6.9 engine knocking

[barryo]

I have 87 f-250 with 6.9 engine that recently started knocking,like a rod or spun bearing.Service manager at a local ford dealer thought more likely the knock is from injection pump or injectors.The truck had 105,000 when I got it.It now has 216,000 miles,I changed injectors at 165,000 and have done nothing to the pump.The 6.9 was always a good runner,I have never added coolant to it,and it uses about 1quart oil per 1500 miles and I always changed oil about every 3000 miles.
The service manager said that engine was built tough and rod or bearing problems were unlikely and leaned on pump bad or being out of time could make the engine knock.
Anybody else have similar problems?

[cdnsarguy]

I would ask did you replace any GPs lately. Also have you removed the rocker covers to see/listen to the valves/rockers........ there have been bad roller lifters in the 6.9 and the wheels have cracked and done damage to the cam. Of cours incorrect ops of the lifter relates to incorrect valve ops and possible noise. These are all possibles but until you remove the valve covers and check........ only my friend Clark Kent can see for sure!!!!

A bad injector firing early will also cause a bottom end knock...... how bad is the noise.

[arthurgoboom]

I would try the loosening of the injector lines while idling, one at a time, to see if the noise goes away when you loosen a specific injector line. When you loosen the lines the fuel leaks out instead of firing the injector. If it's an injector problem the knock will go away when you turn the fuel off to that injector.

Just beware of spurting fuel since it can potentially pierce the skin and make you take a dirt nap. Maybe wrap a shop rag around the top of the line nut when loosening.

[sundownersc]

Just had a friend that had his 6.9 start knocking badly and it turned out to be an injector stuck wide open. It sounded like it threw a rod bearing.