Would it be possible for an oil to be so slippery that roller lifters or roller rockers don't actually roll because there is not enough friction to make them, and so they just slide along with out turning? I have heard (although rarely) of problems where roller lifters didn't roll and wiped out cams. I suspect it would be a faulty lifter, but I just wonder if it's possible that the oil had something to do with it????
oil to slippery?
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very thick oil will do that
bruce
bruce
Bruce381, what do you consider "very thick oil"?
Yeah... 10W-40 will do that.
Urban myth.
It did happen but the problem was the design that didn't work well at very high RPM and oil was blamed.
It did happen but the problem was the design that didn't work well at very high RPM and oil was blamed.
This is one of the myths Harley Davidson used to tell people about using syn. oil. After HD started marketing their Syn 3 oil a few years ago, it suddenly was O.K. to use synthetic in Harleys. Some cams a lifters were wiped out when the TC first came out, but it was because of bad cam bearings and junk roller bearings in the roller lifters. This had nothing to do with oil that was too thick or because in was synthetic.
As far as the oil being too thick, HD's require A minimum of 10-40 and usually use 20-50.
As far as the oil being too thick, HD's require A minimum of 10-40 and usually use 20-50.
if the lube film so thick, and the oil so slick, and assuming the bearing was good, how could it possibly do any damage to the cam? If there was not enough friction to make a good roller turn, I don't see how it could be doing any contact damage to the cam.
Kestas
Staff member
This is actually a real problem in the bearing industry called "skidding". That's when a bearing is asked to go from zero to some high rpm rather instantaneously. The rollers skid upon startup. Repeated skidding can damage the metal. This problem is not related to the lubricant so much as the preload on the bearing.
To follow this analogy, this means that if the roller lifters start skidding, they don't have enough spring force to hold them down onto the cam surface.
To follow this analogy, this means that if the roller lifters start skidding, they don't have enough spring force to hold them down onto the cam surface.
Valve float.
skidding is usually evident under either high misalignment conditions that cause the rollers to not be perpendicular to the raceway, or under incorrect setting conditions like you mention...or when the cage is damaged. The real concern about high speed starts at loose settings is cage fatigue leading to cage damage, which will cause the rollers to skew causing skidding. The brief second a roller might skid at start-up is of little to no detriment to the life of a roller bearing.
Balderbaloney. That's like worrying about having too much money in Beverly Hills.
Correct and as I said a very thick oil WILL aggaravte this condition How thick? high vis >1,000 cst @ 40 something you would NEVER see in a PCMO BUT you can "skid" roller bearings.
bruce
Kestas
Staff member
I agree. I just can't see cam rollers experience skidding. There's just not enough acceleration or decceleration of the rollers.
Thanks, answered my question.
I've heard this same issue talked about with regards to roller cranks (in motorcycle engines).
It goes something like this: "Don't use a synthetic oil in a roller-crank engine because it is too slippery and the bearings don't roll, they slide and once they slide they get 'flat-spotted' (worn) and you'll ruin the bearings and the motor."
I agree with what DriveHard said: "If there was not enough friction to make a good roller turn, I don't see how it could be doing any contact damage to the cam."
It just sounds like nonsense.
--- Bror Jace
It goes something like this: "Don't use a synthetic oil in a roller-crank engine because it is too slippery and the bearings don't roll, they slide and once they slide they get 'flat-spotted' (worn) and you'll ruin the bearings and the motor."
I agree with what DriveHard said: "If there was not enough friction to make a good roller turn, I don't see how it could be doing any contact damage to the cam."
It just sounds like nonsense.
--- Bror Jace
No, It does not happen!!! It is a myth.It almost sounds like that old Harley myth about synthetic oil. Fast forward 10,15 years and wow Harley has a synthetic oil. Go figure.
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