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Technical 1953 Chrysler 331 Hemi crankshaft Center Thrust Bearing problem.

Discussion in 'Traditional Hot Rods' started by ace high, Mar 4, 2018.

  1. ace high
    Joined: Dec 15, 2007
    Posts: 210

    ace high
    Member

    Pulled down my pan to chase a low oil pressure when hot issue. Stock pump with floating pickup tube appears in good shape with no galling. Rod bearings all look good. Main bearings show scoring, so I’m changing them. BUT, the center main thrust bearing has its rear thrust surface worn so thin that it peeled away. There is pressure against the rear of the crank pushing it forward. I’m running a Chevy 4 speed and a hydraulic throw-out bearing

    What the hell is going on ????
     

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  2. greybeard360
    Joined: Feb 28, 2008
    Posts: 1,502

    greybeard360
    Member

    Theory... Hydraulic t/o bearing keeps constant pressure in pressure plate just enough for crank to run against thrust surface.
    You ride the clutch.
    You use the clutch... A lot.

    Looking at the bearing closer, I would look at the radius on the crank journal. It may be starving that surface of the bearing.. hard to tell from that pic.

    Sent from my Moto G Play using The H.A.M.B. mobile app
     
    stillrunners likes this.
  3. ace high
    Joined: Dec 15, 2007
    Posts: 210

    ace high
    Member

    Has nothing to do with riding the clutch. There is so much pressure on the back end of the crank, that while I was changing the main bearings, I couldn't get the thrust bearing in. I had to pry against the front of the crank with a bar and pry the crank backward. The crank feels like it is "spring loaded".
     
  4. BJR
    Joined: Mar 11, 2005
    Posts: 6,457

    BJR
    Member

    Input shaft on trans is too long, pilot on end of trans input shaft too long, hydraulic TO bearing not fully releasing, TO bearing too thick and pushing on pressure plate fingers all the time.
     

  5. greybeard360
    Joined: Feb 28, 2008
    Posts: 1,502

    greybeard360
    Member

    Crack the bleeder on the throw out bearing and see if the pressure goes away. If not, loosen the trans bolts and let the trans back out a little, then check again. At least eliminate all of that.

    Sent from my Moto G Play using The H.A.M.B. mobile app
     
  6. ace high
    Joined: Dec 15, 2007
    Posts: 210

    ace high
    Member

    I'll give it a shot. While looking through the inspection hole in the lower bellhousing, I can confirm that the T/O bearing is TIGHT against the fingers of the pressure plate.
     
  7. DAHEMIKOTA
    Joined: Aug 12, 2006
    Posts: 119

    DAHEMIKOTA
    Member
    from Tenn

    I would loosen the trans mounting bolts on the bell housing and see if that frees up the crank. Some of the old Hemi's did not have the pilot hole in the crank drilled deep enough for a manual trans. I drilled a lot of them back in the old days. Some guys would just cut the trans input shaft off to provide clearance. If that is the problem , it may be a good thing to check the bearing on the trans input shaft. I have seen trans cases busted because of this. Some of the old six cylinders had the pilot bearing holes drilled right into the engine oil passage in the crank so the torque converter used with their "Hy-Drive " transmission could get oil. If one was to use those engines with a regular manual shift the clutch would get flooded with engine oil.
     

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