causes of bearing failure

[grumpyvette]

its well worth reading thru the links posted here carefully

http://www.nb-cofrisa.com/docs/web_fallos_ing.PDF

http://www.engineparts.com/publications/CL77-3-402.pdf

viewtopic.php?f=54&t=3519

http://www.stealth316.com/misc/clevite- ... ooving.pdf

http://kingbearings.com/files/Engine_Be ... erials.pdf

http://www.bracketracer.com/engine/mains/mains.htm

viewtopic.php?f=54&t=120&p=150#p150

http://www.circletrack.com/enginetech/c ... ce_basics/

http://www.thirskauto.net/BearingPics.html

http://engineparts.com/techbulletins/CL77-1-205R.pdf

http://www.bobistheoilguy.com/bearingwe ... alysis.htm




http://www.mahleclevite.com/publications/EB-40-07.pdf

Ive generally found the H-series bearings are the best choice

one factor to keep in mind is that rods typically have a side that rides against its matched companion and a side thats BEVELED for clearance on the crank journals radias EXAMPLE



notice the top rods non-beveled side that faces the matching rod is up, but on the lower rod the the beveled side that faces the crank counter weight is up on the lower rod


failure to clean out the oil passages in the block and crank journal cross feed oil holes, resulted in trapped debris being flushed out and scoring the bearings during the test fit process in these bearings, an easily avoided but very common screw-up after a cam or bearing fails and your forced to do a ring, cam,lifter, and bearing replacement
just keep in mind that you'll need to very carefully blend and smooth and carefully clean,the edges of the beveled area where the oil port feeds the bearing surface with some 600 grit sand paper so the oil flows well and theres no edges to cause bearing wear issues or crud left from the process that would get embedded in the bearings.



watch this video
http://www.youtube.com/watch?feature=pl ... dEFGJqpCMY
http://www.enginebuildermag.com/Article ... o_bad.aspx
MORE USEFUL INFO

BE 100% SURE that the oil pump bolt or STUD doesn,t protrude past the inner main cap surface , because if it bears on the rear main bearing shell it will almost always result in a quickly failed rear bearing
MAJOR CAUSES OF PREMATURE BEARING FAILURE
Dirt ......................................... 45.4%
Misassembly .......................... 12.8%
Misalignment .......................... 12.6%
Insufficient Lubrication.............11.4%
Overloading .............................. 8.1%
Corrosion ................................ .3.7%
Improper Journal Finish ............ 3.2%
Other ....................................... .2.8%

in a properly set up block a pressurized oil film supports the cam and main bearings
you would most likely be amazed at the metallic crud a few high temp magnets , and shrapnel screens can trap and prevent from getting to your oil pump and bearings, or the amount of crud a decent oil filter traps once its passed thru the oil pump, especially if the oil filters equipped with a strong magnet, but changing your filter and oil on a frequent basis and assembling your engine with the correct clearances helps a great deal, any time you use a block on a new engine build youll need to remove all the oil passage plugs an rod out the oil passages with a rifle bore brush and a high pressure pressure cleaner and replace the gallery plugs, and cam bearings.
if you've had a cam wipe a lobe or a bearing fail its an EXCELLENT IDEA to replace the cam bearings and use a rifle bore brush to remove metallic crud from the blocks internal oil passages because theres an excellent chance they have trapped metallic crud in them



viewtopic.php?f=51&t=1458&p=3265&hilit=shrapnel#p3265

viewtopic.php?f=54&t=120&p=867&hilit=+magnets#p867

viewtopic.php?f=54&t=2187

viewtopic.php?f=54&t=2080

viewtopic.php?f=54&t=65

viewtopic.php?f=54&t=64


http://www.appliedindustrial.com/base.cfm?page_id=3549
from chevy high performance mag








Common Causes of Bearing Failures

There are many causes of bearing damage. It is not always easy to determine the exact cause, but most bearing failures can be attributed to one or more of the following major causes:

Foreign matter: One of the most common sources of trouble in bearings is wear and pitting caused by foreign particles. This could be in the form of dirt, abrasive grit, lint, dust, steel chips, etc.

Improper mounting: Bearings should be mounted with a press fit on the rotating ring. Generally, the shaft rotates and the inner ring is mounted with a press or interference fit.

1. Mounting bearings on shafts by applying blows or pressure to the outer race will usually cause denting (true brinell).
2. Loose shaft fit – rotation of the shaft within the inner ring can produce heat and small loose particles of metal that will eventually get into the bearing, causing wear.
3. Loose housing fit – damage similar to loose shaft fit.
4. Excessive tight fits – (shaft and housing) can cause rings to crack. Usually causes excessive internal preload because of the removal of internal clearance. Causes high operating temperature and premature failure.
5. Out of round housings – usually found in split housings where careful machining is necessary to obtain round housing. Causes localized overloading with abnormal wear on surfaces and retainer pockets. Early fatigue occurs in these areas.
6. Poor finish on the bearing seat – a coarse finish on the bearing seat will soon break down causing a loose fit condition, previously described.

