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Old 05-16-2014, 12:29 AM   #1
petsur
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Default LS3 Broken Rocker Stub

Anyone ever break a rocker stud? ?

I did. Tracking the car and lost power. Drove it 100 miles home as it sounded normal I thought it was fuel/spark related.

Just put a mild cam in the car which has 6000 mi on it and about 300 since the cam.

Did a compression check tonight and one cylinder was next to zero. Pulled the valve cover and a rocker was laying on it's side. I thought it would have been a broken spring, but nope, broken rocker stud.

Here's the real bitch, it broke probably 1/4 inch into the head so the top of the bolt is probably 1" long and I can't find the frigging thing. Spent an hour looking at the springs and underneath in case it fell out, but nothing.

It would make me crazy to repair the stud and put it together with a 1" screw in the oil pan, but there's no way it would fit past the push rods. Someone tell me to put it back together, it will be ok. Anyone ?? Thoughts??
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Old 05-16-2014, 08:05 AM   #2
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You could drain the oil and get a magnet extension to feed through the oil drain and see if it catches anything. Long shot but worth trying.

I am on the hunt myself for a valve spring lock. It popped off and I can find it either.
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Old 05-16-2014, 08:10 AM   #3
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You could drain the oil and get a magnet extension to feed through the oil drain and see if it catches anything. Long shot but worth trying. I am on the hunt myself for a valve spring lock. It popped off and I can find it either.
Yeah I'll drain the oil today and try what you said, but that side of the engine (passenger) seems to have a black hole under it. Dropped a socket from above and it was 2 weeks later when I found it. I hope the bolt is there.
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Old 05-16-2014, 08:11 AM   #4
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You might be on to something. I lost the lock on the passenger side too.
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Old 05-16-2014, 08:30 AM   #5
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When you did the compression check-that cylinder was "next to zero"?

, obviously both valves should be closed to get a reading on the compression gauge- why don't you have compression? Is it possible the valve got bent prior to the rocker arm failure?You should try a leak down test next-that would immediately show if either valve is bent.

The broken stud-or what remains of it is a big concern-but the compression check should be normal if all that has failed is the rocker arm.Not to mention just fixing the broken rocker stud is not addressing why it broke in the first place. Looks like you have a lot of work to do-that broken stud and nut HAS to be found, if it means the motor comes apart so be it.

It'll find its way out of the engine-one way or the other....

Last edited by Arclight; 05-16-2014 at 08:53 AM.
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Old 05-16-2014, 02:24 PM   #6
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When you did the compression check-that cylinder was "next to zero"? , obviously both valves should be closed to get a reading on the compression gauge- why don't you have compression? Is it possible the valve got bent prior to the rocker arm failure?You should try a leak down test next-that would immediately show if either valve is bent. The broken stud-or what remains of it is a big concern-but the compression check should be normal if all that has failed is the rocker arm.Not to mention just fixing the broken rocker stud is not addressing why it broke in the first place. Looks like you have a lot of work to do-that broken stud and nut HAS to be found, if it means the motor comes apart so be it. It'll find its way out of the engine-one way or the other....
Makes sense what you're saying. The guy that did the cam also did Comp's trunnion upgrade but did not use the new rocker bolts that come with the kit. He used the factory rocker bolts.
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Old 05-16-2014, 03:13 PM   #7
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Makes sense what you're saying. The guy that did the cam also did Comp's trunnion upgrade but did not use the new rocker bolts that come with the kit. He used the factory rocker bolts.
I was wondering if you had the trunnion upgrade, but the bolts looked to be the stock ones. I know for a fact that my comp cams trunnion kit, the shaft area came recesed for the allen type bolts. So basically those oem bolts either dont have enough threads tightening in the head casting or the other way around, and there's play or even worse, not the correct valve geometry. You tell me, but something tells me that whoever put it together for you is at fault.

