Had the top half of the intake off (2.3L) and fixed some vacuum leaks and replaced a power steering pump. Started truck and it ran funny like missing on one cylinder then cleared up then started making a loud knocking noise and running rough. Assumed that it swallowed something when I had the intake off and it got into a valve or into the cylinder. I pulled the plugs and there are no obvious signs of a problem. I also did a compression test and all 4 were around 150psi. Put the plugs back in and started it and the same noise was there. Removed the serpent belt just in case it was power steering pump related and the noise was still there when I started the truck. Sounds like something is inside the engine still. Going to get a friends bore scope to check further. I guess I will split the manifold again and run the scope in there. Pending that I may also look down the plug holes with the scope. This is a major bummer. Not what I needed.

Perry

 

Ok I looked into the intake and the spark plug holes while cranking the engine and there does not appear to be any debris in the cylinders or the intake. The valves are moving and look fine. I don't know what it going on here unless a lifter just decided to collapse on me. It sounds like a valve train noise. The timing belt looks ok.

Perry

 

Was it making any kind of untoward noise Before it was opened up for the work???
Since you've mentioned it sounds like valve train noise, has the Timing belt ever been replaced???? Thinking maybe its jumped a tooth or two & valve timing is off.

 

The timing belt was replaced not too long ago. The belt still looks new. It is a non-interference engine so I can't see a tooth mattering that much. I put a new power steering pump on it and had the intake top half off. It ran a little funny when I started it up but it did not make any noise and it started after a minute or so. I think I am going to pull the valve cover and see what I can see.

Perry

 

Ok, good feedback about the timing belt having recently been replaced & it running quiet on the restart for a minute, Before becoming noisy.
Could be a noisy lifter & suppose, since it wasn't noisy right away. Has it previously had a noise session like this after a start???
Had you by chance also just changed the oil & filter after doing the work???

 

No oil change. Pressure is good. Never a valve lifter noise out of it. It does have 270k on it some something might have decided to just go. Whatever it is, it acts like one cyclinder is dead but all have good compression.

Perry

 

Ok, more good feedback, well maybe your right that the noise is just coincidental, let us know what you find under the valve/cam cover.
Is the noise like metallic clacking, sorta like steel ball bearings in a sack clacking/clicking together, called "marble noise" or more like a tic that a collapsed lifter would make???
CCDF=Combustion Chamber Deposit Flaking, from deposits detaching & holding a valve open, can happen suddenly & cause rough running & upper end noise & since your ride has mucho miles on it, how did the combustion chamber piston, head & valve deposits look on the bore scope investigation????

 

FWIW, I once had a BMW motorcycle get enough carbon build-up on top of the pistons that it started hitting the cylinder head. The knocking that I heard only happened when the engine was cold and after a de-carbonization, all was quiet. The bike had 70,000 when this happened (back in '81).

 

^+1, its called CCDI=Combustion Chamber Deposit Interference & my 99 Ranger 4.0L suffered from it early on, until I learned how to use a combination of Techron Concentrate Plus & the high rpm portion of the Ford 4.0L decarbon TSB during the treated tank of gas, twice a year. It's been quiet for about 10 years now!!!! My CCDI at cold start up sounded like marble noise. Like a couple of steel ***** clacking together & it would go away after the engine warmed a little & expanded enough that the piston crown deposits stopped contacting the head in the squish zone. The Techron & high rpm treatment removes enough deposits to keep things quiet. Using Top Tier fuel also helps keep valve & combustion chamber deposits under control for me.

 

No deposits that I can tell. There could be something stuck in an exhaust valve but I can't get the bore scope in there to tell. The intake valves are all moving the same amount but I can't see the exhaust valves through the sparkplug hole and the camera won't fit in the hole. It will be pretty obvious if one of the exhaust valves is stuff open.

Perry

 

After thinking about it, if a valve is stuck open, seems to me the compression readings wouldn't have been as good as they were. Will be interesting to hear if you find anything under the cam cover. Did the back sides of the intake valves seem to be clean???

 

Ok I took the valve cover off and there is not indication of anything wrong. It looks brand new in there thanks to Mobil 1. I checked to make sure all the lash adjusters were working and none of them had slack on the round part of the cam. So it is not looking like a top end problem.

If the timing were really far off could it make this kind of noise? I don't want to tear into this engine just to find it got out of time. I mean spark timing which is totally computer controlled. I did not check the computer after the noise happened. I will have to put it back together yet again to run it long enough to get a code. This is a dammed if you do dammed if you don't problem for sure. I am not sure where to go from here.

Perry

 

Ok, can you be more descriptive of the sound, is it a tap, click, clack, clunk, is it a metallic sound & does it seem to be from low down toward the oil pan, or midway, like around where the block & head meet, or is it more to the top end around the cam & is the sound more toward the radiator, or firewall end of the engine, & louder on the driver, or passenger side????

Use a stethoscope to try & pinpoint it. If you don't have one, you can fashion one from a piece of rubber tubing, broom handle, long screwdriver, one end to the suspect area, the other end to your ear.

So, if you can be more descriptive of the type of noise & the location it seems to be coming from, the forum may be able to make suggestions as to where & how best to look next.
If you can make a recording of the sound & post it & tell us how long it takes for it to begin making the noise, that might be helpful.

 

Ok I found what looks to be the head of a screw stuck to the top of the piston. It looks to be embedded which means I will have to pull the head to get it out of there. I am hoping the threaded portion is gone and not deep down in the piston.

Perry

 

OK, good find & feedback, let us know how this turns out.