My '04 Pontiac Montana just spent three days in the shop getting a loose rocker arm fixed that also caused a bent push rod. The tech tells me this is very rare, in fact he's never seen it and has no idea how it happened.
It should be noted that at about 10K the head gasket blew and this same shop did the work. Do the techs need to mess with the rocker arm when repairing a head gasket? If so, I believe I have found my culprit.
You dont say what kind of engine you have in the Montana (I dont even know what is available in it), but if you change a head gasket, you have to remove the head, and that entails the valve train.
What do you think happened?
I think when the techs were in repairing the head gasket they did not properly re-attach or tighten one of the rocker arms. Between that time and now the arm worked itself loose and cause the damage. They were the last people to touch the part that failed.
You would be correct likely.
Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's Canadian Off Road Trips Photos: Non members can still view! Jan/06
I'll take a swag and say its a one of the 2.8/3.1/3.4 purhrod v6 family, which I'm pretty sure has conventional Chevy-style ball-stud rockers. Pushrod Chevies have always occasionally popped a rocker stud out of the head, which is one of the many weakness of the ball-stud rocker arm design. An overheat can contribute to loosening a stud in the head, too.
Others may well be right in saying that the guys that fixed the headgasket didn't assemble the rocker correctly, but its ENTIRELY possible that they did everything right and the stud still popped out with no warning and no way for them to have predicted it.
It's not unheard of for the rocker stud to pull out of the cylinder head. Small block Chevys have been known to do this for decades, your Montana van has aluminum heads making it -that- much more possible. I've seen Chevy 3.1 V-6s (sister engine to your 3.4) with the entire roof of the intake port pulled off.
The mileage when the rocker failure occurred is?
Not necessarily. There are tools and techniques that make it possible to remove the push rods without having to loosen the rocker arms on this engine family.
Proving so will be difficult given this engines' history WRT chronic failure.
This happened a LOT in earlier versions. You had to go in and pin the stud within the tower to stop it.
Typical GM bullshit.
Everyone, thanks for all the advice. The repair shop didn't charge us for the repair. They didn't admit fault, but in reality that's exactly what they did as they didn't argue the bill at all. Once they went back and discovered that they worked on the head gasket it was pretty much over at that point. Thanks again all.
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