Why wouldnt he use the provided bolts? I bet he stripped one or two of the allen heads and just decided to do what he did

Last edited by Pitufina; 05-16-2014 at 03:34 PM.
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Old 05-16-2014, 05:12 PM   #8
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That looks like an intake(?), if it was, since the intake valve didn't open, I would expect to see very low compression during a compression test.
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Old 05-16-2014, 05:35 PM   #9
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That looks like an intake(?), if it was, since the intake valve didn't open, I would expect to see very low compression during a compression test.
After thinking about it, I was thinking the same thing. Snapped off the easy out, ***.....
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Old 05-16-2014, 06:20 PM   #10
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That looks like an intake(?), if it was, since the intake valve didn't open, I would expect to see very low compression during a compression test.
Forget the compression test. Use a leak down tester. Basically the engine is rotated until both valves are closed. The spark plug is replaced by an air hose,using a regulated air supply- put 100psi of air into the cylinder-no leakage at all is not going to happen but 90%+ should not escape. If the intake is bent or has a damaged seat the air will escape through the intake tract and can be heard coming from the manifold,conversely if the exhaust valve has damage the air will leak through the exhaust manifold. Some leakage is to be expected in a cold engine with some escaping by the rings.

A compression test is a good fast way to compare cylinders but with a leak down-you KNOW what psi is going in- as well as coming out

IMO, you MUST find that broken stud- not to mention the fact that if it shattered,there is enough small debris floating around in the drive home-that might have been captured by the oil filter. Either way- that motor has to come apart- at least the top end. You also have to wonder if the lifter was damaged in anyway. Upgraded rocker arms are a must if you are doing track days-Jesel or T&D might be overkill-but they won't break. Not to mention establishing a maintenance schedule to check the seat pressure on your valve springs. Better to replace weak springs than dropping a valve.

Unfortunately, it will probably easier to get the broken stud out with the head removed on a work bench than over an open motor. Hopefully its not your DD.

Last edited by Arclight; 05-16-2014 at 06:23 PM.
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Old 05-16-2014, 07:27 PM   #11
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Quote:
Originally Posted by Arclight View Post
Forget the compression test. Use a leak down tester. Basically the engine is rotated until both valves are closed. The spark plug is replaced by an air hose,using a regulated air supply- put 100psi of air into the cylinder-no leakage at all is not going to happen but 90%+ should not escape. If the intake is bent or has a damaged seat the air will escape through the intake tract and can be heard coming from the manifold,conversely if the exhaust valve has damage the air will leak through the exhaust manifold. Some leakage is to be expected in a cold engine with some escaping by the rings. A compression test is a good fast way to compare cylinders but with a leak down-you KNOW what psi is going in- as well as coming out IMO, you MUST find that broken stud- not to mention the fact that if it shattered,there is enough small debris floating around in the drive home-that might have been captured by the oil filter. Either way- that motor has to come apart- at least the top end. You also have to wonder if the lifter was damaged in anyway. Upgraded rocker arms are a must if you are doing track days-Jesel or T&D might be overkill-but they won't break. Not to mention establishing a maintenance schedule to check the seat pressure on your valve springs. Better to replace weak springs than dropping a valve. Unfortunately, it will probably easier to get the broken stud out with the head removed on a work bench than over an open motor. Hopefully its not your DD.
Well, I drilled on that broken easy out for 3 hours and only got a good dimple in it. I gave up and a local speed shop is going to pick up the car and make the required repairs.

Where I didn't break any springs, do you think I still could have had a valve hit the piston?
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Old 05-16-2014, 08:31 PM   #12
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Quote:
Originally Posted by petsur View Post
Makes sense what you're saying. The guy that did the cam also did Comp's trunnion upgrade but did not use the new rocker bolts that come with the kit. He used the factory rocker bolts.
Epic fail! The new bolts are a must because they are about 1/4" shorter than stock. The stock bolts will bottom out in the blind hole and never clamp the rocker down... Ask me how I know. I had a reputable forum vendor make the same mistake on a new motor in my old C6 and I broke a rocker bolt on the track - I thought I lost another motor. I tried to easy out the bolt myself with no luck. I ended up taking it to a machine shop to get it extracted and help-coiled.

Pretty cheap fix, but I would be all over the shop that made this mistake!

Don't worry about the motor. As soon as that bolt broke, the valve stopped moving and shut that cylinder down. No other harm was done.

http://forums.corvetteforum.com/auto...the-track.html

Edit: if you can't find the head of the bolt, you may have an issue. You need to find it. Check all the oil drain holes?

