Help me Diagnose Knocking Sound

Hmmm.  5W20, it is not going to be an ecoboost on an MKX.  All ecoboosts on the Edge/MKX were 5W30 from the start.

Regardless, these engines are noisy to begin with.  Once you take the cover off, OH BOY!  I know Ford had issued TSBs on the naturally aspirated 3.5/3.7 due to noise, and there were some cam cap modifications involved IIRC.  Other than that, Ford has made no mention of anything related to engine noise in particular.

Doesn't sound like belt tensioner noise either.  At least mine sounded like cards in spinning bicycle spokes, and only on cold startups on cold days.
 
Okay more information.  I changed the oil today, I decided to go with and OEM FL500S filter and 5W-30 oil.  I also pulled the #1 and #4 spark plugs.  They have only been in the car for about 1,500 miles, but they both had a lot of carbon build up around the bottom of the threaded part of the plug, but otherwise looked fine.  I further investigated the noise while the car was up on ramps.  Using the mechanics stethoscope, the noise is loudest on the timing cover and on the oil pan.  It really isn't detectable from the valve covers.  It is noticeable on the timing cover in front of both heads.  I've also pulled the power to each ignition coil, one by one, for every cylinder, and the noise did not go away or change.  The sound does not appear to be emanating from the accessory tensioner, alternator or compressor.

I think that if it were a single cam phaser causing the noise, I'd expect the sound to be much louder on one side than the other and it isn't.  I'm beginning to narrow this down to the water pump, timing chain guide, a piston (cracked skirt), wrist pin or crank bearing.  The sound is clearly radiating through the block as I can hear it loudly through the aluminum oil pan.  I still feel that the water pump is the number 1 most likely culprit, but I'm not sure.  I'm open for ideas of what tests I can do to further isolate this.
 
ABS- I asked if you were monitoring KR, I never saw a response.

I asked because I had my entire timing set rebuilt under warranty. The only reason I caught it before the engine grenaded is because I started seeing KR at levels and places it shouldn't be.

For example, I would see +7 right off idle without boost.

There were NO issues at WOT either.

Interesting sidenote....KR pretty much doesn't exist since everything was rebuilt. The last 3 months the max KR logged was .79 with 15PSI and high 20s WOT spark. I was actually surprised at the .79 because prior to that, .09 was the max for a while. Since I reset the maxes its back to .09


 
FoMoCoSHO - I'll check for knock once I get the engine back together.

I decided to pull all the spark plugs today and also conduct a compression test.  The plugs look generally okay, the ones closes to the intake have more soot on them than the rest,but none were in terrible shape.

Compression results (tested with a cold engine and all plugs out):

Cylinder 1 = 200 psi
Cylinder 2 = 195 psi
Cylinder 3 = 187 psi
Cylinder 4 = 194 psi
Cylinder 5 = 190 psi
Cylinder 6 = 192 psi

I believe these are acceptable results, any feedback will be appreciated.

Next, I am going to rotate the engine, bringing each piston to TDC, and check each for any bearing play or movement.
 
abs said:
Okay more information.  I changed the oil today, I decided to go with and OEM FL500S filter and 5W-30 oil.  I also pulled the #1 and #4 spark plugs.  They have only been in the car for about 1,500 miles, but they both had a lot of carbon build up around the bottom of the threaded part of the plug, but otherwise looked fine.  I further investigated the noise while the car was up on ramps.  Using the mechanics stethoscope, the noise is loudest on the timing cover and on the oil pan.  It really isn't detectable from the valve covers.  It is noticeable on the timing cover in front of both heads.  I've also pulled the power to each ignition coil, one by one, for every cylinder, and the noise did not go away or change.  The sound does not appear to be emanating from the accessory tensioner, alternator or compressor.

I think that if it were a single cam phaser causing the noise, I'd expect the sound to be much louder on one side than the other and it isn't.  I'm beginning to narrow this down to the water pump, timing chain guide, a piston (cracked skirt), wrist pin or crank bearing.  The sound is clearly radiating through the block as I can hear it loudly through the aluminum oil pan.  I still feel that the water pump is the number 1 most likely culprit, but I'm not sure.  I'm open for ideas of what tests I can do to further isolate this.
Click to expand...
I would give it a couple key off cycles before any notable changes to the cam phasers itself!
Hmm! I thought you mentioned on your initial post the front phaser sounds different than the rear one!

