Should I be concerned...

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.

Quotes source post: 9087923

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

Quotes source post: 9088122

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.

Quotes source post: 9090108

NO DOUBT! I am quite good with my clutch and know better than to do things like sit at a light with my foot on it. Never could have seen this coming. I changed the crank sensor months back because it (the engine) was shutting off when it was getting up to temperature, and during deceleration when I would step on the clutch to down shift. Well the crank sensor was not the problem, because it was still shutting off during deceleration and downshifting. Its pretty obvious now, that it was the crank movement causing the sensor issues. The engine is toast. I capitulate. If I did not love this car so much I would simply ditch-it, but I'm going to fix it and drive it until the wheels will not stay on, so I may-as-well get used to dropping in a replacement engine from time-to-time. Thanks Phil for the photo's. Yea, I am familiar with the thrust shims in this engine. I think most of us refer to them as a thrust bearing because that's the term we are most familiar with. Phil, I realize that I have to replace the engine any way that I slice this issue. What are your thoughts on my just driving it until it completely fails? Possible collateral damage or anything. The engine is running really strong and I have no other issues with it.

If the engine is torn down now before a failure exists the repair is straight forward... We can have the engine apart, this issue rectified and be testing our work in the same week.. The key is intervention right now. When the thrust shim completely fails you need a crank, carrier and thousands of other dollars worth of replacement parts.

Quotes source post: 9090347

PM'd you.

Segway to the OP's post concerning crank movement: http://toronto.kijiji.ca/c-cars-vehi...AdIdZ337704933 Local car in my area. Crank movement and vibration? Sounds like one or more crank bearing spacers failed, (if not other issues as well). There is a lesson to be learned here. Bought at auction where of course there is no such thing as a proper inspection let alone PPI allowed... The $12K price he paid should have set off the alarms right there. Now he wants someone else to take over his silly purchase decision so he can get ALL of his money back? The rebuild story ie. engine sent out - means they told him it was toast or he needed to cut a cheque for north of $12K. 2 year loss of license issue? Over .80 DUI? (Up here a 2 year sentence means DUI without the breath interlock installed). Sorry for his tale of woe but really, buyer beware on these cars at auctions. Probably thought it needed only a 'few' bucks in repairs.

Quotes source post: 9093915

I do not know about all auctions but the auto auction site I visit once in a while allows authorized people -- you can't just walk in off the street -- to visit a car of interest and even start the engine and take the car on a test drive. There's a 'test track' which consists of about a quarter mile straight with a u-turn at the end and a separate return lane. During the auction cars are driven by auction employees to the auction proper and the engines are left idling while the cars ahead are auctioned. While an car is being auctioned, I watch auto brokers walk around looking, touching, listening, even checking paint with a paint thickness gage of cars of interest in the line. Once a car is under auction no pays it any mind. It is as it doesn't exist but the auctioneer and his helpers spot the bidders and the price goes up until the car is sold. This auction yard is very professionally run and moves - well did before the 'crash' -- over 90K cars a year through. That is it sells 90K cars. The manager told me the facility processes up to 130K cars per year. Sincerely, Macster.

Quotes source post: 9095061

Not here. Cars for dealer auctions are driven across the floor and are provided with lean check and car proof print out. Other then opening hoods and doors and looking under car, starting it up, checking the air works, radios work and no check engine lights - that's about it. NO MECHANICAL CHECKS ALLOWED. (Defined as using hand tools to remove anything) There is an MVDA arbitration system for Ontario dealers if car was misrepresented in some way. (Does not apply to public) For public auctions: Usually two preview days, all auctions here provide Car Proof for each car. You can start the car and rev the engine but you CANNOT DRIVE THE CAR or even move it. On day of auction car is driven up by staff. The buyer of the car I linked has outsmarted himself. 996's as you well know are not cars to be bought in this way. Revving the engine even to a knowledgeable mechanic doesn't tell the whole story. Certainly someone buying a car in this way is really rolling the dice. He would have been better off buying from a dealer (with the mark up that entails) but he would have been getting a car with a safety, clean air test and NOW the public is protected by the MVDA act. (Can't remember the time frame / mileage conditions) I'm betting he bought this car at a certain public auction near him that I know about. Cars require a 'fit' certificate which does not attest to a car without IMS, AOS issues, crank issues or any other significant issues not affecting safety. You could buy a car with a wonky torque converter on a TIP model for example requiring a rebuild. Too bad. It is what it is. You buy a winter beater up here at public auctions - NOT 996's sold on consignment when a member of the public suspects his IMS is about to go or he found pieces of chain ramps in his oil filter so off he sends the car to hoodwink the unsuspecting. These cars can look so nice to most people not familiar with them and inside lay a hidden issue that could cost thousands and or including needing a rebuilt engine. The worst thing in the world is to bring along a friend who 'knows cars' to advise you on buying one of these cars in this way. Will your friend who knows cars pay for the 3.4L you may have to replace?? Um, not likely.