I have a 1994 chevy corsica with a 3.1 v6 that the stud on the rocker arm keeps breaking after about 700 or 800 miles. What is the problem with it?
This is a new one to me. My only guess is it’s being assembled too tight, or possibly there’s an actual valve problem, but what that problem might be, I’m not sure…springs too tight, maybe?
What could the valve problem be? I have some mechanically enclined family members and we cant seem to know what it could possibly be.
Also thank you for your input.
I have a few guesses…One is a valve that is too hard to actuate…Bent valve stem would do this…a galled valve guide/stem also… The head would have to come off to fix…but to be certain…pull the rockers on a few other valves…TIME…the engine properly for the test and push down other valves to see how hard they are to depress…then check your rocker breaker valve…Bet its harder to push down…
ALSO…hmm…a stuck or frozen lifter may be to blame also…if it is hydraulically locked up it may be pushing the rocker/valve too far…I’ve never seen that but theoretically it may be possible.
Most often you will bend the pushrod before breaking that stud…hmmm again…
DO NOT over push any valve…if excessive force is needed then you are hitting a piston…which is why I said TIME the engine properly for the test…Sa v vy?
Where is the stud breaking at? Is it breaking at the bottom or where the rocker pivots? Is it a press in or a screw in?
Doubt its a press in…they would’ve mentioned it no? Sounds like the swapped in a few already
Broken valve spring, bent valve stem…Pull the head…
Caddyman and others make another good point…I didn’t consider a broken valve spring…IF a spring breaks it can position itself such that it is impossible to move the valve thru its full stroke…It will Bind… This can do it also…sure. You need to look into the tests that we have laid out for you…a broken spring is on the list now…
In many of these instances…I would think that the pushrod would bent b4 anything else… Which is why I am still scratching my head a bit on this one.
BEFORE you pull the head…do the tests I and others have laid out…try to take that valve thru its full stroke looking for binding and or a broken spring etc… DONT forget to time the engine properly before depressing any valves… You can remove any spark plug…insert a long straight rod or bamboo skewer into the hole…bring the piston all the way up…and the HALFWAY down again…now that its halfway…so are the other pistons…they will all be halfway…then you can depress any valve you wish
A broken spring can allow a hydraulic lifter to pump up and over-extend, compressing the broken spring to zero clearance. Something has to give…The lifter itself may have failed and over-extended. Check that too…
If it was a broken valve spring, you would hear it, it makes a lot of noise. I asked about where the brake was occurring because the rocker may be worn so that it is no longer directly over the valve as it is actuated. Try replacing the rocker as well as the stud.
Keith makes a good point…Are there any noticeable noises associated with your issue? You have quite a few homework assignments…let us know what you find.
Didnt hear any noises, just a small tick at start up, quieted down a bit while driving and it was fine, just a bit sluggish, didnt quite accelerate as fast. Then on my way to school it lost a lot of power and had a big miss. Thats all i have with my spmewhat limited knowledge.
The tick is telling me that the rocker is slipping off center, wearing down the stud on the side and finally breaking. I had this happen to me on a 66 Ford 240 ci engine.