Engine Knock.....Remove Engine or Go at it from Underneath
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Engine Knock.....Remove Engine or Go at it from Underneath
I have a loud engine knock in my 51 flathead. It sound like a rod or maybe a wrist pin. It does not go away when I speed up the engine. I took the belts off the engine eliminating the fan, alternator, harmonic balancer and water pumps. The knock is still there. The engine runs good, it just suddenly developed a knock.
I am new to the flatheads and this is my first time to have to work on one. My question is should I pull the engine or attempt to find the problem from underneath by removing the oil pan. I feel like I can probably pull the engine faster than wrestling with the oil pan. Any experts care to chime in on this?
Thanks, Scott in Texas
I am new to the flatheads and this is my first time to have to work on one. My question is should I pull the engine or attempt to find the problem from underneath by removing the oil pan. I feel like I can probably pull the engine faster than wrestling with the oil pan. Any experts care to chime in on this?
Thanks, Scott in Texas
Fleet Owner
Joined: Jul 2004
Posts: 27,303
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From: NM
The pan takes less than an hour to pull, just jack the truck up by the frame, put it on jackstands, the front axle now won't be in the way. But what can you really do with it off? To fix it right you need it out, and may as well find out what shape everything else is in.
Welder User
Joined: Feb 2009
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From: northwest MT
Agree......it will be much easier to work on the engine if you pull it. My flattie had a minor knock but ran good.......ended up doing a full rebuild. Figured as long as I had it apart, might as well do it right.
Fleet Mechanic
Joined: Dec 2005
Posts: 1,603
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Not so fast (yet) I've heard funky knocks all of a sudden from a bad
fibre cam gear. Seeing your fans off 2 minutes to pull the timming cover
off, I know, It happened to me, sounded like something came undone in
the bottom end. Im going thru that as I speak cant get my distrubutor
out so 5 bolts dist/ cover and all easy...
fibre cam gear. Seeing your fans off 2 minutes to pull the timming cover
off, I know, It happened to me, sounded like something came undone in
the bottom end. Im going thru that as I speak cant get my distrubutor
out so 5 bolts dist/ cover and all easy...
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Knock
I've been thinking about the flywheel area. I just can't pin point the noise yet.
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Post Fiend
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Pull it out, tear it down and take lots of pic's.
Here is how to post pic's on FTE
https://www.ford-trucks.com/forums/1...ure-guide.html
Here is how to post pic's on FTE
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Found the Knock
After checking the compression and finding the #7 cylinder dead, I decided to remove the head and what I found was not good news.
It appears the valve seat disintegrated and pieces were being pounded against the head and piston.
Fortunately the cylinder wall appear to be clear from damage.
Now I will be pulling the engine and hope the block can be repaired with a new seat and valve job.
Scott in Texas
It appears the valve seat disintegrated and pieces were being pounded against the head and piston.
Fortunately the cylinder wall appear to be clear from damage.
Now I will be pulling the engine and hope the block can be repaired with a new seat and valve job.
Scott in Texas
Fleet Owner
Joined: Jul 2004
Posts: 27,303
Likes: 1,062
From: NM
I think you'll be fine, at the worst a new piston and a head (both cheap). Ask Harleymsn about it! 
Edit: you could have bent the rod, I guess. Are you planning to yank it now? Usually the cause of a seat popping out is overheating, either locally or overall. Any engine as old as these nearly always benefits from a thorough cleaning of the water jackets, perfect time if you have it out.
Edit: you could have bent the rod, I guess. Are you planning to yank it now? Usually the cause of a seat popping out is overheating, either locally or overall. Any engine as old as these nearly always benefits from a thorough cleaning of the water jackets, perfect time if you have it out.
Welder User
Joined: Feb 2009
Posts: 5,269
Likes: 50
From: northwest MT
That sucks. Take a close look at that cylinder and rod. I had this happen once on an OT engine(piece of hardware down the intake)......bent the rod and cracked the cylinder wall. Not pretty!
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