351 noise identification
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Tuned
Joined: Apr 2023
Posts: 468
Likes: 67
From: Near SLC Utah
351 noise identification
This video is a week or so old, but this is my 88 351w, I have no idea why it is making this noise, I thought it was rod knock initially, but all the rods and wrist pins don't have any play in them.
I am pulling my hair out trying to find out what this noise is any help would be greatly appreciated.
I am pulling my hair out trying to find out what this noise is any help would be greatly appreciated.
Butt-Head
Joined: Apr 2004
Posts: 9,432
Likes: 2,920
From: Reed Point, MT
It's a made-up term that some people use. The full misnomer is "predetonation" which has no meaning whatsoever and is a blending of the words "preignition" and "detonation"; both of which ARE actual terms and conditions but are completely different in how each is created. I guess "predetonation" is a way to cover both scenarios without actually knowing what is happening.
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Tuned
Joined: Apr 2023
Posts: 468
Likes: 67
From: Near SLC Utah
Yeah I am leaning away from it, considering how the spark plugs are new and its only one cylinder doing it, and I used fresh gas, the timing was correct and all the spark plugs are matched up per the dizzy.
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Tuned
Joined: Apr 2023
Posts: 468
Likes: 67
From: Near SLC Utah
Do you guys think it could be rocker arm, it seems way to loud to be a lifter to me. The rocker arms were very well broken in, I could barely feel the oil journals with my fingernail, I will take off the valve covers and see what is going on under those things.
Laughing Gas
Joined: Jul 2023
Posts: 991
Likes: 317
Could very well be. Only other thought I had was maybe you had a valve get smashed into the piston. That's my only guess at this point. Good luck!
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Thread Starter
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Tuned
Joined: Apr 2023
Posts: 468
Likes: 67
From: Near SLC Utah
Alright I pulled the covers, some of them had a little play in them, maybe a 1/8th inch, I don't really know if its causing the problem. I figured I will just replace them, I am gonna look inside the pistons tomorrow and see if there is evidence of the valves hitting the piston.
Laughing Gas
Joined: Jul 2023
Posts: 991
Likes: 317
Alright I pulled the covers, some of them had a little play in them, maybe a 1/8th inch, I don't really know if its causing the problem. I figured I will just replace them, I am gonna look inside the pistons tomorrow and see if there is evidence of the valves hitting the piston.
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Tuned
Joined: Apr 2023
Posts: 468
Likes: 67
From: Near SLC Utah
UPDATE:
I pulled all the plugs today and used a bore scope and there is no evidence of the valves hitting the piston.
I also got a socket and a extension on the connecting rods and with some force I got some play out of all of them not a lot but enough to where I could feel and hear it, I am going to get a re ring kit and going get new bearings and just rebuild it unless I can find a rebuilt block soon, I unfortunately need the truck ASAP and this is the fastest way as of right now.
I pulled all the plugs today and used a bore scope and there is no evidence of the valves hitting the piston.
I also got a socket and a extension on the connecting rods and with some force I got some play out of all of them not a lot but enough to where I could feel and hear it, I am going to get a re ring kit and going get new bearings and just rebuild it unless I can find a rebuilt block soon, I unfortunately need the truck ASAP and this is the fastest way as of right now.
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Tuned
Joined: Apr 2023
Posts: 468
Likes: 67
From: Near SLC Utah
UPDATE:
Never gonna believe this, somehow a sheet metal screw ended up in cylinder 7. Upon further diagnosis all the bearings are just copper, no overplate, the block was pitted, and so worn the machine shop had to bore it out to 30 over and had to sleeve the one cylinder that was pitted, I knew the block was worn, but I didn't know it was that bad.
Never gonna believe this, somehow a sheet metal screw ended up in cylinder 7. Upon further diagnosis all the bearings are just copper, no overplate, the block was pitted, and so worn the machine shop had to bore it out to 30 over and had to sleeve the one cylinder that was pitted, I knew the block was worn, but I didn't know it was that bad.
Laughing Gas
Joined: Jul 2023
Posts: 991
Likes: 317
UPDATE:
Never gonna believe this, somehow a sheet metal screw ended up in cylinder 7. Upon further diagnosis all the bearings are just copper, no overplate, the block was pitted, and so worn the machine shop had to bore it out to 30 over and had to sleeve the one cylinder that was pitted, I knew the block was worn, but I didn't know it was that bad.
Never gonna believe this, somehow a sheet metal screw ended up in cylinder 7. Upon further diagnosis all the bearings are just copper, no overplate, the block was pitted, and so worn the machine shop had to bore it out to 30 over and had to sleeve the one cylinder that was pitted, I knew the block was worn, but I didn't know it was that bad.
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