M with knock

   / M with knock #1  

remchuk

New member
Joined
Jul 5, 2011
Messages
13
Tractor
case ih 245
My boy has a late '40's M that knocks only after it's warmed up. We do the 'listen through screwdriver' test and I hear the knock above and below the side covers (louder below) on #3.

I'm curious if it might be a wristpin and not the rod bearing? When I pull the plug wire for #3, the knock goes away.

What ya all think?

Thanks
 
   / M with knock #2  
Is this an M John Deere or an M Farmall? I like to visualize what's knocking. :)
 
   / M with knock #3  
Never mind. The John Deere wouldn't have had a #3 so, it must be a Farmall. Now don't I feel foolish?:D
 
   / M with knock
  • Thread Starter
#4  
Yup, IH. Not a Super, just a plain M (which is still pretty super in my family's opinion).
 
   / M with knock #5  
My M had a bad clutch. I split the tractor and replaced it, the throw out bearing seemed good so I didn't replace it. BIG MISTAKE. I felt foolish that time too.
 
   / M with knock
  • Thread Starter
#6  
Replaced the rod bearing and the knock still comes back after the engine warms up. Using SAE 30 oil.
I'm gonna put a master oil guage on it and see if there is good pressure.
What ya think the odds are of it being a crank bearing?

We don't have time or space to rebuild before hay time, so I'm just a little shy of desperate.
 
   / M with knock #7  
roll em out for a looksee.. if it's bad enough for a knock.. you'll see it on the bearing.. heck.. if it's been that way long enough.. might even see it on the cap.. at least it hasn't spun one probably.
 
   / M with knock
  • Thread Starter
#8  
Do I have to drop the crank to remove the center main? Is there a simple trick to get the top bearing out without pulling all three main caps?

I retested the "pull the spark plug wire method" and the knock remains. Last time I did it, I didn't rev the engine enough to get the knock back. So now I REALLY think it's the center main bearing.

I'm also gonna go ahead and refresh the oil pump while the pan is off.

Any other ideas to check while the pan is off?
 
   / M with knock #9  
You wont have to pull the crank but you probaly will have to slightly loosen all the mains to push old one out and new one in. I use a piece of flexible plastic to roll out bearings without scratching the crank.
 
   / M with knock #10  
ditto that...
 
 
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