I cannot seem to find this issue occurring anyplace else in searches- The crankshaft in my 2001 C4 cab has quite a bit of horizontal play. I can see it move about a 16th of an inch inside the bell housing when pressing on the flywheel. This is causing a bit of a problem with my crank positioning sensor on deceleration (the engine dies when I step on the clutch). Decided to drop the tranny to check clutch and change my IMSB and RMS.

To much back and forth play in the crankshaft is giving me the creeps.... can that be repaired without a complete rebuild or engine replacement?

 

Did you remove the flywheel and try to move the crankshaft by hand to validate the play is in the crank and not the flywheel?

.0.0625" is a huge amount of play (21 times more than normal). I would be surprised if the engine is still running (it shouldn't be). I would validate those measurements with a good dial indicator on the crank before moving forward. And I wouldn't run the engine until you do so.

Normal radial play should be around .003" (less when there is oil pressure).

edit: Sorry to the OP, I re-read my reply and I totally misread your initial post. I had radial play in my mind for some reason and quoted you some measurements ...

And certainly as Jake points out below in this thread the axial play (parallel with crankshaft) is controlled by the thrust shims.

In either case, if your measurement of 0.0625" is accurate that play is far greater than factory specs, and what F6I sets their engines up at.

 

My reply: NO

 

Thanks for the quick reply. The engine runs fine, no oil leaks, RMS is bone dry, etc.. However, if I remove the flywheel, how does that change that I can see the crankshaft move inside the bell housing so much, when pushing on the flywheel from the other side. Even with the flywheel on should the crank move that much?

Am I missing something in understanding your suggestion?

TIA

 

The DMFW is a two piece part. It might be possible the ring gear or plate you can push on has separated from the other half. But that might be wishful thinking (not sure that is possible). I would still do it if it were my car.

If you have a spun crank bearing and anywhere near .06" of true crank play (more than half of the thickness of a crank bearing) ... no matter how you look at it you are looking at the cost of a replacement engine even if you tear it down to repair/replace the bearing housing, bearings, and replace the crankshaft.

 

Dual mass flywheels are two pieces. Sometimes movement of a failed or failing flywheel can be deceptive. That is why it is good to double check with the engine as bare as possible. Do you see the accessory drive pulley moving the same amount at the other end?

 

logray,
You type faster

 

Indeed I do!

 

Quick, general, thrust bearing tutorial partial copy below.

http://www.4secondsflat.com/Thrust_b..._failures.html

"Crankshaft Thrust Bearing Failure - Causes & Remedies
For years both transmission and engine rebuilders have struggled at times to determine the cause of crankshaft thrust bearing failures. In most instances, all of the facts concerning the situation are not revealed at the onset of the failure. This has led to each party blaming the other for the failure based only on hearsay or what some "expert" has termed the "cause". Some of those explanations have led to an argument, that ends up in litigation while the truth lingers uncovered in the background. This document is a group effort of combined information compiled by the Automotive Transmission Rebuilders Association (ATRA), the Automotive Engine Rebuilders Association (AERA), the Production Engine Rebuliders Association (PERA), the Automotive Service Association (ASA) and bearing manufacturers. This group of industry experts has assembled the following information to consider and offers solutions that may prevent a similar thrust bearing failure.

Background:
Although thrust bearings run on a thin film of oil, just like radial journal (connecting rod and main) bearings, they cannot support nearly as much load. While radial bearings can carry loads measured in thousands of pounds per square inch of projected bearing area, thrust bearings can only support loads of a few hundred pounds per square inch. Radial journal bearings develop their higher load capacity from the way the curved surfaces of the bearing and journal meet to form a wedge. Shaft rotation pulls oil into this wedge shaped area of the clearance space to create an oil film which actually supports the shaft. Thrust bearings typically consist of two flat mating surfaces with no natural wedge shape in the clearance space to promote the formation of an oil film to support the load.

Conventional thrust bearings are made by incorporating flanges, at the ends of a radial journal bearing. This provides ease in assembly and has been used successfully for many years. Either teardrop or through grooves on the flange, face and wedge shaped ramps at each parting line allow oil to enter between the shaft and bearing surfaces. However, the surface of the shaft, as well as the vast majority of bearing surfaces, are flat. This flatness makes it more difficult to create and maintain an oil film. As an example; if two gauge blocks have a thin film of oil on them, and are pressed together with a twisting action, the blocks will stick together. This is similar to what happens when a thrust load is applied to the end of a crankshaft and oil squeezes out from between the shaft and bearing surfaces. If that load is excessive, the oil film collapses and the surfaces want to stick together resulting in a wiping action and bearing failure. For this reason, many heavy-duty diesel engines use separate thrust washers with a contoured face to enable them to support higher thrust loads. These thrust washers either have multiple tapered ramps and relatively small flat pads, or they have curved surfaces that follow a sine-wave contour around their circumference.

Recent developments:

In the past few years some new automotive engine designs include the use of contoured thrust bearings to enable them to carry higher thrust loads imposed by some of the newer automatic transmissions. Because it’s not practical to incorporate contoured faces on one piece flanged thrust bearings, these new engine designs use either separate thrust washers or a flanged bearing which is a three piece assembly.

