one way bearing

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crow2k80

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28
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I have had my savage for about a month and my one way bearing already went out. I hear from somewhere it is due to the pressure that builds up inside the engine when starting. so in this situation I have 2 questions:
1. Should I take the glow plug out and use the rotostart for 2 seconds to try to get rid of the pressure built up?
2. Has anyone else had any problems with this bearing?
 
hmmmm...the pressure building should have no effect on the one way bearing...nitro fuel (or more specifically, the oil in nitro fuel) seeps out the backplate and gets into the OWB...seal your backplate to cut down on that...the other trick I've heard is to sand the shaft on your backplate shaft...just to rough it up a bit, to help it grab...
 
What fuel are you using? The OWB is just a bearing that slides over a shaft. It's not inside the engine so pressure isn't an issie.
 
Fxstrongside said:
What fuel are you using? The OWB is just a bearing that slides over a shaft. It's not inside the engine so pressure isn't an issie.
Click to expand...

:bsflag:

Depends on the engine...some one way bearings are inside the block. (example-HPI 4.6, sts)
 
if you are trying to start it with a roto and you flood the engine that could have an affect on the life of the OWB, little trick is to loosen the plug slightly while starting then tighten it up once engine is running
 
thanks for all the help everyone.
I am running bryons nitro fuel 20%.
I just got a new one way bearing today, so I'll soak it in wd 40 and let it ride. I'll also do what fuel father said..with the glow plug trick.
 
i had a one way bearing break one time. i think that they are really pricey if i remember correctly. anyway i don't know about lubing that one way bearing because i had a problem where i spilled fuel wile filling my truck and it got on the one way bearing some how so the bearing slips on the shaft so it is very difficult to start. but i don't know just thought i would mention that.
 
crow2k80 said:
I have had my savage for about a month and my one way bearing already went out. I hear from somewhere it is due to the pressure that builds up inside the engine when starting. so in this situation I have 2 questions:
1. Should I take the glow plug out and use the rotostart for 2 seconds to try to get rid of the pressure built up?
2. Has anyone else had any problems with this bearing?
Click to expand...
Hey, crow. It sounds like you may have flooded the motor which makes for the back presure symptom, Yes, pull the plug and flip the truck upside down and pull the pullstart which clears the crank case of accessive fuel. Reinstall plug, then try to start it up. As far as one-way the bearing, I had the same thing happen when I first got Savvy. I had just installed a roto start backplate and all was well for untill at started to slip, then eventually not bite at all. Turns out I was too generous on greasing the roto plate gears and the grease made it's way to the one-way bearing. You may not have installed a roto plate but if your backplate seal leaks any, you might want to thuroughly clean out the crank case with nitro cleaner and clean all the parts associated with that dis-assembly. Make sure that you clean and WIPE DRY the one-way bearing and the bearing race it fits in. I used Q-tips for the bearing race. This gets alot of hidden trapped sludge the motor creates over time. If you DO HAVE a roto backplate, clean it's parts also leaving no grease. I was told that a one-way bearing can last the life of the motor but will act up when it gets accessive fuel oils or lubricants on it's surfaces. Also check for any tiny rips in the o-ring that seals the crank case and replace it if damaged. If no o-ring is presant, then use some high temp silicon sealant around the crank case cover where an o-ring should be. The sealant should also be nitro-methane compliant. If the o-ring is ok, then re-assemble the crank case backplate by tightening the bolts using blue thread lock in a star pattern for a good seal. Do the same threadlock and bolt up for the roto backplate. You should be good to go. I hope this helps.
 
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where does the o-ring go? is it sealing the plastic backplate case from the outside or does it seal around the shaft that the one way bearing goes on?
 
Ok. To be sure, What motor are you running? I'm reffering to a bigblock nitro star k4.6 which is the same as a 4.1 and a 25 in this case. But I'm not 100% sure, so please don't quote me no this. On my 4.6, there's NO 0-ring for the roto start backplate. after you remove the roto start, you now can see and remove the one-way bearing. The four bolts you now can see are securing the rear crank case cover plate. I don't have the manual in front of me for the actual part name, but hopefully you can easily see what I'm reffering to. Remove the four bolts and gently pull the this cover plate half way out and look for a seal of some kind. My 4.6 has a large yet very thin ring in place around the curcumference of the inner plate. The "plastic backplate doesn't require an o-ring. keep me posted.
 
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yeah i have the 4.1. i'm thinking that you are saying that the seal should be around the shaft that the one-way bearing is on. i'm looking in the manual and there is a seal between the backplate and the engine, but i'm not sure if this is the one you are talking about. It's part # 1425. I don't know how this seal could have moved because I have never taken the metal backplate off. I also think that fuel could be getting into that case when if i spill it and it goes in where the two halves meet.
 
