Help! front seal?
06-15-2012 | 02:46 PM
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From: Helena,
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Help! front seal?
I have a rjl 61 engine that I just got done replacing the bearings and crankshaft in. I just started it up and I have oil running out of the front bearing. There was a very small leak out of the front seal before I changed the bearing but now it is literally running out as the engine is running. It is a rubber seal bearing from rcbearings and the bearing looked fine when I put it in. What would cause the fuel to run out of the front bearing? I am going to disassemble it now and see if everything looks good. Any body know if this is an obvious problem?
06-15-2012 | 03:21 PM
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From: Helena,
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RE: Help! front seal?
So my problem must be that the case is worn out. Is there anyway to fix this problem other than buying a new case. I was thinking back to high school auto mechanics and remember that when the valve guides on engines got too worn we had a tool that would run a spiral machine mark down the guide to make it a little tighter. If I could chuck this in my lathe and run a machine mark several places around the case on the inside where the crank goes through, do you think that might work. I would of course have to run the lathe backwards from a cut so that the metal actually was scored (deformed) instead of being cut. If the interference is too tight when done, will the engine running wear it down so to speak so that there is not a lot of friction after running a bit? What say yee all? I don't want to throw this engine away now because with the crank and bearings, I have just passed the getting ticked off stage and I am going to make this engine run come high water but don't want to through any more money at it.
06-15-2012 | 04:11 PM
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RE: Help! front seal?
ORIGINAL: flybyjohn
So my problem must be that the case is worn out. Is there anyway to fix this problem other than buying a new case. I was thinking back to high school auto mechanics and remember that when the valve guides on engines got too worn we had a tool that would run a spiral machine mark down the guide to make it a little tighter. If I could chuck this in my lathe and run a machine mark several places around the case on the inside where the crank goes through, do you think that might work. I would of course have to run the lathe backwards from a cut so that the metal actually was scored (deformed) instead of being cut. If the interference is too tight when done, will the engine running wear it down so to speak so that there is not a lot of friction after running a bit? What say yee all? I don't want to throw this engine away now because with the crank and bearings, I have just passed the getting ticked off stage and I am going to make this engine run come high water but don't want to through any more money at it.
So my problem must be that the case is worn out. Is there anyway to fix this problem other than buying a new case. I was thinking back to high school auto mechanics and remember that when the valve guides on engines got too worn we had a tool that would run a spiral machine mark down the guide to make it a little tighter. If I could chuck this in my lathe and run a machine mark several places around the case on the inside where the crank goes through, do you think that might work. I would of course have to run the lathe backwards from a cut so that the metal actually was scored (deformed) instead of being cut. If the interference is too tight when done, will the engine running wear it down so to speak so that there is not a lot of friction after running a bit? What say yee all? I don't want to throw this engine away now because with the crank and bearings, I have just passed the getting ticked off stage and I am going to make this engine run come high water but don't want to through any more money at it.
06-15-2012 | 05:40 PM
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From: Helena,
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RE: Help! front seal?
Ok, thanks w8ye, I thought of that when I was setting up the tooling. I already did it and got it back together. If I had a small wheel it would have been better, however I did it with my boring bar with the lathe turning backwards. I turned it at about 52 threads per inch. I could have gone a little courser I guess. The process did take off a small amount of material, however it did close up the gap some and now it just barely seeps when running. Out of a half tank of fuel I only had residue that formed a drop. We will see if it gets worse with time. We will see how it runs tomorrow morning. Thanks for the tips.
06-15-2012 | 06:49 PM
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RE: Help! front seal?
Ok, if the engine is running fine, idles well, runs good at WOT, don't worry about it. Most all of my 2 stroke engines ooze oil out of the front. it actually keeps the front bearing lubricated much better and helps flush out any dust or debris that get into it. A number of years ago some companies started catering to those users who wanted less messy engines. But before then all the engines oozed oil out the front. Bushing engines still do so today and some brands still use open bearings without seals on them. The front bearing lasts a lot longer if it gets a steady flow of oil through it too. I tend to worry a lot if oil isn't oozing out of the front bearing area on my engines.
06-16-2012 | 04:15 AM
#9
RE: Help! front seal?
Sounds like you did the right thing. If it still comes out real bad you can file or broach a fine channel from the front bearing to the carb opening so the intake suction sucks the excess into the motor. This is done on the casting. Some manufacturers do this at the factory. It can also be done with a small hole behind the bearing and into the carb opening. If it is too big of a hole/gap it can affect the idle. I have had to solder up the bearings on a Thunder Tiger .07 just to seal it better. Kind of a pitiful machining job they did. I have made brass bushings for Baby Bees too because they wouldn't hold a setting after running little props for too many races.
06-16-2012 | 09:16 AM
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From: Helena,
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RE: Help! front seal?
Hobbsy, it looks like there is a spiral ground into the crank on that picture. Aspeed, my engine case did have a straight groove in the upper part of the case from the carb inlet to the front bearing with a recessed grove around the front of the case just behind the bearing. I assumed this was to lube the front bearings. With the spirals I put in the case from the front to the back, it seems to be helping out quite a bit. It went from drip, drip, drip, drip, to just one or two drops on the lower part of the engine case in about 5 minutes of running. At idle, I don't see any coming out. I am guessing that since the crank was cracked in the intake area, it wore the case slightly and caused excess clearance. With the spiral I ran, it closed up the gap slightly and also helps to pull excess fuel from the front to the back of the engine. It is still getting lube in the front however as I can see a slight seep out of the bearing.
06-20-2012 | 09:52 PM
#12
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RE: Help! front seal?
They are full contact seals. He didn't say if he removed the inside seal which is the wrong thing to do with older engines. A lot of engine manufacturers kept the front of the crankcase too short for adequate sealing so they went with a sealed bearing.
ORIGINAL: Hobbsy
Those rubber shields are not the seals, the real seal is the fit between the crankshaft and the crankcase.
Those rubber shields are not the seals, the real seal is the fit between the crankshaft and the crankcase.
