crankshaft play.

i have a 89 mustang gt, 5.0 302. i thought my flywheel was wore cause i had starter problems. but i checked  into it and the starter and flywheel was fine. come to find out my crankshaft had play and was moving my flywheel..but the thrush bearings are fine. and all bearings is ok. but i cant find what caused the crankshaft to have play and let it move..only thing i saw was that the crankshaft had been worn down by the thrush bearing on the middle main cap..has anybody had this happen are have more info on what could cause this to happen..the motor had about 15.000 to 40.000 miles just guessing, since it was rebuilt. but me and my dad thought that the thrush bearings should have kept it from moving, and if anything let it move would be the thrush bearings being wore down or wore out..and answers would help me figure out this problem..i never heard of this till it happen to me..its a very odd thing to happen...which it messed up my crankshaft and block..there not fixable...but any help would be much thankfull..  

Well I am not sure I gleaned all your issues there Shig but it seems like you had thrust bearing failure. Thats thrust with a "T" not thrush. So named because it takes the forward and reverse motion(thrust pressure) of the crank, which should be small(clearances I mean). Causes for failure could be a bent crank, excessive clutch pressure, improper throwout bearing adjustment, a bad torque convertor, particles in the oil or just excessive heat. Every time you push on the clutch you push against the thrust bearing(so dont ride the clutch). Normally these clearances are in the range of about .003 or so. When you get enough movement to move your flywheel away from the starter your wayyyyyy beyond what the clearances should be and damage has already occured. You will need a new crank and have the block checked also and toss it if the bearing wore thru.  

yes your correct..sorry i have been working since 5 am this morningg and its 2 am..but yes the thrust bearing...and its a 5 speed car..the crankshaft is bad and it got the block..not really bad. but enough to were i wouldnt use it cause under pressure it could fail..but the thrust bearings is perfect. nothing wrong with them. i understand what your saying. and its just the way it happened, to me and my dad we dont understand it.ive took some pics. and that would let you understand more but i have to upload them to my computer. the crank wore down on the back side of the the main were the thrust bearings are.. as if the thrust bearing is what wore the crank down..and the crank wore a groove in the block above the thrust bearing..odd way of happening..but thanks for responding to me..i guess just with combined clutch pressure and heat from being caught in traffic combined caused it while i couldnt see it happening..but once again thanks alot...shig  

Well, bizarre things happen I guess. I had to go look at a short block to see how that could happen and its a mystery to me. Are you sure the thrust bearing was installed correctly on the right main ?  Really weird I dont know, the crank has a thrust bearing surface on it, it would have to wear thru the bearing first from what I can tell. Well anyway it sounds like you have nothing but paper weights left there. I would suggest a new shortblock,,,, and check the whole clutch, throwout bearing, pilot bearing and mating surface for problems. Good luck there Shig.  

Yes..thats what is odd about it..is the thrust bearings are fine..and were installed in the right place. i talked to a guy at a machine shop that i know, and he says he thinks it was the clutch, putting constant pressure on the crankshaft, pushing it forward. he said it could be caused by the throwout bearing being out of adjustment..i didnt know it could be out..im going back the end of this week to were the car is..and ill check out the transmisson, and clutch. the block is fixable,BUT i aint chancing it with it being the very middle main cap. and the one that holds the thrust bearings. ive got another complete motor that just needs a re-ring job. for 250 dollars..from oil pan up to the top intake, wiring harness,and even the shorty headers still on it..not a bad deal if ya ask me lol..long as its good when i get inside of it..thats the question to be..but i really do thank you for your time. and if i find out anything else ill let ya know, thanks alot mechanicalguy48  

i have also seen crank thrust failures on engines with clutches out of adjustment... with drivers who ride the clutch pedal...

there have been a few instances of thrust bearing failure do to improper crank finish on the thrust faces...   when they grind the crank main journals ... sometimes they bump the thrust surface with an undressed side of the crank grinding wheel..  makes it too rough... wears right through the thrust bearing...

there are also several new designs of thrust bearing faces... instead of just slots... they have a wave shape to them...  so the oil from the bearing surface is piled up like water skiing ..  builds up a layer of lube for the thrust face to be supported on..

there are also different qualitys of bearings...   steel backed aluminum...  sintered brass bearings.. and trimetal...  steel, copper/brass alloy  with thin layer of babbit...  the tri metal bearings are usually the best...


you did not say exactly which model car it's in.. but some cable operated clutches really need the replacement adjustable quadrant that fits on the clutch pedal...   ditching the factory automatic adjustment version...  

if you would have read the very top...i said its a 89 mustang gt 5.0 high output 302...5 speed.. and a hatchback... i might have left that out but its not in need...and yeah i have figured out only thing that could have happened was i had a bad crankshaft, and the thrust bearing wore against the crank wearing the crankshaft down till it over lapped the thurst bearing and ate into the block...so i agree with your idea about a bad crankshaft...  

i had the block checked..there gonna line bore the block, for $110. clean it for 60, 35 for replacing the cam bearings, and 40 to hone the cyclinders..total comes to around 250...then buying another crankshaft, and rebuilding the full motor...plus im gonna replace all the clutch parts, its already got a aftermarket clutch cable and so on..but this time ill keep a closer eye on things happening to the motor as i go along...but thanks for everybodys time and effort..just giving yall a update on whats going on with my mustang...  

hello there my name is vic.i have the similiar problem as the gentleman with the crankshaft i think.i have 94 5.0 302 mustang that ive been slowly upgrading.but it seems that everytime i do something goes wrong.2 get 2 the point,had 2 replace the clutch so i did,but didnt get the flywheel turn (didnt know i need it)so i installed the new clutch and rest of the components.test drove it starting feeling some rumble or vibration from the front.end up taking the trans out again checking the trans found it need it a output shaft bushing so i replace it.thinking that it waz the trans output shaft that waz worn out.so the point of my question is this after this long story,is how much of play does the flywheel has whn u push and pull on it.or how can i chk my crankshaft bearing if got loose and cousing the crankshaft 2 go in and out.