2001 Jeep Grand Cherokee, P0505,P0302

Need some help with a 2001 Grand Cherokee. It overheated last week, was shut down to let cool. When restarted there was a loud knock. I pulled valve cover and found #5 exhaust rocker arm laying inside. I reinstalled the rocker arm, and valve cover. Restarted engine lound knock gone but now there is a dominent tick that sounds to be coming from the intake. Checked codes and found P0505 and P0302. P0302 misfire cyl #2 but what is P0505 and could it produce this ticking? Any help would be appreciated.

Why did it overheat? P0505 is a fault in the Idle Control Circuit. So the rocker arm came completely off? If you still have a tick and a misfire for Cylinder #2 I would pull the valve cover back off and check all the rocker arm bolts and make sure no others are backng off.

The engine overheated due to a faulty engine fan relay. All rocker arms are secure and in adjustment as they use hydraulic slack adjusters. With engine running and valve cover off this bank makes no noise. The only thing that seems to hold the rocker arm in place is the overhead camshaft, and yes the arm came right out and was laying on top of the head.

This must be a 4.7? If I had to guess the rocker arm came out due to excessive carbon build up on valves and that's probably where your misfire on cylinder 2 is coming from. The carbon is not allowing the valve to close and then causes the rocker to fall out. you can try some good top engine cleaner but if it's bad enough to make a rocker fall out more than likely the heads will have to be removed. Pretty common with this engine.

The cylinder the rocker fell from and the cylinder that is missing are different. #5 for the rocker and #2 for the cyl. Could be carbon on #2 but why lose rocker on #5? Think you are right with carbon on #5 Valve feels sticky but #2?? Sry. yes it is a 4.7

I understand that the rocker fell off number 5 and the misfire is on number 2 when valves carbon they all usually do to a certain extent. only other thing is the lash adjuster for the valves.

The easiest way to tell if this is the problem is to do a compression test and see if it is low

Thank-you, I will try a compression test and see what it tells me.

ok, sry for delay had some trouble getting back to the task. The compression is low on 2 and 5. Guess I'm pulling heads? Where would be a good place to obtain torque specs and procedures if this is the case? I don't suppose there is an easy remedy to remove carbon build up without removing the heads?

some specialized tools are required for the timing in that engine! the procedures can be located in a good manual or an alldata subscription

thanks jeff, will see what i can dig up