Rangoonboth

I was driving my Venture the other day and all of a sudden the engine started to run like crap. It felt like it was missing on one or two cylinders and the vibration was terrible. The check engine light was flashing when I was driving but stopped flashing when it was idling. My check engine light was already on due to an ox censor i hadn't gotten around to replacing yet so I don't know if it would have went off at idle. My mechanic was so busy and with the holiday he cant get to it this week. He took a quick look and said he took the oil cap off and noticed one of the rockers was not moving. He really couldn't speculate until he had more time to look at it but ti didn't look like good news for me. Could this be something like a bad lifter or more serious like a bad cam or worse.
Thanks

kevinkpk

Either running or cranking, did he say a rocker arm wasn't working? If you are sure, if it were me, I'd back the rockre arm off the stud as to clear to remove the pushrod. Count the number of rounds you back it off as to replace the rocker arm later with it close to what it is now. Drop a telescoping magnet after removing the push rod, remove the lifter. If the divit in the body isn't (edges) flush with the top of the body, it has collapsed. Replace it. If that is the case, I'd recommend you examine your maintenance schedule, i.e oil changes. BTW red in your quote is mine.

kevinkpk

Well, I should have added. If it is a lifter, drop it in a can of oil that you use in your car before installing it. If it dosen't appear collapsed, replace it anyway. If that isn't it, and still no rocker arm movement, I'd say cam shaft.

Rangoonboth

Thanks for the advice. He only took the oil cap off not the cover and looked in with a flashlight. If the cam shaft goes, wouldn't all the cylinders be effected? or can you just lose part of it.

kevinkpk

I'd not take anything he says if this is the case, else he was just lucky that the rocker arms he could see is the issue. That still dosen't check the entire valve train. No the cam shaft can round a lobe, had it in an 82 sbc truck. If you can do a compression test, that will tell you if a valve isn't(exhaust) opening due to a lifter. The cylinder pressure should rise, on the compression stroke, then drop when the exhaust valve opens. It's easy enough to pull valve cover.

dougmr

You can lose a single lobe off a cam. It's not common. It'd usually be a spring binding or other rocker/lifter failure.

However 3 things with this particular issue aren't consistent with a "full cam failure). First, "all-lobe" cam wear doesn't cause an issue where the motor just 'goes to crap' quickly, it's very eventual. Second, in a "full roller" motor like these, it's more likely a failure in the lifter, spring, or rocker (which could cause wear on just one lobe). Third, if it were a failed cam-bearing and you could see the effect from the middle cylinder (I.E. visible from the oil cap), that motor would be in dire straits. It wouldn't idle well at all.

Having said all of that, I'm not sure what your issue is. I do assume that your mechanic was mistaken, but he could be right.

As a parting shot, clean your MAF sensor before you replace your O2 sensor. I use MAF cleaner and a Q-tip with a gentle touch (as opposed to carb cleaner or no Q-tip). I've heard that carb cleaner leaves residue and the one time I used carb cleaner, it only worked for a couple days before the O2 sensors re-coded. The O2 sensor is probably bad, but maybe not.... Only 1 is coding? When I see both O2 sensors leave codes, I'm pretty sure it's the MAF.

Rangoonboth

Just found out it is a stripped rocker arm bolt that goes into the head. Either need a new head for $1200 or a helicoil for a lot less.

dougmr

Helicoil is stronger anyway.

Helicoiling head-stud holes is one of the first things we'd do to our home-brew racing heads.

I hope that $1200 is with labor!

Rangoonboth

He's charging me $120 to fix it with a helicoil. I believe it would be stronger. I just hope they don't all start going stripping out.