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Hello everyone I am new to this forum but I’ve been a reader for many here for many years. I own a 2008 Ford Expedition 4wd 5.4l as of recently I’ve been hearing some knocking noise coming from the engine usually only on start up and idle. in order to get rid of the knocking I have to turn the car off and start it up again and then the knocking goes away. Recently I got the check engine light and the codes were for my camshaft position sensors and I replaced both of them. I thought the issue would go away but this time it didn’t. The car did drive a lot smoother after replacing the camshaft and the check engine light went away and hasn’t returned at all.
Today while driving for a bit I parked at the supermarket and when I returned to my car I cranked it and once again the knocking noise, it also had a slight shake to it. Once again I turn the car off turn it back on and the knocking and shake is gone. The knocking is loud as well, it actually grows in loudness the longer you keep the engine running. This on and off method has been working for me but now at certain moments when I’m driving and everything seems fine I’ll stop at a red light and the knocking appears again very loud and it’s only when I press the gas the knocking stops and the car is smooth again.
I checked oil levels it’s perfect. I don’t believe it’s a misfire I had my issues with those and know how the car acts when misfiring. At the moment there is no check engine light and when I take it to the mechanic they say they will have to hear the noise as it happens but the car performs like it’s brand new off the lot when around mechanics. Has anyone else had this issue before I would hate to have someone keep taking stuff apart and replacing everything to find out it’s something super simple. I do have a video I captured at the supermarket parking lot where you can hear the sound it’s making it’s not super loud but imagine the sound you hear amplified to the max. Any help would be greatly appreciated. Thanks in advance.
thsnks for the reply so from what I posted it sounds like a cam phaser issue? I did just do some research and the cam phaser noise I hear sounds nothing like what I hear.
thanks for this again I did read up on the cam phaser issues. I just want to know does the cam phaser knocking happen continuously or as I described simply when the car has driven for a bit and after being warm? Please I’m really trying to narrow this down my mechanic couldn’t explain the issue to me but was quick to charge me $6,000. The truck runs smooth as butter as if I just bought it. The noise is not constant at all as I described above. Thanks
Thats how they sound once they go bad and I suggest you stop driving it untill you fix it because your running the risk of starving your heads of oil and ruin the cam journals and cam itself. The ones you probably heard are the ones that just started to go bad and normally they just tick.
...
I just want to know does the cam phaser knocking happen continuously or as I described simply when the car has driven for a bit and after being warm? ...
... my mechanic couldn’t explain the issue to me but was quick to charge me $6,000. The truck runs smooth as butter as if I just bought it. The noise is not constant at all as I described above. Thanks
Actually, it's all perfectly logical when analyzed against the mechanical construction and operational design of phasers. If you don't mind a _lengthy post_, I'll make a stab at it. (As for the mechanic, its a good economic maneuver on his part if he could charge you six thousand for about $2,000 worth of parts and labor.) Now on to the phasers.
As for the noise showing up after driving a bit --- First, its imperative to understand a little about how the phasers use oil 'flow' AND pressure, as well as some aspects of hydraulics. (keep in mind their is a "restrictor" in the oil passageway where the oil galley enters the heads.) Hydraulic 'Pressure' is reduced downstream from any restriction - and that effect is amplified by any leak point downstream of the restrictor (such as cam bearings, phasers, and particularly chain tensioners whose gaskets are prone to failure.
Inside the phaser, there are TWO things that are, by design, dependent on oil "PRESSURE", and one that depends more on oil "FLOW". 1). The spring loaded locking pin that LOCKS the phaser at base (zero retard), depends on pressure (and a very small amount of flow) to depress the spring on the locking pin down and UNLOCK the two halves of the phaser so it can adjust the cam (attached to the rear half) - thus changing cams angular relationship to the phaser gear mounted on the front half of phaser. 2.) The phaser has 'VANES' inside enclosed chambers that oil 'flow' moves back & forth inside the chambers to position the rear half of phaser to advance or retard the cam. (NOTE THAT: Oil 'pressure' inside the chambers must overcome rotational resistance that valve springs place on the CAM).
These mechanical features can be seen in this photo. The Locking Pin sets on and presses the spring down. The spring pushes the pin up into a hole in the top half. Oil into and out of the chambers on opposite sides of the vanes is routed through advance/retard passageways by the VCT Solenoid moving it spool valve by duty cycle pulses from the PCM.
As your engine wears, overall engine oil pressure degrades from bearing surface ware - which is amplified downstream of the restrictors (the sole supply to the lifters/rockers/phasers and chain tensioners). As the oil warms, it thins - resulting in more oil pressure degradation in the heads from worn bearing surfaces. This is aggravated even more by worn components downstream from the restritors (cam bearings/phaser vanes/chain tensioners). In other words, downstream from these restrictors in the heads, the oil pressure declines as the engine warms and oil thins (more and more as things age) - and this is exaggerated as compared to the lower end (crank / rod bearings) by the restrictor located in the head.