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Actually, everything sounds fine at this point. I wasn't indicating any seal around the any shaft. The seal between the metal backplate IS the one I was reffering to. In my first post, I suggested that this metal backplate be removed when cleanning out the crank case. With the metal plate off, you'll be able to see the rest of the one-way assembly which is only one remaining area you'll want to clean. Use eye protection and spray out this whole area with nitro cleanner as I suggested in my first post. I also had suggested as a pre-caution, to check if the seal at the metal plate because it's always possible that it was not installed properly at the factory. It's most likely ok but, to actually look to verify that it's there, and in good shape, is to know for sure, right? I've heard of many accounts of engines that are not in thier best condition due to a half-a$$ assembly that got past the manufactures quality control dept. Things like: Loose metal fragments in the engine block, no locktight where locktight was needed, Loose screws, missing seals and/or o-rings, ect. This is not being said to alarm you but, sh!t happens as you will learn with any purchase in this hobby. If and when you deside to upgrade your motor at some point, It is recommended by many that you do an exploritory inspection inside your new motor JUST TO BE SURE that it was assembled properly with no debris inside it. So... After you know the seal is cool, go ahead and bolt her back up as I explained in my first post if you've already got the cleanning out of the way. Get her back in the truck and fire her up.
 
OK i took the engine out and took the plastic backplate off. and when i did i noticed that the seal on the exhaust was broken a little bight and sure enough the plastic set up and the one way bearing were soaking in oil. so i am assuming that the oil is coming from the exhaust and leaking down into the one way bearing, not coming from the backplate. I will try to fix up that seal until i get some parts.
 
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Good man, Speedster. I think you've got it! This was my point regarding the process of discovery. The things you can find along the way of an inspection never supprises me. That leaky exhaust seal can really cause tuning issues when trying to tune. With poor or no presure supplied by the pipe's return line, you can't get a propper fuel presure to tune correctly. Spray Nitro cleanner on the inside of your pipe,and header. Also spraying the whole outside of your motor is a good idea at this point. Again, I would still follow the path I indicated in earlier posts, but thats up to you. Good Luck.
 
If the one way bearing is slipping does the roto start just spin but flywheel does not? Ive got a K4.6 only 2 months old and this is happening. But on inspection everything works fine turning by hand? Also it looks like one way bearing fits inside pullstart shaft holder is this right?
 
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quite often, the OWB will work, when turning by hand, but fail under the torque of the rotostart...

so yes, that is what is happening...
 
Yes. kOmODo67 is correct. The one-way bearing and the race it turns in need to be clean and dry as possible to function properly. Overspilling fuel, leaky silicon exhaust seal, over lubricated roto backplate gears, or a damaged seal on the aluminum crank case cover can all play a part in a one-way bearing to slip.
 
i had this problem this afternoon, a temporary fix if you are in a pinch is to drop a little nitro fuel onto the bearing. Fuel contains oil which causes the bearing to slip if left or has come from the leaky exhaust, but the solvents in the fuel break any residue down for a short amount of time, enough to get a OWB to grip and start an engine.

this is not a solution to the slipping problem but can help, OWB should be degreased and cleaned on occasion, I have been lucky and just give it a quick clean if i have the starter of the back plate.
 
Yea... With the one-way, It's rarely a matter of replacement, it's always a matter of maitainance. To it's benifit, The OWB is supposed to be a lifetime part. Most of us out here will experience this slippage at some point,. it's just a matter of when. To insure it's lifespan, just get in there and clean it properly. Right when it starts to act up. It may last you for the life of the engine. Relentless attempts to getting an engine started under slipping conditions can quickly lead to premature ware on the OWB and it's race. There's even the chance of fracturing the OWB if poor starting conditions continue. This includes the resistance experienced from a near flooded or flooded engine.
 
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mine actually cracked a while ago. i think that they are worth around $35 Canadian so it's pricey.
 
yeah, i just recently got the problem with the one OWB and the slipping. I don't why it cracked, could have been from me flooding it, and it being a faulty part. Assuming that it is meant to be a engine life part i think it was faulty.
 
Sounds reasonable. I can't think of anything that would crack it either. HPI sould spring for that one.
 
I have actually cracked one as well...not sure why, but that's what caused mine to slip...
 
That could be anyone's guess but, I tend to lean on the theroy that has been discussed throughout this thread. "The infiltration of unwanted oils" can allow the OWB to slip and whip up enough chater-speed and over power the OWB's design limits, thus cracking it, in it's tendantcy to grip the OWB's outer race. Or not.lol
 
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Anyone know where to get hardened bevel gears part number - 86030 (but hardened) my truck strips the standard ones pretty quick!
Truck:-
K4.6 running 49 tooth spur with 17 tooth race bell and 3 speed tranny!
Fast as **** off a shovel when running right!
 
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