Mbtension Main bearing hydraulic change procedure

7/30/2019 Mbtension Main bearing hydraulic change procedure

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Page 1 of 10 h:mbtension new bearings.docT.Standish 9/29/04

Preliminary Instructions

Main Bearing Change Out ProcedureNote: this is for the new style main bearings (x2003091 and x2003092)

Detensioning1. Rotate crank so that counterweights are up and will not be in the way of main bearing

removal

2. Apply tensioners using tensioner cradle

3. Run both tensioners all the way down, and then back off ½ turn so the tensioners will

not bind when tension is released on studs4. Apply jumper hose to tensioners




5. Apply hydraulic pump hose to tensioner jumper hose

6. Apply hydraulic pump hose and 110 psi air to pump

Note: If the tensioners are not fully collapsed, seat on mains, make sure needle valve is

open, and turn down using ½” allen wrench (back off ½ turn when finished)




7. Close pump needle valve

8. Turn pump on until it reaches 19,000 psi, and then turn off




9. Use tommy bar to loosen nuts at least ½ turn

10. Open pump needed valve to remove pressure11. Remove hoses

12. Remove tensioners using tensioner cradle13. Remove main bearing cap nuts

Cap Dropping

1. Apply cap lifting bracket to bottom of main bearing cap




2. Apply cap-lifting device onto crankcase. Adjustments may be necessary to align

fixture to line up with cap bracket. Tighten fixture down to case. Fixture isaluminum, so do not overtighten.

3. Raise device to put pressure on the bottom of main bearing cap




4. Remove crossbolts from both sides of cap

5. Lower cap by loosening fixture screw.




Note: Don’t lower past rounded end of fixture!

Bearing removal1. Remove lower bearing for inspection

2. Apply upper bearing sweep tool (40080603) into oil hole of crank (may have to rotatecrank to apply)




3. Rotate crank counterclockwise (facing rear end) to sweep out upper bearing for

inspection (counterclockwise because there is a tang in the bearing)

Bearing application1. Apply a light film of oil to upper bearing

2. Apply upper bearing by hand aligning tang on bearing with tang slot on main3. Apply oil to lower bearing

4. Apply lower bearing aligning tang on bearing with tang slot on cap

Cap Lifting

1. Make sure there is no debris on cap/ case mating surfaces




2. Raise main bearing cap using cap-lifting device, make sure cap is aligned with dowel pin. Some wiggling may be needed to align properly.

3. Make sure cap is seated against case4. Lubricate threads, heads, and washers of crossbolts with threadtex grease and apply

5. Pre-torque right side bolt to 373 N⋅m (275-ft. lbs.)

6. Pre-torque left side bolt to 373 N⋅m (275-ft. lbs.)

7. Remove cap-lifting device

Tensioning

1. Make sure main bearing studs are tight, if not, torque to 203 N⋅m (150-ft. lbs.)

2. Apply and seat main bearing nuts using tommy bar, make sure drive holes are facing

out3. Apply tensioners using tensioner cradle

4. Run both tensioners all the way down and make sure rams are compressed. Note: if rams are extended too far, the seal will blow out.

5. Take out ultrasonic bolt gage6. Clean bottom of stud7. Apply couplant to transducer

8. Apply transducer to bottom of stud and take initial bolt length readings withultrasonic bolt gage




9. Apply jumper hose to tensioners

10. Apply pump hose to tensioner jumper hose11. Close pump needle valve12. Turn pump on until it reaches 19,500 psi, and then turn off, this correlates to a load of

267,000 lbs.13. Use tommy bar to tighten nuts14. Open pump needed valve to remove pressure

15. Repeat steps 8 – 11 one more time16. Take final bolt stretch readings using ultrasonic bolt gage

17. Final stretch to be 0.043” to 0.0505”18. Remove hoses19. Remove tensioners using tensioner cradle

20. Torque right side crossbolt to 1491 N⋅m (1100-ft. lbs.)

21. Torque left side crossbolt to 1491 N⋅m (1100-ft. lbs.)

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Mbtension Main bearing hydraulic change procedure