vtraudt

Cam sprocket bolt on driver side, outside (exhaust?) cam sheered off.
Not sure how the sprocket is held to the shaft:
- friction (cone)
- keyway

With the bolt sheered off and the seal cap (?) off, oil is pouring out.

Does broken bolt mean timing 'jumped', bent valves, etc.?
Or is there a chance I only need replace the cam (because of piece of bolt stuck in there) and redo the timing?

tester123

Wow! that's something! Possibly, couple options here:

(with my experience working on a 4.2 engine. It may vary considerably on 3.0)

1) The proper way is really to drill into the broken bolt and use an extractor to remove it completely and complete necessary repair / replace bolt with new one. If that is not possible and you want it done right, replace cam.

2) Not a good way but, you can get away with: IF you have considerable depth of threads left that could be used, you could technically use a smaller length bolt and repair it. I'd clean the threads thoroughly to remove all oil (brake cleaner) and use the shorter bolt with high-temp thread locker and tighten it good =not a lot. Idea behind this is that the bolt holds the cam sprocket to cam. Beyond that, the bolt has no other function AFAIK.

>>>Disclaimer
Bear in mind that I am sharing this completely unorthodox repair procedure here for exploration and NOT suggesting you do it. Now, Would I do it? Well, considering mileage, weighing the risk of part's location and its core function, I'd be comfortable doing it. Also, I'd put thread locker on cam sprocket as well and gently tap it in AFTER timing is set and install the said bolt.
<<<

Either way, all that oil on timing belt cannot be a good thing to begin with. So, consider changing the timing belt. If it is due, may want to consider doing a timing belt job and replace components such as water pump, idlers, belt tensioner and so on...

Others may suggest better options but that's what came to my mind.

jcman

How did you discover this or more like what happened first?

As far as I can remember the cam belt sprocket has four positioning pins that center into the cam ends, the bolt just holds it tight.

At this point do a TB service as mentioned and when the belt is off the sprocket should fall off so a easy out can be used as mentioned by tester123.

redbullgotwings

i dont know what the other end looks like but you can weld a bolt to it and try to get it out that way. Make sure you heat it up before you try to extract it, heat heat heat is your best friend. Also maybe a soak in kroil.

if you cant remove it i would but a new cam not drill.

If you get a new cam or take the cam out i suggest taking it somewhere to get it put back in. I messed mine up when i put it back in and i bent all my valves

jcman

The cam belt sprocket is held and locked by friction by the bolt.

tester123

Interesting. How is it possible to "weld" a bolt to the broken portion INSIDE the cam? I am curious (not being cocky here). Also, I have to disagree with heat being the friend here. Remember the are cam seals; they'd melt/warp and lose their ability to seal oil in.
IF the OP is planning to VC and CAM seals, yeah, torch it. Even then, not sure if it would help. ...Just sharing my thoughts...
Actually, I have to disagree with you on this. Drilling is the first thing I'd try. Drilling here doesn't mean to drill out entire bolt. Instead, you'd use start with about a inch or so pilot hole and expand it with next size bit UNTIL an extractor can be screwed in. The point of drilling is to use the extractor to pull the broken piece out.
I feel bad for the headache you've endured with bent valves etc. This happened to you because timing slipped. When working with CAMs/t-belt, proper locking tools are necessary to set the timing back in place BEFORE starting the engine. That's why I was suggesting OP to do the T-Belt job. Most likely (I hope not the case), he will find out that once T-belt is removed OR if the sprocket comes loose, all bets are off! There is a very high probability that timing will slip because the cams are under valve spring tension and slightest movement will cause the cam to turn to a more restful position = Timing gone.
I can tell you all of this from direct personal experience.

Further, all that oil on T-belt will definitely shorten the belt's life (if not already) and the OP is looking at a bent valve scenario in near future when the belt slips due to oil or worse, it snaps. Either case, instant bent valves are almost guaranteed.
I'd Strongly suggest replacing the T-belt and cleaning oil (brake cleaner is your best friend here) from everything before new belt goes on. At that point once the belt is off, replacing few maintenance parts as I mentioned before is simply a no-brainer because the same T-belt locking/setting timing procedures would have to be performed EVERY TIME the t-belt comes off.

tester123

^ this, myself as well. Oil loss / leak discovery?

jcman

Not sure if you or redbullgotwings had is happen on a 3.0, the VVT on this one is a whole different bird compared to any other C5 engine and around that bolt is a keyed ring in the sprocket to set with a castled tip special socket when doing a TB service

vtraudt

Does someone have the specs for the bolt?
diameter and thread, length?

(currently no access to car or bolt).

My plan is to use a (hardened tip) chisel and grind it down to exact OD of bolt thread, with "V" cut into sharp end to create 2 'teeth' that have a chance to bite into the bolt piece.
Then attempt to extract.

Don't think I can use a very long THING drill to get 'in there' and drill a suitable hole for an extractor.

Hope it might just be 'sitting' in there and may take little to turn back out.

Would then put new bolt on to secure cam sprocket/gear/pulley and run compression test.

Not sure if crank bolt is accessible to turn engine for leak down test.

Note: the car DROVE to final destination as far as i was told. So chances are belt/cam has NOT jumped (yet)!!!
All 'jumps' and bent valves I ever experienced resulted in engine NOT running.
But have not head 'one bank only' jump/bent.

tester123

Bolt Part No: N 103 072 01 (AM12x1,5x115) [AVK Engine]
I was thinking about the same when suggesting the drill option... Try the chisel as you described and let us know how it worked out. Perhaps, one of us might use the same trick next time we are stuck.
Perhaps, soaking it multiple times with PBlaster or similar might ease the pain a bit...
There is that 12 point Head Bolt (M18) on Vibration Damper/Serpentine belt pulley... you could turn it by that if accessible without removing much (try from bottom).

... Tick Tock...
Personally, I haven't experienced this (Thank GOD) but from reading others' experiences perhaps, I am a bit over cautious about this topic... YMMV.