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How should engine bearings feel?

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How should engine bearings feel?

Old 08-09-2022, 05:33 AM
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Default How should engine bearings feel?

I'd like to hear some opinions on how engine bearings generally should feel when theyre good and when they need replacing.

In particular i have heard that rear engine bearings (especially ceramic ones) should feel perfectly smooth, no doubts at all about it, when spun from the rear with a finger. Almost like there is zero friction in the bearing.

Is this true?

I have been hearing a metallic sort of hissing sound from my engine when running and upon inspection of the internals i find the rear bearing to be slightly sandy in feel. Its very slight and not catching at all. But its not absolutely perfect.

Keeping in mind that this engine is basically brand new and just finished breaking in recently, does this mean it needs replacing?

The front bearing did have an air leak and is being replaced. Again strange for such a new engine. Could this have been the noise?

Bottom line is... The ceramic rear bearing feels slightly less than perfectly smooth and the engine is making a sound that i would describe as bearing noise. Does this mean i should replace it, given that this bearing is still pretty new?

(The engine is a picco p3tt)
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Old 08-09-2022, 07:25 AM
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For sure, the rear engine bearing must be smooth, no grit or anything notchy. If there is grit in the bearing chances are there is damage to the crank and possibly the crank. If you are capable you need to do a full inspection. If you are not I would recommend either Adam Drake or AMR to inspect and diagnose your engine. Good luck.
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Old 08-09-2022, 07:40 AM
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Originally Posted by jpz_67 View Post
For sure, the rear engine bearing must be smooth, no grit or anything notchy. If there is grit in the bearing chances are there is damage to the crank and possibly the crank. If you are capable you need to do a full inspection. If you are not I would recommend either Adam Drake or AMR to inspect and diagnose your engine. Good luck.

During break-in the fuel you used didn't have enough oil lube. which caused poor break-in and damage to the engine bearings. Recommended oil lube is 14-18%
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Old 08-09-2022, 08:04 AM
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Originally Posted by 1995 Monster T View Post
During break-in the fuel you used didn't have enough oil lube. which caused poor break-in and damage to the engine bearings. Recommended oil lube is 14-18%
Although i cannot rule out the fact that break in on this engine may not have been at the most optimal fuel mixture due to the front bearing always leaking more than i would like to see from the factory, my fuel has 15% oil content and is marketed more towards reliability and engine longevity rather than outright performance.

Therefore if break in caused the rear bearing to be less than perfect and make noise, i would attribute it to the front bearing leaking during break in causing a slightly too lean mixture rather than my fuel oil content
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Old 08-09-2022, 08:24 AM
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Originally Posted by jpz_67 View Post
For sure, the rear engine bearing must be smooth, no grit or anything notchy. If there is grit in the bearing chances are there is damage to the crank and possibly the crank. If you are capable you need to do a full inspection. If you are not I would recommend either Adam Drake or AMR to inspect and diagnose your engine. Good luck.
i can provide some pictures of my engine's internals, i see nothing wrong with any of it and know roughly what to look for.

The crank has some rust around the rear but that is very common with this picco engine given that it lacks a DLC coated crankshaft.












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Old 08-09-2022, 08:32 AM
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If i flick the bearing round with my finger it makes noise and doesn't sound smooth. Again it doesn't feel that bad, but this is the first time i have ever felt an engine bearing. Other bearings (not engine bearings) do not sound like this so i assume this bearing is definitely bad and the cause of the noise i hear when the engine runs.
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Old 08-09-2022, 09:24 AM
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I have never seen a new engine in 30+ yrs. with bad bearing from the start.. I suggest you contact the manufacture and get new replacement bearings. The symptoms you describe are common in used engines
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Old 08-09-2022, 09:55 AM
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Originally Posted by 1995 Monster T View Post
I have never seen a new engine in 30+ yrs. with bad bearing from the start.. I suggest you contact the manufacture and get new replacement bearings. The symptoms you describe are common in used engines
That's one of the things that baffled me. Thats why i didn't bother to think about the leaky front bearing during break in... Plus somebody told me that its fine for it to come leaky as thats how their engine was... Obviously some leak is fine but last time i ran the engine when i heard the metallic sound, the engine was leaking alot more than i would say is healthy and it wouldn't hold a tune or idle.

I think I'll just get some TKO bearings for the engine as i really cannot be asked to go through customer support due to the nature of the product.

I assure you the engine was brand new. It still has incredibly tight pinch... Ive only just started being able to turn it over by hand!
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Old 08-09-2022, 10:49 AM
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No engine should leak in the front at all. If so, then it's time to replace the bearings. Bad front bearing can cause the engine to lean and have a bad idle. The inside bearing can stop the engine and cause damage.
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Old 08-09-2022, 11:30 AM
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Originally Posted by 1995 Monster T View Post
During break-in the fuel you used didn't have enough oil lube. which caused poor break-in and damage to the engine bearings. Recommended oil lube is 14-18%
Not my engine sir.
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Old 08-09-2022, 11:39 AM
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Max Rackstraw, I hate to say it but if that motor was broken in with that rust on it? That is your bearing damage. Little bits of rust would flaked off and would get in the rear bearing.
If it were me, this is what "I" would do. I make no claims but have been racing a long time and like to get my moneys worth.

Take the motor completely apart and clean everything.
Get a new set of bearings.
Completely clean off all the rust from the crank. Use a dremel with a fine wire wheel and some type of oil. Maybe the Mugen Seiki assembly lubricant, something that wont attack the silicone in the crank.
Put the engine back together completely clean, rust free, and with the new bearings.Use the assembly oil on everything during reassembly. I bet you will be fine. I have done this several times and the motors ran flawless for the lifespan of the motor, 8-10 gallons.

Good luck.
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Old 08-09-2022, 11:42 AM
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I would also advise in the future, after your done racing or driving. Empty the fuel tank and after run your engine. Especially with non dlc cranks. Its old practice but it works.
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Old 08-09-2022, 11:52 AM
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Originally Posted by jpz_67 View Post
Max Rackstraw, I hate to say it but if that motor was broken in with that rust on it? That is your bearing damage. Little bits of rust would flaked off and would get in the rear bearing.
If it were me, this is what "I" would do. I make no claims but have been racing a long time and like to get my moneys worth.

Take the motor completely apart and clean everything.
Get a new set of bearings.
Completely clean off all the rust from the crank. Use a dremel with a fine wire wheel and some type of oil. Maybe the Mugen Seiki assembly lubricant, something that wont attack the silicone in the crank.
Put the engine back together completely clean, rust free, and with the new bearings.Use the assembly oil on everything during reassembly. I bet you will be fine. I have done this several times and the motors ran flawless for the lifespan of the motor, 8-10 gallons.

Good luck.
Its not just me that has had this happen to this particular engine. Some other guy on the picco p3tt engine thread had a brand new one start giving him issues only to find it has really bad rust inside on the crank and rear bearing. I think it must be some issue with the picco p3tt.

I have always used after run oil and never stored the engine with fuel in the tank and lines (other than maybe once but not for very long).
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Old 08-09-2022, 11:54 AM
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Originally Posted by 1995 Monster T View Post
No engine should leak in the front at all. If so, then it's time to replace the bearings. Bad front bearing can cause the engine to lean and have a bad idle. The inside bearing can stop the engine and cause damage.
From now on thats going to be my opinion too. I'll keep an eye on front bearing leakages
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Old 08-09-2022, 12:56 PM
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Your bearing feels gritty because it's rusted. Whatever you are doing in terms of fuel, after run and storage needs to change.
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