Aliis Chalmers B Engine Noise

Brian Burks

New User
My B has run reliably for many years with a Woods belly mower to cut my grass. The oil was neglected and now there is a thump/clunking noise coming from the engine. It still runs well, but I don"t want to worsen the problem by running it with this noise. Any suggestions on where to start?
 
Sounds like it could be a rod bearing or a main bearing,better drop the pan and pull the mains and rod caps before you cause more damage,.
 
Is the noise high or low, is it a tap or a rattle etc. Many places can make noise and you need to find if it is top or bottom. A water pump going bad can cause a noise or a lose crank pulley or any thing that moves or can be lose. Have you changed the oil?? If you did do you see a silver sort of look to it??
 
If you have not drained the oil you will not be likely to be able to see the silver look in the oil if it is there. Also how it the oil pressure on it???
 
If the noise was low in the engine why did you pull the head off?? Low noise means you pull the pan so you find the problem before doing things that could cost you more $$
 
The oil pan of those old tractor is a simple 14 or so bolts after draining the oil then you can reach up and feel the rods one by one to see if any are loose to the feel. Of course know this type of thing comes with years of working on engines and not all people have the feel for things
 
Make certain you mark the main and rod caps for position and direction before you remove them. I use an engraver. Mark the rod and rod cap and the main cap. If you already knew this...better safe than sorry. Rods kind of sound like someone knocking on a door, mains are usually a deeper noise. If the bearing spun in the housing that needs to be addressed too. Hope this helps. Gerard
 
Don't take very many knocks until the crankshaft needs ground. If I was he I'd get an engine stand, hang the engine on it with the pan up and then work my way down.
 

Could be just a Throw-out Bearing, or maybe a Wristpin..??

Even a loose Tappet can have a sound like a rod knocking sometimes..or maybe the (Main) Thrust-Bearing could have excessive clearance, letting the crank slip forward/Back too far.?

Why in the World didn't you try changing the oil..???
Ron..
 
It turns out the noise was being caused by a rod bearing. We tore the engine down. We took the crankshaft out to have it turned but it was already undersized. Any ideas on a good place to find a replacement?
 

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