Cause of failure:

Aside from the obvious causes, such as dirt contamination and misassembly, there are only three common factors which generally cause thrust bearing failures. They are:

Poor crankshaft surface finish

Misalignment

Overloading

Surface finish:

Crankshaft thrust faces are difficult to grind because they are done using the side of the grinding wheel. Grinding marks left on the crankshaft face produce a visual swirl or sunburst pattern with scratches - sometimes crisscrossing - one another in a cross-hatch pattern similar to hone marks on a cylinder wall. If these grinding marks are not completely removed by polishing, they will remove the oil film from the surface of the thrust bearing much like multiple windshield wiper blades. A properly finished crankshaft thrust face should only have very fine polishing marks that go around the thrust surface in a circumferential pattern.

Alignment:

The grinding wheel side face must be dressed periodically to provide a clean, sharp cutting surface. A grinding wheel that does not cut cleanly may create hot spots on the work piece leading to a wavy, out-of-flat surface. The side of the wheel must also be dressed at exactly 90° to its outside diameter, to produce a thrust face that is square to the axis of the main bearing journal. The crankshaft grinding wheel must be fed into the thrust face very slowly and also allowed to "spark out" completely. The machinist should be very careful to only remove minimal stock for a "clean-up" of the crankshaft surface.

In most instances a remanufactured crankshaft does not require grinding of the thrust face(s), so the grinding wheel will not even contact them. Oversize thrust bearings do exist. Some main bearing sets are supplied only with an additional thickness thrust bearing. In most of those instances, additional stock removal from the crankshaft thrust face surface may be required. Crankshaft end float should be calculated and determined before grinding additional material from the thrust face.

Crankshaft grinding wheels are not specifically designed for use of the wheel side for metal removal. Grinding crankshaft thrust faces requires detailed attention during the procedure and repeated wheel dressings may be required. Maintaining sufficient coolant between the grinding wheel and thrust surface must be attained to prevent stone loading and "burn" spots on the thrust surface. All thrust surface grinding should end in a complete "spark out" before the grinding wheel is moved away from the area being ground. Following the above procedures with care should also maintain a thrust surface that is 90° to the crankshaft centerline.

When assembling thrust bearings:

Tighten main cap bolts to approximately 10 to 15 ft.lb. to seat bearings, then loosen.

Tap main cap toward rear of engine with a soft faced hammer.

Tighten main cap bolts, finger tight.

Using a bar, force the crankshaft as far forward in the block as possible to align the bearing rear thrust faces.

While holding shaft in forward position, tighten main cap bolts to 10 to 15 ft.lbs.

Complete tightening main cap bolts to specifications in 2 or 3 equal steps.

The above procedure should align the bearing thrust faces with the crankshaft to maximize the amount of bearing area in contact for load carrying.

Loading:

A number of factors may contribute to wear and overloading of a thrust bearing, such as:

1. Poor crankshaft surface finish.

2. Poor crankshaft surface geometry.

3. External overloading due to.

a) Excessive Torque converter pressure.

b) Improper throw out bearing adjustment.

c) Riding the clutch pedal.

d) Excessive rearward crankshaft load pressure due to a malfunctioning front mounted accessory drive.

Note: There are other, commonly-thought issues such as torque converter ballooning, the wrong flexplate bolts, the wrong torque converter, the pump gears being installed backward or the torque converter not installed completely. Although all of these problems will cause undo force on the crankshaft thrust surface, it will also cause the same undo force on the pump gears since all of these problems result in the pump gear pressing on the crankshaft via the torque converter. The result is serious pump damage, in a very short period of time (within minutes or hours).

Diagnosing the problem:

By the time a thrust bearing failure becomes evident, the parts have usually been so severely damaged that there is little if any evidence of the cause. The bearing is generally worn into the steel backing which has severely worn the crankshaft thrust face as well. So how do you tell what happened? Start by looking for the most obvious internal sources...."

 

I was afraid of that- the "thrust bearing". You pointed out exactly what was on my mind. Everything seems fine, no leaks etc. Kinda, like a IMSB failure without the engine getting grenaded.

Flywheel is off and the accessory drive pulley is moving quite a bit at the other end.

OK, I've got a major issue here... DAMN! CRAP! CRAP! CRAP!

Thanks Gents You've been a great help... very much appreciate it.

 

Check this out

3.4 engine for sale

 

WOOOOO! I am on it! THANKS A TON.

 

The M96 uses a pair of thrust shims to set longitudinal end play for the crankshaft... These shims have varying degrees of quality from the factory and some are soft. I have seen these fail and end up in the oil sump, literally falling out of the crank carrier.


I set these up at .0045 and have been using a professionally applied proprietary coating on them to reduce wear over time.


People that persist on their extended oil service intervals, use of M1 or like to sit at traffic lights with their foot on the clutch all create more wear for these shims.

If you have that much longitudinal end play in the crane, and you can see the pulley moving fore/ aft the issue is not the flywheel, the issue is these thrust shims.

So the M96 does not have a "thrust bearing"... It has a thrust deck on the crankshaft and utilizes a pair of shims to control longitudinal play.

 

Sorry to the OP, I re-read my reply and I totally misread your initial post. I had radial play in my mind for some reason and quoted you some measurements ...

And certainly as Jake points out above the axial play is controlled by the thrust shims.

In either case, if your measurement of 0.0625" is accurate that play is far greater than factory specs, and what F6I sets their engines up at.

 

Oh Great! Another "freaking" bearing/deck to worry about.