constructed and read everything. Take the case apart and inspect it. Youll find the problem and be able to fix it right. Don't go filling it with penetrant-oil and try turn it free then run it.

[calvin]

Still have it laid up with thin oil....Will not turn with light pressure.....Will take apart next.

[champ20B]

Still have it laid up with thin oil....Will not turn with light pressure.....Will take apart next.

Be sure to set the gear-case in every possible position (upside down, rightside up, ect) for a good period of time each, to be sure the oil gets to every part within the case. The penetrant oil should serve to help in dissasembly alone. This problem is likely a bearing that has froze. Either the driveshaft or propshaft bearing surfaces may need to be repaired or replaced. That is if corrosion at the froze up bearing point of contact has pitted or defaced the running surface of either shaft, but sometimes they may be o.k with a little fine sanding with 800-1000 grit cloth. Replace all of your bearings. If you cant find them available in the used or new outboard racing parts venue, try Granger or Motion Industries. They have seals and bearings of nearly every kind ever designed that will likely be of equal dimensions of your bearings and seals. Also, find out who's who in class "A" stock outboard racing presently, and which has extra parts. That will help also. Thats what I did for my 20 HotRod and my Yamato 80 in another class.

[Fastjeff57]

Gotta be rusted all the death in there. If the gear teeth and needle bearing surfaces of the shafts are not pitted with rust marks, they can be reused. The rest of the parts can be replaced with store bought items.

Jeff

[champ20B]

Be sure to set the gear-case in every possible position (upside down, rightside up, ect) for a good period of time each, to be sure the oil gets to every part within the case. The penetrant oil should serve to help in dissasembly alone. This problem is likely a bearing that has froze. Either the driveshaft or propshaft bearing surfaces may need to be repaired or replaced. That is if corrosion at the froze up bearing point of contact has pitted or defaced the running surface of either shaft, but sometimes they may be o.k with a little fine sanding with 800-1000 grit cloth. Replace all of your bearings. If you cant find them available in the used or new outboard racing parts venue, try Granger or Motion Industries. They have seals and bearings of nearly every kind ever designed that will likely be of equal dimensions of your bearings and seals. Also, find out who's who in class "A" stock outboard racing presently, and which has extra parts. That will help also. Thats what I did for my 20 HotRod and my Yamato 80 in another class.

If the shaft is pitted, there are machine shops that do welding on outboard drive shafts. The way it is done is by building up the bad area with weld, then they turn it down on a lathe to original specs.
Another suggestion I hope will help in restoring your motor, regards the piston rings and crank seals. Often times, although the powerhead turns smooth and has compression, it may have sat up for a long time. Two things are ALMOST always certain. For one, the seals will be hardened. They may seem a bit pliable, but trust me, they can wear a groove in your crank shaft ends. This is particularly present if the motor was run on todays ethanol-based gasoline and then left to sit for five or ten years. Next are the piston rings. Sometimes the rings may be stuck in the piston ring grooves. This is caused by oil-gasoline/ash residue that glues the rings into the grooves to where they cant move any or be removed from sitting up. It is like a tar or gunk. Running it like this will cause rings to break and result in significant cylinder wall damage. Your motor might not have any of these problems, but I suggest opening up the powerhead to be absolutely sure regardless. You can remove stuck rings by soaking the pistons in a bucket of carb cleaner. let them soak for a week. Each day during this process, try moving the rings in and out on the first loose part gently as not to break them. Keep this up until they get worked loose all around. This way you can keep those rings and use them unless you can get new ones. If new rings are available, just get the stuck ones out even if they get broke and replace them. Be sure to clean the grooves out. Also, if you suspect that your motor was ever run in salt water, check the water jackets for clogging. Oxidation of aluminum builds up and prohibits clear flow of cooling water. This is to consider if the motor came from the coast, having a stuck lower unit. This can be checked by removing the cylinder head, but that is an optional choice and not necessarily a must. Check the condition of your cylinders and check for wear (out of round).When you are ready to reassemble the engine with new piston rings, always hone your cylinders. Use as fine of a honing stone as possible like an 800 grit or so. Using as finer stone as possible helps to ensure better seating and best horsepower potential.When honing, only a little bit is necessary as not to over-do it. Just enough to just see a fresh surface is necessary. It is an old racers method. If you can, replace any old gaskets or make some with any available material that matches correct thicknesses. You will have a really nice Evinrude "A" racer when you are done that will be worth something!

[calvin]

Thanks f or the tips I will take my time and go over it totally. It was raced in the salt for a while.

[champ20B]

Thanks f or the tips I will take my time and go over it totally. It was raced in the salt for a while.

Your welcome! I enjoy helping enthusiast with any tips I can. One more thing I thought of when I saw that it was run in salt water was the tuned exhaust pipe inside the mid-section (tower) of your engine. When you pull the power-head from the mid-section, remove the tuned megaphone pipe. Check it for any corrosion damage. This is a simple horn shaped pipe that can be patched with welding. Often times, this part can be found on e-bay. What this component does is boost your engine's power via the process of deflecting sound waves from the exhaust as to pull extra air/fuel through the intake/induction of your engine all the way out through the exhaust. It then bounces the extra charge of this air/feul, that would have got away, off other existing sound waves back into the combustion chamber or cylinder. This is like a reverse super-charging effect that will increase induction and compression.If you have the 13.2 cubic inch version of the 15HP "A" racer, that is how OMC achieved so much power out of this little engine besides just having an excellent design overall. I assume that the later 15 cubic inch model had this feature as well. From what I have seen of the 13.2 cubic inch OMC, as a fishing motor at that, I can assure you that little engine had guts! The racing versions can hit 60 m.p.h from what the APBA states. You can see them on You-Tube videos on line in the "200cc modified outboard races". You'll be amazed! I remember running my Mark-25 Mercury on a 14 foot fishing boat at full throttle and seeing two guys in a equal sized boat with one of these little 15HP motors just about keeping up with me. The later 15 cubic inch version was just as good also, if that is what you have. Honestly, I believe these motors were in the 18-20 HP range in reality. Of all the engines OMC made up to 150HP, the 15 model had the best horsepower per cubic inch output ever. Let me know how it turns out when you're done restoring your engine.