Catalytic knock
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Cross-Country
Joined: Oct 2005
Posts: 91
Likes: 1
Catalytic knock
Good day!
My 2006 F150 5.4L Lariat 4x4 just developed an interesting noise...well, the noise has been around for about 3 months...anyways, I finally got around to getting into the noise and need some knowledge from the Ford community. The noise I am hearing sounds like a rod knock...it only happens when I start the motor for the first time in the morning. As stated, it really sounds like a rod knock from the bottom of the motor...so, I got my trusty 18 inch screw driver out, started the motor, got underneath the truck and started to do some detecting. From what I can ascertain, it sounds like the noise is coming from the passenger side catalytic converter?? I did not expect that...I surely thought I had a rod bearing going south on me...I listened to ever inch of that motor on the bottom and it is the loudest and strongest when I put the "stethoscope' up to the catalytic converter. It will only last about 3 mins from initial morning start...after that, no knocking noise. I put the computer to the motor and it says there is no issue with the cats (temps and O2bank2/sensor1/O2bank2/sensor2)) sensors are reading normal cat functions for the passenger side (actually, they read normal for both banks/sensor 1/2). soooo, my question is...has any one had this issue? While the "knock" goes away after the cats warm up, are my cats going the way of the dinosaur?
Thanks in advance...
My 2006 F150 5.4L Lariat 4x4 just developed an interesting noise...well, the noise has been around for about 3 months...anyways, I finally got around to getting into the noise and need some knowledge from the Ford community. The noise I am hearing sounds like a rod knock...it only happens when I start the motor for the first time in the morning. As stated, it really sounds like a rod knock from the bottom of the motor...so, I got my trusty 18 inch screw driver out, started the motor, got underneath the truck and started to do some detecting. From what I can ascertain, it sounds like the noise is coming from the passenger side catalytic converter?? I did not expect that...I surely thought I had a rod bearing going south on me...I listened to ever inch of that motor on the bottom and it is the loudest and strongest when I put the "stethoscope' up to the catalytic converter. It will only last about 3 mins from initial morning start...after that, no knocking noise. I put the computer to the motor and it says there is no issue with the cats (temps and O2bank2/sensor1/O2bank2/sensor2)) sensors are reading normal cat functions for the passenger side (actually, they read normal for both banks/sensor 1/2). soooo, my question is...has any one had this issue? While the "knock" goes away after the cats warm up, are my cats going the way of the dinosaur?
Thanks in advance...
Logistics Pro
Joined: Dec 2003
Posts: 3,776
Likes: 862
From: Foothills of NC
I had a 2003 Expedition with a 4.6 do that. It drove me crazy. It would come and go for no apparent reason. When knocking, it sounded like a rod was coming out in a drive thru. Mine was drivers side, front cat.
Never had an issue with the engine at all. I sold it that way a few years later. Very annoying though.
Never had an issue with the engine at all. I sold it that way a few years later. Very annoying though.
Fleet Mechanic
Joined: Dec 2003
Posts: 1,436
Likes: 117
From: Virginia
The media / brick inside the converter has come loose.
Once the engine runs enough, the force of the exhaust is likely wedging the piece so it doesn't move as much as it did at first.
I had to replace mine a few years back prior to Bid__-flation so the prices on these have doubled.
I bought a set of direct fit from Magnaflow.
They worked great & the truck ran great after.
https://www.magnaflow.com/collection...tic-converters
Once the engine runs enough, the force of the exhaust is likely wedging the piece so it doesn't move as much as it did at first.
I had to replace mine a few years back prior to Bid__-flation so the prices on these have doubled.
I bought a set of direct fit from Magnaflow.
They worked great & the truck ran great after.
https://www.magnaflow.com/collection...tic-converters
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