Knocking ? w/video
Thread Starter
|
Junior User
Joined: Feb 2011
Posts: 60
Likes: 0
From: Winston Salem, NC
Knocking ? w/video
This is a 1983 Ford F150 w/4.9 there is an obvious knock that has started. I have been working out the kinks and I was trying to find some suggestions on what could be causing this. I only hear it at idle but I am half deaf. Sorry in advance as the quality is not to good but I was using my phone. Thanks.
YouTube - Knocking engine ?
YouTube - Knocking engine ?
Last edited by MartyRayII; Feb 15, 2011 at 12:24 AM. Reason: wrong link
Moderator
Joined: Dec 2007
Posts: 7,987
Likes: 104
From: Boise, Idaho
Sounds a little low pitched to be on the upper end (valve train, lifters, etc.)
I've been dealing with a knock in mine and trying to diagnose it, so I'll list the possibilities I've come across.
Exhaust leak. A hole or opening in the exhaust (manifold gasket, cracked manifold, etc) is causing a loud sound since the noise comes out of the hole before reaching the muffler.
Rod bearings or main bearings are worn, causing slop in the up and down motion of the pistons. If this is the case, you want to address it immediately by dropping the oil pan and checking/replacing them. If not, the slop (and noise) will amplify exponentially until it seizes or fails.
Wrist pin worn. The pin that holds the piston head onto the rod is worn, causing the piston head to knock up and down.
Piston slap. One or more (just sounds like one from the video) of the cylinders is out of round, causing the piston to wobble around as it moves up and down. You'll need to re-bore the cylinder(s) and get a new piston(s).
Another option is a bolt in the flywheel has come loose and is smacking every time it spins around.
Best of luck. Knocks aren't a fun thing to deal with or find. Hopefully yours is something simple and quick.
I've been dealing with a knock in mine and trying to diagnose it, so I'll list the possibilities I've come across.
Exhaust leak. A hole or opening in the exhaust (manifold gasket, cracked manifold, etc) is causing a loud sound since the noise comes out of the hole before reaching the muffler.
Rod bearings or main bearings are worn, causing slop in the up and down motion of the pistons. If this is the case, you want to address it immediately by dropping the oil pan and checking/replacing them. If not, the slop (and noise) will amplify exponentially until it seizes or fails.
Wrist pin worn. The pin that holds the piston head onto the rod is worn, causing the piston head to knock up and down.
Piston slap. One or more (just sounds like one from the video) of the cylinders is out of round, causing the piston to wobble around as it moves up and down. You'll need to re-bore the cylinder(s) and get a new piston(s).
Another option is a bolt in the flywheel has come loose and is smacking every time it spins around.
Best of luck. Knocks aren't a fun thing to deal with or find. Hopefully yours is something simple and quick.
FTE Legend
Joined: May 2008
Posts: 56,542
Likes: 0
From: In my own world
Trending Topics
Thread Starter
|
Junior User
Joined: Feb 2011
Posts: 60
Likes: 0
From: Winston Salem, NC
Yep as far as the gauge on the truck anyways its a little above mid way. Although keeping in mind your earlier post I went back out and checked it with the stethoscope again right at the harmonic balancer and as I slid back towards the 2 or 3 piston it was considerably louder. Am I correct at thinking that the timing chain is right up front? I am just winging it here really I can fix a lot of external crap but inside I am unexperienced. I really really need to get this taken care of if it is serious I can't afford another motor for sure. Or a rebuild just yet.
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
Top 10 Fords at 2026 Carlisle Ford Nationals
Joe Kucinski
3 Best / 3 Worst Parts of Modern Ford Ownership
Brett Foote
10 Amazing Upgrades That Solve Common Ford Truck Owner Headaches
Pouria Savadkouei
Every 2026 Ford Engine Explained
Brett Foote
10 Ugly Ford Trucks That We Still Kinda Love
Joe Kucinski
10 Things Every Truck Owner NEEDS (2026 Edition)
Michael S. Palmer
Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath
Verdad Gallardo
Top 10 Most Expensive Ford Trucks Ever Sold on Bring a Trailer
Joe Kucinski
2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)
Brett Foote
Moderator
Joined: Dec 2007
Posts: 7,987
Likes: 104
From: Boise, Idaho
The 300 is a direct gear to gear (no chain). If there's a problem with the timing gears, its because teeth broke or chipped.
However, if its getting louder as you move back, it is probably coming from the block.
If it is in the block, you'll need to disconnect the motor mounts, jack up the engine and remove the oil pan to diagnose further. From there, you can inspect the bearings, look for play in the rods, pistons, etc.
Maybe before you get that far, take it to a professional mechanic and ask him for a few moments of his time. They've probably heard all the sounds before, and can use a bit higher quality stethoscopes to pinpoint where the sound is coming from.
However, if its getting louder as you move back, it is probably coming from the block.
If it is in the block, you'll need to disconnect the motor mounts, jack up the engine and remove the oil pan to diagnose further. From there, you can inspect the bearings, look for play in the rods, pistons, etc.
Maybe before you get that far, take it to a professional mechanic and ask him for a few moments of his time. They've probably heard all the sounds before, and can use a bit higher quality stethoscopes to pinpoint where the sound is coming from.
Elder User
Joined: Oct 2008
Posts: 708
Likes: 1
Kill the cylinders one at a time by pulling the spark plug wire then listening with the scope to the sound change. Have the motor off when you do the actual wire disconnect/reconnect. Wrist pin/piston slap/rod bearing noise goes away when you take combustion pressure off a cylinder.
Be quick about this test if your truck has a cat. If it doesn't then take your time. Dumping lots of unburned fuel in the exhaust will damage a cat after a minute or so.
Be quick about this test if your truck has a cat. If it doesn't then take your time. Dumping lots of unburned fuel in the exhaust will damage a cat after a minute or so.
Thread Starter
|
Junior User
Joined: Feb 2011
Posts: 60
Likes: 0
From: Winston Salem, NC
Kill the cylinders one at a time by pulling the spark plug wire then listening with the scope to the sound change. Have the motor off when you do the actual wire disconnect/reconnect. Wrist pin/piston slap/rod bearing noise goes away when you take combustion pressure off a cylinder.
Be quick about this test if your truck has a cat. If it doesn't then take your time. Dumping lots of unburned fuel in the exhaust will damage a cat after a minute or so.
Be quick about this test if your truck has a cat. If it doesn't then take your time. Dumping lots of unburned fuel in the exhaust will damage a cat after a minute or so.
Thread
Thread Starter
Forum
Replies
Last Post
joe f350
Pre-Power Stroke Diesel (7.3L IDI & 6.9L)
24
Aug 29, 2011 08:32 AM
kane gray
6.4L Power Stroke Diesel
11
Aug 3, 2011 09:25 PM
MartyRayII
1980 - 1986 Bullnose F100, F150 & Larger F-Series Trucks
14
Feb 16, 2011 09:24 AM
CDF302v8
1980 - 1986 Bullnose F100, F150 & Larger F-Series Trucks
46
Jul 15, 2009 01:00 PM
