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Ticking/Rattling Sound 1991 12v Cummins

1712 Views 3 Replies 3 Participants Last post by  CrazyktmMatt
Just purchased a 1991 12 valve 5.9L Cummins D250. Pretty much stock except for 4" straight TBE.

There is a fast ticking/rattling sound (almost like shaking a can of spray paint really fast) from the engine compartment when lightly accelerating and also when letting off the gas/braking while still rolling. It doesn't do it every time. Only sometimes, and never when I'm trying to show someone. :banghead:

There is also another ticking sound that sounds like something tapping underneath the front of the bed between it and the cab almost. It's not as fast. Maybe 4 ticks per second and goes along with the idle when it does it. Also only happens sometimes.

The truck runs and sounds great. Starts on first crank. No stuttering or sputtering. Auto 727 trans shifts good and all.

[Edit] I did notice when the truck was in park this morning I could trigger the fast ticking/rattling sound (under the hood) by pressing in the brake pedal. It would start when I would press the brake pedal in then continue to tick for a few seconds after I let off the brake pedal and then slowly fade away.

Still can't figure out how to trigger the one under the bed. Was thinking maybe the lift pump from what I've found (googling and looking around forums) but this seems to sound different and faster than what people describe when it is the lift pump.

And the whole brake triggering the fast one under the hood is throwing me off too.

Any ideas on what either of these could be?
1 - 4 of 4 Posts
Could be the valves need adjusted, most people never adjust them.
Power steering/ vac pump loose?

Seen this happen on a truck.
1 - 4 of 4 Posts
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