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This is a beautiful, Single Rear Tires, truck with 113k on it. This morning, it started a weird, periodic TAP, TAP, TAP, TAP, TAP, then 1 second of silence, then the TAP repeated. It is NOT a drivetrain issue and it's rapidly getting worse. At first it only did it under load. Now it does it idling. Enclosed, is an audio file of the sound with the hood up, standing near the motor on the driver, then passenger side. The gage is showing 32 PSI oil pressure at idle. What do you think?
I’d pull the valve cover and see if your valve train is good, sounds Iike a valve or valve spring retainer let loose or valve seat and is making contact with the piston.
Thanks for the advice. I had to go out of town . . . now checking. I pulled the valve cover. I don't see anything obvious with the springs or rockers. There is a code for a #2 cylinder miss. It's interesting that the engine went from a "rolling, cyclical knock: (Several quick knocks, followed by a period of silence, followed by the knocks again) to constant knocking & squealing at idle. I'm beginning to think Valve Seat. Any further thoughts on your part? My next thought is to pull the injectors and place a video scope in the holes and check for piston contact with a valve. Does that make sense to you?
I pulled the head off. There's nothing obvious with the valves or the pistons; especially, for a noise of that magnitude
All pulleys, including the A/C have been checked and cleanly spin. The serpentine belt looks decent - not burnt.
The Turbocharger spins freely.
The sound started out as a "rolling tap". Tap-Tap-Tap, followed by a couple of seconds of no noise, the Tap-Tap-Tap. . . repeat, but within a day, even at idle, the noise became continuous, squeaky sounding (possibly like metal to metal slippage). It sounded scary, like something was about to break or lock up.
If it is a loose valve seat, I can't tell it with the naked eye. Tapping the valves with a hammer - They all act about the same. There's nothing sticking; though perhaps, a loose seat won't necessarily show physically right away??
Anyway, regardless if any of this rings any diagnosis bells for you, I'd love to hear your opinion!
BTW, I don't intend to go back with the same head or injectors. What would you recommend?
Last edited by ecnels; 09-18-2018 at 03:43 PM.
Reason: Added Pics
I drained the oil through a cloth and found one small metal flake, then I pulled the oil filter, cut the "can" off of it and removed the pleating: SURPRISE!! See Pics
The other surprise was that when I removed the oil filter from the engine, it was only about 1/2 full of oil. I've never had a filter be less than full when removed for an oil change. The oil level in the truck was full before draining the pan - I check it every fill-up.
This serious-knocking happened suddenly - over the course of 3 running hours it grew from a small cycling Tap-Tap-Tap-Delay a couple of seconds, Repeat, to a steady knock - increasingly louder until it became ominous.
Yeah I'm about to do it. One clue, I've changed maybe a couple of hundred oil filters in my life and every one has been tip-top full when removed. This one was half full. I'm trying to figure out how that could be, because something would have to create a vacuum, scavenging effect to be able to pull the oil from the top of a vertical filter can.
09-08-2018, 01:51 PM
