Another story from the service bay

clinebarger

clinebarger

Joined
Dec 19, 2013
Messages
7,477
Location
Fort Worth, Texas
2003 Pontiac Aztek, 3.4L/4T65E, 135,xxx miles. Compliant.....Misfire on #5 cylinder. Coils, ICM, Plug Wires, & Spark Plugs have been changed by another shop/mechanic. It is indeed misfiring on #5 cylinder, LT Fuel trims are hovering @ negative 6% at idle. Balance tested all 6 injectors, They were within 2% of each other. Vacuum gauge was steady but low @ 14 inches. Disabled spark & cranked the engine over, This revealed an uneven compression issue by the sound. Called the customer & got the okay to pull the Bank 2 (rear) valve cover, Back off the rockers & do a Leak Down test on #5. Pulled the cover & found the #5 Inlet Rocker laying on it's side. Threads pulled out out of the head, Pushrod was sitting off the lifter but was able the retrieve it with a pencil magnet. I made the decision to Heli-Coil it blind using a mirror & flashlight. I drilled the hole out by hand using a Tap T-Handle tightened onto a 21/64" drill bit, Was able to watch the angle compared to the #3 Inlet Rocker bolt while drilling & tapping for the Heli-Coil insert. Used liberal amounts of wheel bearing grease on the tooling to catch most of the aluminum chips/debris. Loctited the insert in & let it sit overnight, Broke the insert drive tang off with some hemostats, Ran in a thread chaser to clean out the left over Loctite, Torqued the Rocker Arm assembly down to spec. Barred the engine over & confirmed the Rocker had a little side to side movement (The lifter didn't stay pumped-up).....The lifter didn't want to bleed down by simply torquing the rocker. Engine now runs on all 6 cylinders, Let it run to operating temp & change the oil & filter. The Rocker threads were pulled during a LIM gasket change that was done by the same shop that sold all the tune-up parts. I checked the other rocker arm bolts on the rear bank...They held torque after back them off a little. Customer stated the engine ran fine for a couple weeks after the LIM gasket job. Please don't ask about the cost, It's probably more than you think it's worth, There are no book times for fixing screw-up's that shouldn't have happened in the first place. I will say it was cheaper than pulling the head & repairing it on the bench. [Linked Image from i.imgur.com] [Linked Image from i.imgur.com]
 
DiL had one of those for 13 years … hard to look at … but it was actually reliable …
 
Guessing by the sludge on the rocker parts & head , some one has not been changing the oil / filter too often .
 
Someone that actually figures out the problem instead of throwing countless parts at it is refreshing to see. Your stories from the service bay make for great posts. Job well done! cheers
 
Originally Posted by WyrTwister
Guessing by the sludge on the rocker parts & head , some one has not been changing the oil / filter too often .
17 years old, I'd guess "maybe", if it's been the same service all this time, then perhaps the oil is being towards its service limit. Then again, if oil is better than it was was 17 years ago, maybe not. Sounds like it was a fun job! Ouch.
 
My guess is the previous guy didn't bother with 14 ft.lb + 30° he just tightened them up good n tight. Nice job getting the helicoil in back there, its tight. This sort of damage shows the need for good torque tools especially when working with aluminum.
 
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An 8mm tapped into aluminum requires caution. Bug engines used a pair of them for the rockers. Caution, learned the hard way, 'cuz fools don't learn any other way. grin2 PS: I have the scars to prove it too. grin2
 
Very impressive to see someone actually diagnose a problem. Very impressed. sailing Keep us updated with more of your work.
 
Originally Posted by Gebo
Very impressive to see someone actually diagnose a problem. Very impressed. sailing Keep us updated with more of your work.
+1 Great job on the diagnoses and repair.
 
I did a LIM gasket on an Olds Alero with the 3.4 years ago and believe I remember using a special Lisle tool to compress the springs and remove the pushrods without having to unbolt the rockers. It was simple, quick, and avoided problems like this developing. Am I having a senior moment and remembering wrong? Or did the other shop unnecessarily complicate and add hours to a simple part of the LIM replacement job? And if they screwed this up, did they use the proper manifold replacement bolts (ones with the pre-applied thread lock) and torque them down correctly so the manifold doesn't start leaking again?
 
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