Broken Primary Timing Chain Pivot Pin

[RED09GT]

I found the source of why my motor is a complete dog. I never even gave any thought to these or knew that there was an upgrade available.


Has anyone sucessfully removed one of these? . Luckily, I didn't have piston to valve contact and I would like to avoid tearing the motor right down if I can help it. Can this be done? I saw a jig that used to be available but I can't find it for sale anywhere online.

 

[thump_rrr]

There is no stress on the remaining piece. It should come out easily with a left hand drill bit and an extractor.
I would insert a small piece of vinyl or rubber tubing into the hole to center a drill bit and drill a pilot hole for the left hand drill bit. As soon as you start drilling with the left hand bit it should start to back out on it’s own unless some thread locking agent was used.

ETA Cobra Engineering sells the drill plate with drill bit and tap to upgrade to 8mm.
It doesn’t mention the 3 valve but I’m sure others have done it before.
http://www.cobraengineering.net/drill fixture.html

 

[RED09GT]

Thanks for that, I'll definitely upgrade to the stronger pins and see if I can still get that plate as the holes look to be in the correct spots.
Found a piece of vacuum tubing that fits inside the hole to guide the drill.

 

[fdjizm]

So that broke and you got less came timing or too much etc..? causing the engine to run crappy?

 

[RED09GT]

It basically took the tension off the timing chain so it would be better described as having "erratic" cam timing on that side of the engine.

When I rotated the motor by hand and left it in some spots, the valvesprings would cause the phaser to rock backwards while the other side sat still. I shudder to think of what was happening with 15 lbs of boost and 5500+ rpms.

I'll need to grab a borescope and check the pistons for PTV contact.

 

[thump_rrr]

It basically took the tension off the timing chain so it would be better described as having "erratic" cam timing on that side of the engine.

When I rotated the motor by hand and left it in some spots, the valvesprings would cause the phaser to rock backwards while the other side sat still. I shudder to think of what was happening with 15 lbs of boost and 5500+ rpms.

I'll need to grab a borescope and check the pistons for PTV contact.

I’ve been running 13-14 psi 543RWHP for the last 10 years on the stock bottom end.
My 5.0L JDM stroker short block has been sitting on my engine stand for the last 5 years.
That looks like another upgrade I need to add to the list.

 

[RED09GT]

Got the broken end out of the block. That actually went well.

 

[thump_rrr]

Got the broken end out of the block. That actually went well.

It usually does when there’s no stress on the fastener.

 

[RED09GT]

John at Accufab told me that it takes a fair bit to break the stock one-even though they sell a better piece.
I'm still upgrading.

 

[sportinawoody]

Mine was broken also upon tear down. I bought the cobra chromemoly pins and had TKM do the drilling. Make sure you order the 8mm and not the 9mm pins as 3v arms won’t fit. Power isn’t usually the reason these break, 2 steps and bouncing of the limiter generally breaks these and mine were 31k miles since replaced with new oem ones. Won’t happen again to me.

 

[RED09GT]

Got the new ones in. I went hillbilly style and didn't use a jig, drilled it out 1/64 at a time and very little pressure. I dipped the bit in grease to catch the cuttings and things went well. As for why it failed, who knows. I can't remember for sure but I am wondering if I possibly torqued the pins to 89 inch pounds, which is too much for an M6 fastener. I also had the tensioner arms switched around as well. I'll chalk it up to a learning experience.

 

[RED09GT]

Car is back together and the first datalog looks promising. It now wants to keep pulling up top instead of getting noisy and hesitating after 5000 rpms. What a difference a small part can make!
I tried a datalog to 6500 rpm but actually went up close to 7000 due to it getting up there quicker than I was ready for.