Hi Guys, I am writing everyone on here asking for help as a last ditch effort. I have a 2003 Dodge Ram with the Hemi 5.7. One night while hammering the gas pedal it made a loud metallic squeal type of noise in the upper RPM range. Immediately after it ran very rough, had a MAJOR loss of power and developed a loud tapping sound. I want to reiterate that this isnt your normal Hemi tick type of tap either. It is pretty darn loud.

So i replaced the lifters after reading the problems everyone else was having hoping it was a stuck lifter. This did not affect the tapping sound, major loss of power or rough idle at all and was a complete failure.

I have now taken apart the engine down to the camshaft. I have also completely disassembled the heads. I cant find a dang thing wrong with anything I am looking at.

Valves: Good
Valve Seats: Good
Valve Springs: Good
Camshaft: Good
Push Rods: Good
Rockers: Good
CEL Codes: Zero... which is amazing to me.

I know this leaves the rod or main bearings as a failure point for the tapping noise but I wouldnt assume bad rod or main bearings would cause this rough idle and loss of power.

My inspection techniques may not have been perfect but the items I would suspect to be the culprit look fine to me. Maybe there is something I have overlooked? Anyone have any ideas?

The next step is to buy a new engine if I cant figure this out. Any help is much appreciated.

 

I know hind sight is easy to say but should have tried to diagnose it a luttle further before teardown. Whats done is done. I dont know of a reason for rough idle from what you have described other than a cam shaft timing issue ? I think your next best option is to continue with a tear down. A loud knock usually indicates bearing or piston faiulure. Is there any evidence of a piston hitting the head by chance?

 

Thanks for the reply Dogman.

Yeah, I wish i would of done more diagnosis while the engine was together. I was just thinking about that earlier.

I checked the timing before I pulled the cam out and it was dead on. Timing chain tensioners looked nice and tight.

There is no evidence of any damage in the combustion chamber of either the heads or cylinders.

 

Depending on the engine sometimes lower rod bearing failure will allow the piston to contact the cylinder head and resulting knock some carbon deposit off the top of the piston and head...I am a little baffled as to the metallic squeal you heard as well as the rough idle afterwards....

 

Check and see if the accessories/tensioner/etc. turn free and easy. A seized bearing in an idler pulley can make some truly interesting noises, the additional drag can make the engine struggle at idle.

 

Exactly right , check ALT pulley and water pump pulley an anything with a bearing that can turn