Last edited by taken19; 05-16-2014 at 08:34 PM.
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Old 05-16-2014, 10:03 PM   #13
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Epic fail! The new bolts are a must because they are about 1/4" shorter than stock. The stock bolts will bottom out in the blind hole and never clamp the rocker down... Ask me how I know. I had a reputable forum vendor make the same mistake on a new motor in my old C6 and I broke a rocker bolt on the track - I thought I lost another motor. I tried to easy out the bolt myself with no luck. I ended up taking it to a machine shop to get it extracted and help-coiled. Pretty cheap fix, but I would be all over the shop that made this mistake! Don't worry about the motor. As soon as that bolt broke, the valve stopped moving and shut that cylinder down. No other harm was done. http://forums.corvetteforum.com/auto...the-track.html Edit: if you can't find the head of the bolt, you may have an issue. You need to find it. Check all the oil drain holes?
Yeah, I just crawled under the car again and can't find the fukr. There's no debris like it got chewed up and too big to fit in the oil drain. The piece that broke off was about 1" long.

I put a head of a bolt up to the oil holes and it's waaay bigger. Looked in the valve springs and don't see it.

If you look at the picture, the broken rocker was up high against the valve cover. I'm hoping it fell out when I pulled the cover off and wrestled it under the vacuum lines.
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Old 05-16-2014, 10:43 PM   #14
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I really hope you dodged a bullet in this case. I know if it were mine-the motor would come apart. Its one thing to have a failure and immediately shut it down-but that ride home would have me worrying.

I'd want to do a leak down, definitely check ALL the valve springs for seat pressure and make sure the involved valve is not bent. The lifter is another question. Fact is, the assumption in this thread is that the failure WAS the rocker arm stud- if the valve hit the piston from excessive rpm(highly doubtful-but possible) and was then bent which then jammed the rocker arm....etc.etc,etc- More than likely it was a JUST a stud failure. But dude,that is ALOT of IFS. Bottom line, you HAVE to account for EVERY piece of debris. Period.

Seriously, best of luck. It would really suck to have another part failure and potentially destroy the block and more.
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Old 05-16-2014, 10:55 PM   #15
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Quote:
Originally Posted by petsur View Post
Well, I drilled on that broken easy out for 3 hours and only got a good dimple in it. I gave up and a local speed shop is going to pick up the car and make the required repairs.

Where I didn't break any springs, do you think I still could have had a valve hit the piston?
One time I had a big block chevy with the dowel pin for the timing cover that somehow got driven inso it couldn't be pulled out. It was too hard to drill, so my dentist gave me some diamond burrs he used that fit in a dremel. They made a nice hole in the dowel pin so I could use a carbide tap on it to pull it out. Maybe you could get some of those diamond burrs from you dentist and grind out the easy out. Another method I've seen is to Mig weld a nut on the old stud, a lot of times the weld will hold enough to back out the bolt. Good luck.
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Old 05-16-2014, 11:35 PM   #16
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Yeah, I just crawled under the car again and can't find the fukr. There's no debris like it got chewed up and too big to fit in the oil drain. The piece that broke off was about 1" long.

I put a head of a bolt up to the oil holes and it's waaay bigger. Looked in the valve springs and don't see it.

If you look at the picture, the broken rocker was up high against the valve cover. I'm hoping it fell out when I pulled the cover off and wrestled it under the vacuum lines.
You have to find the bolt piece. Until you do, be very cautious on motor options.

Best of luck man.
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Old 05-17-2014, 07:59 AM   #17
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You have to find the bolt piece. Until you do, be very cautious on motor options. Best of luck man.
I know, but I don't see how it could fall into the engine, it's way too big. I didn't find debris like it shattered or was chewed up as I would expect to find small bits tucked around the head bolts and such. Other than the 1 rocker laying on its side, everything else looked fine. I'll put it up on jack stands again today and search some more.
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Old 05-17-2014, 08:35 AM   #18
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Take a magnet and swing around the engine bay. Maybe you get lucky and find the bolt.
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Old 05-17-2014, 09:41 AM   #19
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Take a magnet and swing around the engine bay. Maybe you get lucky and find the bolt.
. Yeah, I've been doing that.
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Old 05-17-2014, 01:07 PM   #20
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I did this once adjusting the valves on my solid lifter 327 ('67 Corvette Roadster). Ended up rebuilding the engine. I couldn't see an R&R on just one head to replace the rocker arm stud w/o doing a valve job too, after all, you go to the trouble to remove the head. One think lead to another so I ended up rebuilding the motor.
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