Unknown knock
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Unknown knock
Posting on several forums because I haven't diagnosed the problem yet and I'm at my wits end.
I know this is a F-150 forum but I'm scrambling to find a possible solution to my E-150 unknown knock.
1998 E-150 van 4.6l, 240k miles. Came home a week ago and parked truck in driveway. Next morning I started it up and got an immediate metal knock sounding like it was coming from the bell housing, sounded exactly like a cracked flexplate I've experienced before on a different vehicle. Used mechanics stethoscope checking both valve covers and heads, oil pan, transmission and catalytic converters. The noise was most prevalent in the bell housing but not as loud as when just listening to the engine with the naked ear. Good oil pressure both driving and idling (3/4 way up the analog gauge). Thought it was a cracked flexplate. Pulled trans and flexplate was fine but replaced with new along with a rebuilt torque converter. Noise remained. Removed the serpentine belt, noise remained. Prior to the new noise the only thing we've done recently is replace the muffler. Thought is might be a rod so changed the oil and added some motor honey, no change in the knocking. Pulled individual plug wires and noise remained each time. No oil in water or water in oil. Runs smooth for an engine with this mileage (no misses) and drives great. Showing no codes or pending codes on OBD II scanner after running it for half hour. Haven't seen anything like this when I search the web. I am perplexed as to why the knock started so abruptly, almost seems like it is being caused by an abrupt electrical or emissions related part failure. Any ideas??
I know this is a F-150 forum but I'm scrambling to find a possible solution to my E-150 unknown knock.
1998 E-150 van 4.6l, 240k miles. Came home a week ago and parked truck in driveway. Next morning I started it up and got an immediate metal knock sounding like it was coming from the bell housing, sounded exactly like a cracked flexplate I've experienced before on a different vehicle. Used mechanics stethoscope checking both valve covers and heads, oil pan, transmission and catalytic converters. The noise was most prevalent in the bell housing but not as loud as when just listening to the engine with the naked ear. Good oil pressure both driving and idling (3/4 way up the analog gauge). Thought it was a cracked flexplate. Pulled trans and flexplate was fine but replaced with new along with a rebuilt torque converter. Noise remained. Removed the serpentine belt, noise remained. Prior to the new noise the only thing we've done recently is replace the muffler. Thought is might be a rod so changed the oil and added some motor honey, no change in the knocking. Pulled individual plug wires and noise remained each time. No oil in water or water in oil. Runs smooth for an engine with this mileage (no misses) and drives great. Showing no codes or pending codes on OBD II scanner after running it for half hour. Haven't seen anything like this when I search the web. I am perplexed as to why the knock started so abruptly, almost seems like it is being caused by an abrupt electrical or emissions related part failure. Any ideas??
More Turbo
Joined: Oct 2019
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Going to ask if you checked the dust cover and made sure it was not bent in and letting the 4 nuts on the torque converter hit it or if the trans motor mount had broken letting it slap.
Had a sound come from my F150 and the pipe coming from the Cats to the muffler the clamp was taping against the trans crossover mount. The new muffler mount was longer and let the pipe drop down a little and it broke a hanging wield mount that tapped. Like you, I had a fun time finding it.
Had a sound come from my F150 and the pipe coming from the Cats to the muffler the clamp was taping against the trans crossover mount. The new muffler mount was longer and let the pipe drop down a little and it broke a hanging wield mount that tapped. Like you, I had a fun time finding it.
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Unknown knock
Yes I removed the transmission inspection plate and started the engine. No knock and no observed wobbling of the flexplate/torque converter. We replaced the transmission mount because we broke one of the bolts affixing it to the crossmember. The noise definitely is connected to the engine rpm, not just a random noise. Thanks for the input, I'm grasping at straws to figure this out.
More Turbo
Joined: Sep 2017
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"The noise definitely is connected to the engine rpm, not just a random noise. "
Sounds like an internal engine issue more commonly referred to as "Engine knock". Engine knock can be caused by many different things. I won't try to type them all here.
Google for Engine knock causes and there are numerous articles suggesting ways of narrowing down the source. The alternative is take it to a shop and have them listen and diagnose, because we can't hear the noise.
....could just be a bad knock sensor, if there is one on that engine.
Sounds like an internal engine issue more commonly referred to as "Engine knock". Engine knock can be caused by many different things. I won't try to type them all here.
Google for Engine knock causes and there are numerous articles suggesting ways of narrowing down the source. The alternative is take it to a shop and have them listen and diagnose, because we can't hear the noise.
....could just be a bad knock sensor, if there is one on that engine.
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When I put my stethoscope up to the oil pan I don't hear the knock so I'm discounting that it is a rod or main bearing, Not saying it couldn't be but nothing in my troubleshooting would suggest that. I've thought about a faulty knock sensor but wouldn't that through a code? I'm hoping that it isn't because from what I can find on the internet it is located under the intake manifold and with the location of the engine in this van I don't even want to try to remove the intake. I'm hoping that the rain will clear out tomorrow so I can work on this some more. Thanks
More Turbo
Joined: Sep 2017
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Yes, a faulty knock sensor should throw a code. If there is none, then that is likely not the problem. From your description you've done a thorough checking. It may take a high end scanner to help diagnose the problem.
More Turbo
Joined: Oct 2019
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Yes I removed the transmission inspection plate and started the engine. No knock and no observed wobbling of the flexplate/torque converter. We replaced the transmission mount because we broke one of the bolts affixing it to the cross member. The noise definitely is connected to the engine rpm, not just random noise. Thanks for the input, I'm grasping at straws to figure this out.
The reason being I have seen those slap the bell housing after coming loose on top from their hold down. They come down just to the right side of the trans and some people confuse them with an AC drain. Yes, they will sound like something is hitting the bell housing or the engine has something wrong with it.
Want to clarify this? I am thanking you mean no knock after removing and looking at that from the flexplate, torque converter.
No knock and no observed wobbling of the flexplate/torque converter.
You do know it takes two bolts to hold the transmission to the mount and if you lose one or broken one off it lets the trans twist a little with the torque of the engine and will cause problems sooner than later.
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Fleet Mechanic
Joined: Jul 2019
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The oil pressure gauge is a fake gauge. Where it reads is nearly irrelevant as “good” pressure means 7 PSI or more. So, don’t discount internal engine issues just yet as you don’t have a clue what the actual pressure is.
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Laughing Gas
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From: Minnesota
Check for the noise at the small cats. that are right after the exhaust manifold. I had a 5.4 in a 2002 that developed a knock after a muffler change. I did a lot of bouncing around on the internet and found that the knocking noise from the first cat(s) was such an issue, Ford had a TSB where they actually installed a wrap kit over the cat. to muffle the noise. My 2003 has had that "knock for 65,000 miles...never any better...never any worse. 5.4 motor. My own opinion on it is piston slap.
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