Has the sound of the phasers changed any! TOL. Z
 
Well, I have been unable to determine the source of the noise so it went to my local Ford dealer today to diagnose the sound.  It does not appear to be emanating from the cam phasers and it does not sound like the cam phasers based on other videos I've seen.  It also does not make the sound when cold, but is very noticeable when hot.  I did hear somewhat of a variance in the sound of the phasers themselves and the vibration of the actuators from one head to the other, but I would be surprised if that is what is causing the sound.  Using the mechanics ears/stethoscope, I could clearly hear the noise at the oil pan (down its length) and middle of the timing chain cover.  I have seen some videos on YouTube where a similar sound was determined to be a damaged piston skirt.  So, I'm pretty sure it will be one of the following:  water pump, piston skirt, piston wrist pin, piston rod bearing, or crankshaft mains.  The engine has never run low on oil and has always been maintained with synthetic oils so I'm really hoping it is not a bearing, wrist pin or skirt.  If it is the water pump, I guess I'll be going in to replace the pump, guides, chains, tensioners and pump . . .
 
When they figure out what is wrong, and it is internal to the block, you may want to bring in Ford Customer Service.  After all, it is a remanned block and should last WAY longer than the warranty period.
 
Latest updates:

Brought the car to my local Ford dealer to have them evaluate it. Same as me, they were unable to identify what specifically was causing the noise. They think it could be piston slap, a wrist pin or a bearing. Their feedback was just drive it, it could last another 50k miles or more despite the noise. They tried shutting down cylinders and noted, as did I when I did the same test, that there was no change in the engine noise. To me this is a key fact! Piston slap, a wrist pin or a bearing should all change sound when the cylinder is de-activated. I asked them if it could be the water pump. The feedback was they didn't think so because they believe that the pump would be leaking coolant badly if the bearing was starting to fail allowing the impeller to hit the block.

Now, having said all that, I still think it could potentially be the water pump. My recollection is that the area of the block that the pump fits into is fairly small. The pump impeller, to work properly, has to have a tight tolerance with the surrounding enclosure in the block to allow the pump to actually work and move coolant. Also, a bearing failure can occur in different ways, for example maybe there is movement in the z-axis along the impeller shaft allowing the impeller to hit the metal directly in front of it and not necessarily the metal around it . . . One other interesting note, for the first time since I've had the rebuilt engine installed, I heard the famous "startup rattle" yesterday. I think this could be further evidence of a water pump bearing starting to fail.

I've also thought this through and there are three additional scenarios that could potentially be causing the noise: 1) An oil pump problem, 2) a cracked piston skirt where part of the piston actually broke off and dropped into the oil pan or 3) a cracked/damaged timing guide knocking around inside the timing chain cover. As part of my diagnostics, I did an oil change to see if there would be any change in the engine noise and there was not. However, I did run the oil from that most recent oil change through a fine mesh screen (one used for straining automotive spray paint) to see if there were any noticeable metal or plastic bits in the oil, and there were none.

I'm open to recommendations on this, but I think my next step is to pull the front valve cover and see if there is noticeable play in the timing chain coming up from the water pump and to the bank 2 camshaft actuator.
 
At best, you could surmise issues with the guide/tensioner causing slack in the timing chain.  Shouldn't stretch this early, but could be.  The water pump being affected would be secondary to this scenario, not primary.  Regardless, if one or the other is the cause, in for a penny in for a pound.  Go in to replace WP, replace timing components.  Go in to replace timing components, replace WP.

If you are ok with pulling the VCs, I suppose you could tell if there is slack in the chains, whether from stretch or due to a faulty guide.

I would definitely make sure to use filters constructed similarly to the MC with relation to the ADBV to minimize the issue of oil starvation at startup.  An ester based full synthetic oil would not hurt either.  Beyond that, it is down to timing components I think.
 
So, I haven't been driving the Flex due to the unknown engine noise. I picked up a 2007 Lexus LS460 to drive in the meantime. However, I am back to trying to determine what could be wrong and found this video which clearly shows the same noise as my engine. They claim it is from a faulty timing chain tensioner, can anyone verify this?

https://www.youtube.com/watch?v=CVMj-zfJm5M
 
FoMoCoSHO - Thanks very much for the note you sent.

To provide everyone an update on the situation, I have concluded that the knocking noise I am hearing was not due to the water pump, but actually due to the cam phasers knocking at idle.  The fact that the noise only occurs once the engine starts to warm up (and the oil thins out) and also only at low RPMs (under around 1,000 rpm), are both very good indicators that the sound is actually from the cam phaser lock pin making noise while seated.  The noise goes away when slightly off idle. 

After watching and listening to lots of YouTube videos of cam phaser issues on different Ford engines, it's now fairly clear to me that this is the sound I've been hearing.  What I can't explain is why the Ford techs at my local dealer were unable to make that diagnosis since this is something they probably see (and hear) on a regular basis.
 
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