Thread: Popped Rocker Arm Question

Ok guys so on one of my motors the #3 rocker arm on the intake side popped off. The initial problem that led me to remove the valve cover was that I had 0 compression in the #3 cylinder. The rocker arm had been pinned on the right side. I'm thinking that the valve was held open because of this causing my 0 psi problem.

I'm going to run a compression check without the rocker arm in place. I'm just wondering if that valve might be bent from being held open by the loose rocker arm.

For the guys who have had a rocker arm come loose. Have you also had a bent valve because of it?

If the rocker arm comes off, the valve stays closed, not open because the valve is still being held shut by the valve spring. the rocker just transmits force from the cam lobe to open the valve.

So you did a compression check before finding out the rocker was thrown?

If so thats why you had no compression. lol. Intake valves were not opening so what happens is the piston creates a vaccuum in the cylinder than then when back up it comes back to 0. You are probably fine. Was the rocker in 1 piece still?

If so just find the shims if you havent already and toss it back in there. No need to even remove the cam to do it. Just loosen up the cam caps with the motor at TDC the cam will lift up enough from the one open valve pushing upards on it to allow you to slip the rocker arm back under in place and pop the shims back in. Easy squeezy. Tighten the caps back down and torque to 90 in-lbs or so.

What initially happened was that I realized that I was running on 3 cylinders. My next move was the compression check.

The rocker is still in once piece. It just has a gouge on the left side. The cam lobe also has a gouge on the right edge. Part of one of the spring retainers has a chew mark, and part of one of the head bolts has a chew mark. The shims were close by. Luckily they didn't travel to hidden areas of the motor.

My plan is to pull an intake cam, rocker arm, and shims from a spare motor I have in my garage.

if the ding isnt bad just take a file to it to take any burrs that might be sticking up and if you have a spare rocker throw it in there. Might as well. But if you feel more comfortable replacing the cam then go for it if you have it sitting around.

Yeah not likely to have bent the valve. Thats why you had no compression as I said. lol. Throw a rocker in there and should be back to normal.

Well Gents I put the rocker back in place with the shims that popped out. I left the original cam in place. I start the car for a few mins. Still running on three. I open up the valve cover again and surprise surprise the same rocker arm is off again.

I'm thinking of why this thing popped off a second time. What do you guys think? Is this looking like a hydraulic valve lash adjuster problem?

Could be, or a shimming issue. The HLA is easy enough to bleed or swap from another rocker to test, so I'd start there.

Please do not do this!! This is an easy way to destroy a set of cams, rockers, and cam caps!!

Boostlee I followed the FSM tightening procedure. Thanks for the warning though.

If you loosen them up evenly with the motor at tdc there is nothing to worry about. Tighten in sequence of course and torque. Ive done this several times without issues. I dont know where you went wrong or where your getting your info from.