Misalignment: A frequent source of trouble resulting in overheating and separator failure. Common causes are bent shafts, out-of-square shaft shoulders, out-of-square spacers, and out-of-square clamping nuts. Inspection of the raceways will show the ball track veering from one side to the other.

Vibration Brinell (False Brinell): Caused by the rapid movement of the balls in the raceway while the equipment is idle. Rolling elements quickly remove lubrication and, because there is not enough rotation of the bearing, fresh lubricant is not moved back into the spot. This means the bearing is sitting in one spot, devoid of lubrication, and the movement of the rolling elements wears away the metal. The indentations run axially across the races.

Electrical Damage (Fluting): When electric currents pass through a bearing, there is arcing and burning at the points between the races and the rolling elements where the current jumps the air gap. Pitting or cratering of a bearing is caused by relatively large charges of electricity.

A line of small burns along the line of contact of the rolling elements is caused by a low current constantly passing through the bearing. This fluting or grooving is formed on all parts as the current continues to pass through the bearing, and the contact points change as the bearing rotates. The steel melts in the affected zone. Electrical damage will cause early spalling and results in a noisy bearing which will have to be replaced.

Improper Lubrication: Lack of or improper lubrication generally causes overheating or excessive wear in the bearing. These conditions can result from insufficient lubrication, improper lubricants, complete absence of lubrication, or insufficient lubrication due to loss through leakage. Also to be considered is the breakdown of lubricants either by oxidation or exposure to atmospheric conditions.

Fatigue: Fatigue means the fatiguing of the metal in the components of the bearing. It is a result of stress reversals produced when rotating members create flexing of the metal. Fatigue develops due to the magnitude of the load and the number of times it is repeated. Actually, the rolling elements create a wave of metal in front of them as they roll. Thus, the metal in the components is alternately put in tension and then compression. This action eventually results in flaking of the metal.

Corrosion: The finely finished surfaces of ball and roller bearings are readily subject to corrosion by water, acids, and other agents. Corrosion is basically abrasive in nature and will account for excessive or abnormal wear in bearings. Common causes of corrosion include moisture, acid action, poor or broken down greases, poor wrappings, and condensation resulting from excessive temperature reversals.

Defective Sealing: This enables foreign material and contaminants to enter the bearing, causing wear.

High Temperatures: High temperatures frequently cause premature bearing failure, the nature of the failure being predicated on the temperature to which the bearing is raised and the grease with which it is lubricated. Mild temperature elevations may cause grease to bleed which reduces the efficiency of the lubricant. Under increasingly elevated temperature conditions, oxidation causes loss of lubricating elements and the formation of carbon. The carbon thus formed may lock or jam the bearing. High temperatures may also reduce the hardness of the metal causing early failure. High temperatures can cause loss of internal clearance and preloading results. Many bearing failures can be traced to dirt. Cleanliness is always a must.

Storage: Dampness (rust) - store bearings in a dry room.

[grumpyvette]

Eliminating The Low Oil Pressure Gremlin


This solution has been the most effective in solving a problem that seems to creep up for every engine builder everywhere.

By Roy Berndt

Whether you're a Production Engine Remanufacturer (PER) or a Custom Engine Builder (CER), this issue has shown up in your warranty or complaint area like the nasty gremlin that it is. So let's go on a journey and see what you think.

"Low Oil Pressure" is the frightening gremlin of which I speak! Here is the situation: your customer just got his vehicle back with your newly remanufactured engine. But wait: as he returns home, as far as he can tell there is either no more - possibly less - oil pressure than the old engine had. Or, perhaps they notice that dreaded hot idle oil light flicker, even though the engine meets the minimum pressure allowed by the OE.

What does the innocent consumer believe? Defective workmanship, trying to get away with something, taking short cuts - no matter what the reality is, they feel like you're taking advantage of them!

Even though every component was machined to exacting specifications and tolerances, this problem rises up and grabs you like a mad pit bull with a death grip on your throat (see Tom Hanks in the movie "Turner and Hooch"). In more instances than I like to hear about the engine is replaced with another and everything appears to be fine.

Once the engine in question is returned, all kinds of diagnostics then take place, from oil bleed testing to complete disassembly and re-measurement of all of the components. Oil pump and pick up testing is conducted. Cam bearing oil hole locations are examined, yet invariably, nothing stands out as being a problem.

The components from that engine may be put back into the system and never see each other again as a complete unit. Yet none of the components are ever identified as a problem for any other assembly.

