Help identifying a knocking noise coming from my 1985 FJ60 2F engine please

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It almost sounds like a leak in your air pump system. I’m assuming the noise goes faster if the engine rpm increases?
Did it start all of a sudden or has it been growing louder?

it has a real pumping sound to it.

you might try one by one pulling the spark plug wires. And see if any one cylinder quiets things down.
 
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It almost sounds like a leak in your air pump system. I’m assuming the noise goes faster if the engine rpm increases?
Did it start all of a sudden or has it been growing louder?

it has a real pumping sound to it.

you might try one by one pulling the spark plug wires. And see if any one cylinder quiets things down.
Had it since I got it but it might have been getting louder recently - hard to tell. Yes it gets faster with RPM

Thanks - I'll try pulling each plug and seeing what happens
 
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Had it since I got it but it might have been getting louder recently - hard to tell. Yes it gets faster with RPM

Thanks - I'll try pulling each plug and seeing what happens
Pull one plug wire at a time with all others still connected, then reconnect and move on to the next. If you do this and all of a sudden the noise gets a lot quieter you've likely found the problem cylinder and also likely confirmed its a bearing issue. Basically without the spark there is no power generating event on that cylinder and the thrust force is removed. There is obviously still movement....so if there is say a hole in your block the noise wont go away but if there is a bearing issue it might get quieter.
 

g-man

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It almost sounds like a leak in your air pump system. I’m assuming the noise goes faster if the engine rpm increases?
Did it start all of a sudden or has it been growing louder?

it has a real pumping sound to it.
yeah it does sound like air pumping but he has no air pump.

With the engine cold, start it and run you hands all around the block, exhaust and cylinder head and see if you can feel air pushing out anywhere. Esp. check where the EGR was once connected to the exhaust. Also feel around where the intake and exhaust mount to the cylinder head.

Does this engine make power? Will it run up a hill or does it lose power? This is a poor mans compression test. Alternately you could get a compression gauge for around $20 at walmart or any parts store and check each cylinder for compression.
 
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While it’s running you can have someone cover the end of the exhaust pipe with a towel and recommended a good heavy glove as the moisture in the exhaust can burn you quite quickly. Basically try to block the tailpipe for a second and see if the noise changes or if any leaks become more obvious
 
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Pull one plug wire at a time with all others still connected, then reconnect and move on to the next. If you do this and all of a sudden the noise gets a lot quieter you've likely found the problem cylinder and also likely confirmed its a bearing issue. Basically without the spark there is no power generating event on that cylinder and the thrust force is removed. There is obviously still movement....so if there is say a hole in your block the noise wont go away but if there is a bearing issue it might get quieter.
So I started pulling plugs, at one point it stalled, restarted and pulled the choke out a little more, pulled a couple more, could hear the RPM dipping before I reconnected. Then all by itself it just seemed to go away. No noise. restarted to see if it came back. can't hear a thing. Letting it cool now to see if it comes back
 
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So I started pulling plugs, at one point it stalled, restarted and pulled the choke out a little more, pulled a couple more, could hear the RPM dipping before I reconnected. Then all by itself it just seemed to go away. No noise. restarted to see if it came back. can't hear a thing. Letting it cool now to see if it comes back
Any idea which plug was disconnected when it got quiet. Or did disconnecting one plug cause a stall where another plug was just a rough idle? And just to confirm you’ve only got one plug disconnect at a time so you are always running on 5 cyls right?
 

OSS

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If pulling and replacing all the plug wires got rid of the sound, the problem was one spark plug wasn't firing. The engine was running on 5 cylinders.
Since the bad sound was coming out of the exhaust pipe too when it was happening- that points to a misfire.
When the 2F has a dead cylinder due to no compression or spark, it can set up a rhythmic racket.
 
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If pulling and replacing all the plug wires got rid of the sound, the problem was one spark plug wasn't firing. The engine was running on 5 cylinders.
Since the bad sound was coming out of the exhaust pipe too when it was happening- that poaunts to a misfire.
When the 2F has a dead cylinder due to no compression or spark, it can set up a rhythmic racket.
found a bad connection and did a half assed fix on it. wiggling the wires makes it go away, I ordered a new set - thanks!

fingers crossed this makes it go away and I have one less problem..
 

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