Cam reinstall and timing

[romemmy]

Hi all,

Just wanted to verify a few things when reinstalling my cams here.. The manual is a little vague on some parts so I don't want to just assume..

Basically I have the cams in, I have the special tool installed holding the cams, and I've put the inlet vanos gear on loosely with the chain.. Since these engines don't use a locator pin for the gear, it's literally just the center bolt that maintains timing. So I just want to verify the steps..

1) set the crank at the 10deg position first?
2) install the chain tensioner
3) the gear should now be pretty static with the chain holding it
4) put the brand new central bolt in and do a full torque cycle (200deg on the final step)
5) release the central bolt and tighten to just 10Nm
6) move the crank back to TDC to remove any chain slack
7) fully torque the central bolt again
8) install the exhaust gear (making sure it's still tensioned)
9) fully tighten the exhaust central bolt, release and re tighten it fully.
10) rotate engine 360deg to make sure everything is good

I just listed that from memory, so let me know if I missed any steps. The crank position when timing still worries me a bit.. The 10Nm preload - does that allow the gear to move a little when shifting the crank to TDC?

Anyway, any comments (or maybe a link to an article) would be appreciated, else I'll go through the service manual again to verify my steps!

Thanks!

S.

[deansbimmer]

1) set the crank at the 10deg position first?
2) install the chain tensioner
3) the gear should now be pretty static with the chain holding it
4) put the brand new central bolt in and do a full torque cycle (200deg on the final step)
5) release the central bolt and tighten to just 10Nm
6) move the crank back to TDC to remove any chain slack
7) fully torque the central bolt again
8) install the exhaust gear (making sure it's still tensioned)
9) fully tighten the exhaust central bolt, release and re tighten it fully.
10) rotate engine 360deg to make sure everything is good

All good with these notes to add:

*The 10deg position is only for setting timing. Check timing at TDC.

4) This is an initial pre-stretch of the bolt and prepares it for the final torque hold.

4) The 10nm is enough to hold tension on the chain while sending to TDC. If there is already adequate or too much tension in the chain then the 10nm will allow slippage to the 'target' chain tension.

8) Yes. Remove the anti-chatter gear holder (or rear holding screw) to release the anti chatter gear disc before tightening the main bolt. That takes out any slop and helps with a more accurate set point.

10) Rotate engine several times. 360 degrees of crank rotation doesn't turn over the valvetrain completely. Rotating several times helps settle the cams and chains.

11) Be sure to perform the cam timing checks. You probably won't get it perfect the first time. You're allowed up to 1mm space between the cam fixture blocks and the head surface. Any more than that and you need to adjust. You also check bank 2 first with the cams upside down, then check bank 1. Follow the TIS instruction for this. You can get it perfect after a couple of attempts.

[romemmy]

Originally Posted by deansbimmer

1) set the crank at the 10deg position first?
2) install the chain tensioner
3) the gear should now be pretty static with the chain holding it
4) put the brand new central bolt in and do a full torque cycle (200deg on the final step)
5) release the central bolt and tighten to just 10Nm
6) move the crank back to TDC to remove any chain slack
7) fully torque the central bolt again
8) install the exhaust gear (making sure it's still tensioned)
9) fully tighten the exhaust central bolt, release and re tighten it fully.
10) rotate engine 360deg to make sure everything is good

All good with these notes to add:

*The 10deg position is only for setting timing. Check timing at TDC.

4) This is an initial pre-stretch of the bolt and prepares it for the final torque hold.

4) The 10nm is enough to hold tension on the chain while sending to TDC. If there is already adequate or too much tension in the chain then the 10nm will allow slippage to the 'target' chain tension.

8) Yes. Remove the anti-chatter gear holder (or rear holding screw) to release the anti chatter gear disc before tightening the main bolt. That takes out any slop and helps with a more accurate set point.

10) Rotate engine several times. 360 degrees of crank rotation doesn't turn over the valvetrain completely. Rotating several times helps settle the cams and chains.

11) Be sure to perform the cam timing checks. You probably won't get it perfect the first time. You're allowed up to 1mm space between the cam fixture blocks and the head surface. Any more than that and you need to adjust. You also check bank 2 first with the cams upside down, then check bank 1. Follow the TIS instruction for this. You can get it perfect after a couple of attempts.

Thanks Dean! Exactly what I was looking for

S.

[e92Mjunky]

how do the cams feel?