So how do you explain the oil pressure gremlin? More often than not you can't, and you just move on to "it happened" and that is that.

I can't give you a foolproof solution but how about one that has been extremely helpful in eliminating the oil pressure gremlins from many an engine?

Before I give you that however, let's take a quick moment to talk about what happens at the OE level when an engine is assembled. There was a time when the words "select fit" was limited to import engine applications and it allowed them to install select fit engine bearings that were slightly larger and smaller in size so that the optimum minimum bearing clearance could be obtained on each individual crankshaft journal be it connecting rod or main bearing. Well that procedure exists in nearly every engine application being assembled worldwide today.

Regardless of how stringent the procedures and quality control are on the remanufacturing side, the use of select fit bearings is neither feasible, economically sound or even available in undersize bearings.

But rising up again, as if from the dead, is the undying entrepreneurial spirit of the "engine builder." What do I mean by that? It's no trick - and for many situations they're proving to be the perfect treat: main bearings that seem to completely eliminate the low oil pressure issue.

No, they are not some voodoo magic but they are a way to address and combat the possible low oil pressure issues described above. What exactly are they? They are main bearings in which the oil grove is terminated prior to getting to the parting line.

As you'll see in Figure 1, below two different types of grooved upper main bearing shells


the oil groove terminates before it gets to the bearing parting line. This style of main bearing has accounted for a 15 percent or more increase in hot idle oil pressure. So if you're looking to eliminate some of those unexplained low oil pressure gremlins contact your bearing manufacturer and ask about this style bearing and availability for the engine applications that you are building.



you can improve thrust bearing durability, if you GROOVE the edge of the bearing in the area marked in green as it provides extra lubrication to the bearing where its needed most(the rear support face) that resists the pressure from the clutch and or/torque converter

increasing the groove, from 180 deg to 270 deg, lowers bearing support, increases oil flow rates and tends to increase wear
A special note of thanks goes out to the engineering people of ProFormance Engines, Springfield, MO, and in particular Reggie Gray.


Influence of Grooved Main Bearings on Performance
http://www.enginebuildermag.com/Article ... mance.aspx

Manufacturers are frequently asked what difference grooving makes. Various forms of main bearing grooving have been used over the years.


It’s essential to understand that bearings depend on a film of oil to keep them separated from the shaft surface. This oil film is developed by shaft rotation. As the shaft rotates it pulls oil into the loaded area of the bearing and rides up on this film much like a tire hydroplaning on wet pavement.

Grooving in a bearing acts like tread in a tire to break up the oil film. While you want your tires to grip the road, you don’t want your bearings to grip the shaft, so grooving is bad for maintaining an oil film. The primary reason for having any grooving in a main bearing is to provide oil to the connecting rods. Without rod bearings to feed, a simple oil hole would be sufficient to lubricate a main bearing.

Many early engines used full grooved bearings and some even used multiple grooves. Those choices were based on what engineers knew at the time. As engine and bearing technology developed, the negative effect of grooving was recognized and bearing grooving was removed from modern lower main bearings. The result is in a thicker film of oil for the shaft to ride on.

This provides a greater safety margin and improved bearing life. Upper main shells, which see lower loads than the lowers, and hence don’t apply the same load to the oil film, have retained a groove to supply the connecting rods with oil.

In an effort to develop the best possible main bearing designs for high performance engines, manufacturers have investigated the effects of main bearing grooving on bearing performance. The graphs (Figure 1) illustrate that a simple 180° groove in the upper main shell is still the best overall design.

While a slightly shorter groove of 140° provides a marginal gain, most of the benefit is to the upper shell, which doesn’t need improvement. On the other hand, extending the groove into the lower half, even as little as 20° at each parting line (220° in total), takes away from upper bearing performance without providing any benefit to the lower half. It’s also interesting to note that as groove length increases so does horsepower loss and peak oil film pressure, which is transmitted directly to the bearing.

Notes: You will still find some full-grooved main sets offered for older engines where demand is low and the engineering cost to bring the sets to current standards is not warranted (bearings generally represent the technology of the time the engine was developed).





here your looking at the results of an engine pulled down after only a short time running and the resulting bearing damage, its rather obvious that there was a great deal of metallic crud left in the oil passages, or oil pan, or block that got flushed into the bearings and that the block needs to be line honed and/or crank should be checked for straitness, journal taper and surface finish and roundness as the wear seems to indicate both particulates in the oil and un-even wear on the bearing surfaces
I generally see this when someone failed to pull the oil passage plugs and use a high pressure washer and solvent to clean out the blocks internally and externally after a lifter or cam or bearing fails , and remember machine shops are NOT fool proof , they are supposed to clean blocks after machine work but occasionally fail to do it correctly