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Push rod SB for 912/914- Collar Cap Nut Torque

  • james porter
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1 week 6 days ago #17511 by james porter
james porter created the topic: Push rod SB for 912/914- Collar Cap Nut Torque
The 912/914 push rod replacement SB mentions loosening the M8 collar cap nut (if necessary) to facilitate the removal of the rocker arm shaft. It also cautions against loosening the M8 collar nut (which is unnecessary for the removal of the rocker shaft).
The SB says to tighten the loosened nut IAW the heavy maintenance or other SI's.
The Service Instruction (change in tightening torque procedures) specifically forbids tightening one nut or one cylinder. It seems that you have to loosen all nuts and go through the process for all the nuts on that side of the engine.
Is this a correct understanding and interpretation?
If not, what would be the correct procedure to restore the correct torque to the collar cap nut if it is required to be loosened to facilitate the removal of the rocker arm shaft?
The previous edition of the Illustrated Parts Catalog shows the torque on that nut to be 22 lb.ft., but again the newest SI changes the procedure.
I am interested in any input from anyone preforming the procedure under the SB.

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1 week 6 days ago - 1 week 6 days ago #17512 by Rob Seaton
Rob Seaton replied the topic: Push rod SB for 912/914- Collar Cap Nut Torque
99% of the affected engines were manufactured this past year. All of those engines have the fine-thread cylinder studs with the thin nuts, so removing the nut is not necessary as the rocker arm shaft will glide right past this thin nut.

In the RARE situation of a recently overhauled or repaired engine that is affected you only have to torque the one nut (as per SI-912-023)
Tighten to 10Nm
Tighten to 30Nm
Losen 360 degrees
Tighten 10Nm plus 150 degrees

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Last Edit: 1 week 6 days ago by Rob Seaton.
The following user(s) said Thank You: james porter

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1 week 5 days ago #17515 by james porter
james porter replied the topic: Push rod SB for 912/914- Collar Cap Nut Torque
Thanks for the reply. I was hoping that loosening the collar cap nut would not be required, but obviously wanted to be prepared for that possibility.
I couldn't find the reference in the SI you quoted.
The only reference I can find is in SI-914-026:
NOTE: The installation and tightening of a single cylinder head or any individual
cylinder head nut is not allowed. The entire procedure to torque both
cylinder heads together in one torque sequence must be performed.
Thanks again.

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