So I rebuilt my motor for my 2004 LS430.

After rebuilding, I noticed a ticking sound, that makes the car sound like a diesel engine that's coming from the RH cam gear area.

After searching extensively on the forums, I figured it could be cam gears not aligned due to missing service bolt: https://www.clublexus.com/forums/ls-...Q9AAgfUuPIsF8o

However, after taking it apart, I'm looking at my cam gear right now, and I think that the service bolt was simply just never removed? Is the silver bolt on the cam gear in the attached pictures the "service bolt"?

 

Looks like it. Remove it a see if the split gear springs apart. Leaving it in like that luckily doesn't cause damage. The timing remains correct but the purpose of the spring-loaded split gear is so there is no backlash between it and the other cam gear. Backlash causes the noise you hear now.

 

Yes please remove the bolt. Like 911 said it's put there to make sure the can doesn't move out of alignment when removing them.

 

Okay I'll give it a try!

Do you think leaving it in could be whats causing the backlash noise?

 

Yes, if the bolt is long enough to go through both halves of the split gear. I think the length of the service bolt is 10mm. If you look at your close-up pic you can see how the gear is actually 2 pieces that are spring loaded. The bolt holds the spring under tension and locks the gear halves together.

 

Just another confirmation here.

Yes that "service" bolt prevents the spring loaded scissor gear from losing tension when the camshaft is removed. The scissor gear is tensioned so it will take up the backlash (which creates noise) against the other cam gear, remove the bolt and your noise will be gone.

This video covers the gears probably more than you wanted to know.

 

On most Toyota/Lexus engines I've worked on the service bolt will collide with the cylinder head causing serious damage. I think you got lucky.

 

That's why the service manual specifies a certain length bolt.

 

The length is specified for the threaded portion so it protrudes far enough into the other scissor gear to stop it from untensioning, the bolt head has nothing to do with it.

 

Update: It worked, removing the bolt and the diesel engine noise is gone!