lraffe1 Posted May 18, 2010 Share Posted May 18, 2010 I have a 97 f250 that came in for a hard start and runs rough. i found high to low open codes for right bank. I ohm checked all wiring and injectors and okay. I then replaced idm and codes were gone. the engine still ran rough and started hard but wouild always pass cyl balance. I the removed and tested injs. i found number 7 inj was bad. i replaced inj and o-rings and returned to customer. customer had truck for 2 days and was driving down road started hearing a load poping noise coming intake tube. i took off left valve cover and found number 6 push rode bent and then broke. I then swapped number 4 push rod and cranked eng over by hand and valve appears to move freely. i also noticed that popping noise is louder with valve cover off. the push rodit also ripped out the guide in headgasket. which could have possible caused headgasket to fail and give it that load popping noise. any opinions if i should replaced push rod and rocker first then see what happens or go ahead remove head and inspect. Quote Link to comment Share on other sites More sharing options...
Keith Browning Posted May 18, 2010 Share Posted May 18, 2010 I have some nice pictures of a shattered and bent push rod from a 7.3L caused by a seized valve. I have come across seized valves in all three Navistar built Power Stroke engines. Some have resulted in broken parts like the push rod, a rocker and one snapped off the end of the valve at the keeper. I realize this engine is 13 years old but it is still possible for a valve to seize in the head if the right circumstance exist. If it were me I would be considering pulling the cylinder head to inspect the valve stems and guides. It is possible for a valve to move when cold and bind once the engine gets hot. The root cause is usually rust combined with a little gummed up oil and carbon. Good Luck! Quote Link to comment Share on other sites More sharing options...
lraffe1 Posted May 20, 2010 Author Share Posted May 20, 2010 I pulled all push rods on engine and checked. I found that both push rods were bent on 6, exh was bent on 4 and intake was bent on either 2 or 8. Truck orginal had a bad idm with a right bank high to low circuit open and also a failing 7 inj. I replaced idm, inj, and o-ringed other seven. I cleared cyl with glow plugs out like I have always done installed glow plugs and ran fine for 200 miles. Then number 6 exh valve bent, could it be possible that the failing idm and inj could have stressed the properly firing left bank enough to damage push rods or even bottom end. although it has been one of those months and maybe i just fdup amd didn't catch it. any thoughts or suggestions Quote Link to comment Share on other sites More sharing options...
GregH Posted May 22, 2010 Share Posted May 22, 2010 I had one some time ago that had a rod cap bolt back out or break... The cap separated from the rod slightly, allowing the piston to rise higher in the cylinder, and pause before descending when the crankshaft pulled it down. Popping noise in the intake was the symptom, and the initial finding was a broken rocker arm on one valve. Should be a picture or two on here... Quote Link to comment Share on other sites More sharing options...
GregH Posted May 22, 2010 Share Posted May 22, 2010 Here's the broken rod cap bolt picture... Quote Link to comment Share on other sites More sharing options...
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