Question about 2007 Chevrolet Cobalt Coupe

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Rocker arm failure

I have replaced head gasket, cam, rocker arms and lifters in my son's 93 Sunbird. SOHC. No2 intake rocker has broken twice since. Replaced lifter and rocker both times. Car is rapping again and I know No2 is culprit. What could be problem?

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  • nosocks Sep 12, 2009

    Ty for reply. I have replaced the belt, but it had not broken.. In this engine it is a non interference engine so the valves would not hit piston. Thanks anyway!!

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Did the timing belt break at one time? Aside from the obvious of it sounding like your son did what mine did and tried to race the vehicle beyond it's abilities if the timing belt broken at one time it may have damaged the valves. If the valve impacts the cyclinder it is possible that it can damage the rocker and cam. When you pull the head off this time have the head re-worked and valves replaced. This should solve the problem.

Posted on Sep 12, 2009

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Ok so ik I'm posting allot haha but does anyone know where or how to adjust lifters just found out mine r just now needed adjustment in near mount Vernon WA or a price at least haha


In engines with rocker arm valve systems, the procedure I'm familiar with is to remove a rocker arm cover, and (one at a time!) while the engine is running, slowly back off the rocker arm retainer nut or bolt just until you hear the lifter tapping, then tighten it a quarter turn. If you can identify a lifter that is already tapping, tighten its rocker arm slowly until it stops tapping, then adjust it. Do not over-tighten! This can damage the engine.

Listen carefully to how the engine sounds; if it starts to stumble when you tighten a loose rocker arm, you've gone too far. If you cannot get the engine to run well without tapping, you may have too much wear in the valve train and may be due for a head overhaul, or you don't have adequate oil pressure in the lifters in question.
Repeat until all rocker arms are done. Replace the rocker arm cover using a new gasket, then (in a V-engine), repeat the procedure on the other side of the engine.

Wearing safety goggles, or better yet, a transparent face shield, is strongly recommended. Sometimes oil will squirt out a considerable distance from the lifter side of the rocker arm during adjustment, and the direction is not readily predictable.

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  1. Start the engine, and let it run for 5 minutes, then turn the ignition switch to LOCK (0).
  2. Remove the cylinder head cover.
  3. Set the No. 1 piston at top dead center (TDC).
  4. Move the intake secondary rocker arm A for the No. 1 cylinder. The secondary rocker arm A should move independently of the secondary rocker arm B.
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    2. If the intake secondary rocker arm A does not move, remove the secondary rocker arms as an assembly, then check that the pistons in the secondary rocker arms move smoothly. If any rocker arm needs replacing, replace the secondary rocker arms as an assembly, then retest.
    3. Repeat step 4 on the remaining intake secondary rocker arms with each piston at TDC. When all the secondary rocker arms pass the test, go to step 6.
    4. Check that the air pressure on the shop air compressor gauge indicates over 400 kPa (4.0 kgf/cm2, 57 psi).
    5. Inspect the valve clearance.
    6. Install a 10 x 1.0 mm adapter to the inspection hole, then connect the air pressure regulator
  5. With the specified air pressure applied, move the intake secondary rocker arm A for the No. 1 cylinder. The secondary rocker arm A and secondary rocker arm B should move together. If the intake secondary rocker arm A does not move, remove the secondary rocker arms as an assembly, and check that the pistons in the secondary rocker arms move smoothly. If any rocker arm needs replacing, replace the secondary rocker arms as an assembly, then retest.
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My son has a 3.1 v 6 Lumina engine & was replacing the head gaskets. and he may have gotten the push rods in the wrong place, for someone that has never been in a engine before it is I guest easy to...


Hello ahbryantav66,

Intake push-rods measure 144.18 mm "the short ones".
Exhaust push-rods measure 152.51 mm"the long ones".

Below is an image of the top of a 3.1; in red are the exhaust rocker arms, in blue are the intake rocker arms. The other head follows the same pattern just examine and follow the ports.

netvan_117.png

Torque the rocker arm bolts to 124 in.lbs. plus 30 degrees.

I hope this helps.

Regards,

netvan

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