cylinder 2 misfire

[SpencerA]

My 2001 Venture (v6 ) has a error message of PO302. This is apparently a misfire in cylinder 2. Initially I heard a metalic clanging sound that eventually stopped after a few minutes. The van is running very rough but still seems to have good pickup when I givce it gas. Any ideas on where to start in order to figure out the problem? About 3,000 miles ago I replaced the intake and head gaskets and had no problems until now.

I'd appreciate any help, thoughts or ideas.

Thanks
SpencerA

[ChoochCharlie]

My misfire on cylinder 2 was a cracked head, block or head gasket.
Hope you dont share the same cause.

Check for coolant in the cylinder and a wet sparkplug.

[SpencerA]

Thanks for the reply. I removed the cover to my cylinders and discovered that one rocker bolt was stripped and on the other rocker the push rod was bent. I know the cause of the stripped bolt and am going to repair that with a heli coil (sp). However, I do not know why the push rod on the other rocker was bent. I plan to replace the rocker and the push rod but would like to have some idea as to what happened so I can attempt to avoid the same problem in the future. I am wondering if the rocker bolt was to tight and resulted in the push rod bending against the resistance?

[bleepster]

just a guess here, but when you redid your intake, are you 100% sure you put the push rods back in the SAME spot?

I wonder if you accidentally swapped 2 rods, resulting in your damage.

what caused your stripped bolt?

[SpencerA]

Sorry for the delay I was out of town. I checked with GM and I did not have the pushrods reversed. However, the stripped bolt was so loose that I was able to simply pull the rocker arm out without loosening anything. It was also sitting sideways. I thin it may have hit the rockerarm next to it and caused the bent pushrod. The bolt was stripped when my buddy used a ft pound torgue wrench instead of an inch pound. As you can imagine, he stripped the bolt. Unknown to me he put locktight on it and never told me about the stripped bolt and his "repair" (he claimed he was still able to torgue it to the proper setting) until after after the engine was put together. I just finished installing a helicoil last night and it appears to have worked.

[SpencerA]

The saga continues. I put everything back together last night and started the van. I had a metalic clicking sound that increased when I gave the engine gas and decreased at idle. I changed the oil and put in Marvel's mystery oil, however, the clicking continued. I went to bed convinced that I had a bad lifter. This morning I removed the valve cover again and found that the rocker arm I put the helicoil in was loose. The bolt was not loose and was still torgued properly (168 plus 30 degrees) the rocker pedestal was firmly in place but I could turn the rocker arm clockwise and counter clocwise about 20 degrees. When I did that the pushrod had lots of play. I am hoping that the rockerarm needs to be replaced and that the clicking sound will be gone. Any thoughts?

[Doc Doug]

Any luck with the rocker arm repair?

I have a 03 Rendezvous with both the intake and exhaust rocker arm bolts stripped from the intake. Ughhhhh. I would like to helicoil repair before I consider pulling the head.

[DRW1000]

Originally Posted by SpencerA

The saga continues. I put everything back together last night and started the van. I had a metalic clicking sound that increased when I gave the engine gas and decreased at idle. I changed the oil and put in Marvel's mystery oil, however, the clicking continued. I went to bed convinced that I had a bad lifter. This morning I removed the valve cover again and found that the rocker arm I put the helicoil in was loose. The bolt was not loose and was still torgued properly (168 plus 30 degrees) the rocker pedestal was firmly in place but I could turn the rocker arm clockwise and counter clocwise about 20 degrees. When I did that the pushrod had lots of play. I am hoping that the rockerarm needs to be replaced and that the clicking sound will be gone. Any thoughts?

Do you mean that the helicoil itself was losse? Could this be because the aluminum casting expands more than the steel helicoil?

[a_joyner]

Did you put the pushrod's back in the exact spot they came out of? The pushrod's, lifters, rocker arms wear at different rates and must be put back in the same order they were taken out. That could be your problem. Not sure a helicoil will solve the problem....may have to replace the head.

[cdru]

Guys, SpencerA only has 5 posts, 4 of which was in this thread, and the thread was started over a year ago. You can probably safely presume that he isn't going to respond.

Doug, a Helicoil should work if you can get access easily to drill out the old threads and tap it.

DRW1000, It likely wouldn't be caused by the difference in thermal expansion. Helicoils are quite often used to repair stripped spark plug holes in aluminum blocks. The thermal expansion coefficient of aluminum as compared to steel (or iron) is around a 2:1 ratio. A 1/2" hole hole would expand less then a 5 thousands of an inch over a 800 degree temperature range, making the "gap" between the helicoil and the head 25 ten-thousands of an inch. Your just about to precision of most machining anyways so it's almost negligible in this case.

[shooter_va]

Here is another product that can be used instead of an Helicoil (depending on the application):
http://tds.loctite.com/tds5/docs/FORMSTRK-EN.pdf

[Sparky1349]

Originally Posted by shooter_va

Here is another product that can be used instead of an Helicoil (depending on the application):
http://tds.loctite.com/tds5/docs/FORMSTRK-EN.pdf

Hey Shooter, Not sure if this is a good application for this product. The spec sheet calls out max torgue for a 1/2" thread (I think this is close to the thread size of the rocker pedestal) of 193 in-lbs. As I recall from the other night the torgue proceedure is 18 ft-lbs (~220 in-lbs) then 30 degrees. At that torgue I don't think you can count on the Loctite product.

Spec sheet calls out typical uses like rocker cover bolts, oil pan, etc... all low torque application.

Best bet is to go with a Heli-coil or similar product.

Sparky

[Doc Doug]

Did you find your problem?