Broken Rocker arm and bent pushrod

czimpel

czimpel

Boost...gotta get some!
Joined
Aug 16, 2012
Was this a fluke, or do I have something messed up? Haven't had this issue before, but just got the motor back together. Can having not enough lifter preload cause this by chance, because I did use shorter pushrods than the previous time to get my preload in check. I'm wondering if I got it too loose by accident. There wasn't any valve train noise before this happened. Had kind of a lot after it did. Lol.

#5 cylinder. Exhaust rocker broke and intake pushrod is bent.

IMG_7651.JPG
 
Did you pull the head?
How long did it run before this happened and was it running good?
You say exh and intake so a lot is going on here...
...
 
Budget 4.1 • ATR Billet Roller RP309G • Champion Ported Irons setup with roller springs.
It was running good. I pulled the motor due to milky oil, I didn't find any issue visible to me, but this now has just happened with about 20 miles on it after getting it back together.
 
The rocker does not look hot at all, and they are oiling. It was the exhaust rocker that broke, and it's pushrod is straight. The intake rocker on the same cylinder is fine, but the push is bent.
 
Looks familiar... but most wouldn’t believe what it was if I told you. How much boost were you on?
5F92D1B7-B154-48C5-A52E-FC9B09DA79BA.jpeg
 
ATL_87GN
Are you thinking the head lifted and the shaft flexed enough for the pushrod to deflect out of it's rocker pocket?
Kinda looks like that from the wear on that rocker in your picture.
Or something else?

I'm a firm believer in upgrading to either Harland Sharp or T&D's with hydraulic roller cams. Given, there are a lot of guys out there that have run stock rocker setups with roller cams without any issues, but I just like the beefiness of the aftermarket rockers.

Definitely need more info.

-Patrick-
 
I did the same thing but my pushrod dropped into the cylinder head. I havent seen damage to a rocker like that before. Mine was exhaust #4 cylinder. Maybe the valve kissed the piston. If I read it correctly the exhaust rocker and intake pushrod on the same cylinder.....the only items in common that could have been changed 1- pushrods - went shorter (you lessened the preload) 2- piston - was a new piston designed used on the rebuild and / or if it had valve reliefs cut in was it installed correctly (????) 3 - was the head shaved any to clean up the surface (????) 4 - was a different ( thinner) head gasket used than previous (????) 5 - did you disassemble any thing other than just removed the heads to replace the head gasket or did you tear the motor down? Can you provide any additional details ? It completely blows people minds if they ever see the valve cover off, the simplicity kills them.
 
rag231 said:
I did the same thing but my pushrod dropped into the cylinder head. I havent seen damage to a rocker like that before. Mine was exhaust #4 cylinder. Maybe the valve kissed the piston. If I read it correctly the exhaust rocker and intake pushrod on the same cylinder.....the only items in common that could have been changed 1- pushrods - went shorter (you lessened the preload) 2- piston - was a new piston designed used on the rebuild and / or if it had valve reliefs cut in was it installed correctly (????) 3 - was the head shaved any to clean up the surface (????) 4 - was a different ( thinner) head gasket used than previous (????) 5 - did you disassemble any thing other than just removed the heads to replace the head gasket or did you tear the motor down? Can you provide any additional details ? It completely blows people minds if they ever see the valve cover off, the simplicity kills them.
Click to expand...

Just pulled the heads to check gaskets. Pulled a couple rods and mains to double check bearing. Other than that it is exactly as before except the pushrods and timing chain set. Same Fel Pro 1000 gaskets.

Running ARP head studs, so the head should not be lifting at 20psi.
 
czimpel said:
Morel lifters. Only 20-21 boost. Never had any issues before. The only change I made was replacing the TC set with a T/A billet set. I was on it when it popped.
Click to expand...
Take a peek at the cross shaft for the roller they have been known to fail. The swedging fails and pin moves
 
The issue, bent push rod, I had was not apparent until the boost was pushed past 17psi. The notorious exhaust lobe on cylinder 3 was wiped. As we increased the boost to 24psi the exhaust lobes 0.134” lift was not enough to evacuate the combustion pressure. On the next cycle the intake valve was having to fight so much pressure it was bending the weakest point, the hollow push rod. I replaced it once to see and it drove fine until I went over 20psi. Amazingly, the car actually idled fine after it was bent, but made a tick like a lifter. After replacing the camshaft and lifters the car pulls 25psi with no issues and also picked up 14mph in the 1/4. I would also be curious if the lifters, lobes or cam thrust is off.
 
I'm on a roller. I tried to look at the cross brace last night, and as far as I can see it is still in place. #5 is hard to see. I can see every other cross brace with ease on that side.
 
I bent a push rod street racing and it looked identical to yours...I had a flat tappet cam and one of the cam lobes were wiped out
 
broke said:
Either of the springs appear to be broken?
Click to expand...
No. I put a new rocker and pushrod in and it runs perfect again. Haven't driven it under boost yet, but seems ok at this point. I'm just seeing if anyone has had this happen so I could check for possible issues.

Thanks, Cory
 
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