As oil pressure in the head decreases (due to age / normal bearing ware), it finally reaches a point where the pressure inside advance chambers can no longer HOLD the phaser vanes 'FIRMLY' against the advance end of the chamber. The rotational torque of the CAMSHAFT depressing valve springs - (two intake and one exhaust) results in a highly irregular rotational torque at ~150 hertz ((600 RPM/ 2 -cam/crank ratio)/2 banks. Usually only ONE Phaser is knocking). This irregular torque pattern causing vanes inside the phaser to 'SLAP' against the end of advance chambers. Secondly/alternatively: the locking pin SHOULD drop into it's hole, LOCKING the phaser at ZERO retard below a certain Oil pressure ((???? an unknown)) and thus phasers should be independent of oil pressure at idle until oil pressure rises above the point required to UNLOCK the pin. BUT - Wear in the locking pin can also produce play in that locking pin, resulting in IT making a similar noise, which would also be less while oil is cold and thicker.
Thirdly: In some cases, plastic pieces from broken chain guides clog oil pump pickup screen -- resulting in degraded oil pressure throughout the engine resulting in the same noise. It can occur when oil thins / or all the time resulting in randomness of the noise.
In my opinion, you're at the point where you need a phaser job - and might as well bite the bullet and do chains / guides / tensioners / phasers and all.
thanks so much for this detailed understanding one last thing I’m getting these codes
p0010 p0012 p0020 p0340 p0355 and the car starts up fine and looses power or dies when I put it in gear. There is also a terrible smell from underneath the truck tha
Originally Posted by F150Torqued
Actually, it's all perfectly logical when analyzed against the mechanical construction and operational design of phasers. If you don't mind a _lengthy post_, I'll make a stab at it. (As for the mechanic, its a good economic maneuver on his part if he could charge you six thousand for about $2,000 worth of parts and labor.) Now on to the phasers.
As for the noise showing up after driving a bit --- First, its imperative to understand a little about how the phasers use oil 'flow' AND pressure, as well as some aspects of hydraulics. (keep in mind their is a "restrictor" in the oil passageway where the oil galley enters the heads.) Hydraulic 'Pressure' is reduced downstream from any restriction - and that effect is amplified by any leak point downstream of the restrictor (such as cam bearings, phasers, and particularly chain tensioners whose gaskets are prone to failure.
Inside the phaser, there are TWO things that are, by design, dependent on oil "PRESSURE", and one that depends more on oil "FLOW". 1). The spring loaded locking pin that LOCKS the phaser at base (zero retard), depends on pressure (and a very small amount of flow) to depress the spring on the locking pin down and UNLOCK the two halves of the phaser so it can adjust the cam (attached to the rear half) - thus changing cams angular relationship to the phaser gear mounted on the front half of phaser. 2.) The phaser has 'VANES' inside enclosed chambers that oil 'flow' moves back & forth inside the chambers to position the rear half of phaser to advance or retard the cam. (NOTE THAT: Oil 'pressure' inside the chambers must overcome rotational resistance that valve springs place on the CAM).
These mechanical features can be seen in this photo. The Locking Pin sets on and presses the spring down. The spring pushes the pin up into a hole in the top half. Oil into and out of the chambers on opposite sides of the vanes is routed through advance/retard passageways by the VCT Solenoid moving it spool valve by duty cycle pulses from the PCM.
As your engine wears, overall engine oil pressure degrades from bearing surface ware - which is amplified downstream of the restrictors (the sole supply to the lifters/rockers/phasers and chain tensioners). As the oil warms, it thins - resulting in more oil pressure degradation in the heads from worn bearing surfaces. This is aggravated even more by worn components downstream from the restritors (cam bearings/phaser vanes/chain tensioners). In other words, downstream from these restrictors in the heads, the oil pressure declines as the engine warms and oil thins (more and more as things age) - and this is exaggerated as compared to the lower end (crank / rod bearings) by the restrictor located in the head.
As oil pressure in the head decreases (due to age / normal bearing ware), it finally reaches a point where the pressure inside advance chambers can no longer HOLD the phaser vanes 'FIRMLY' against the advance end of the chamber. The rotational torque of the CAMSHAFT depressing valve springs - (two intake and one exhaust) results in a highly irregular rotational torque at ~150 hertz ((600 RPM/ 2 -cam/crank ratio)/2 banks. Usually only ONE Phaser is knocking). This irregular torque pattern causing vanes inside the phaser to 'SLAP' against the end of advance chambers. Secondly/alternatively: the locking pin SHOULD drop into it's hole, LOCKING the phaser at ZERO retard below a certain Oil pressure ((???? an unknown)) and thus phasers should be independent of oil pressure at idle until oil pressure rises above the point required to UNLOCK the pin. BUT - Wear in the locking pin can also produce play in that locking pin, resulting in IT making a similar noise, which would also be less while oil is cold and thicker.
Thirdly: In some cases, plastic pieces from broken chain guides clog oil pump pickup screen -- resulting in degraded oil pressure throughout the engine resulting in the same noise. It can occur when oil thins / or all the time resulting in randomness of the noise.
In my opinion, you're at the point where you need a phaser job - and might as well bite the bullet and do chains / guides / tensioners / phasers and all.
The P0355 is pretty easy. Plug the wire back on the COP on cylinder # 5 and make sure the clip snaps good. That one will probably go away. And giggle / clean / plug / replug the connections to the Cam Position Sensor on Bank 1 to make sure you got good connections. That might fix the 340 and that could have some to do with the P0010 and 12 ----- but because of your original complaint about 'knocking', I sorta doubt it.
I'd try to narrow it down and address it -- misfires and phaser problems are hard on the CATS (which could be the source of the smell you mention).
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