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NAA Knocking Update

Michael Lacey An update to my previous thread a couple of weeks ago - recall the NAA was consistenly knocking. This weekend my father and I put a new air intake/cleaner assembly on. the knocking noise is almost 100% gone!!!

Explain that one!? Apparentlly a new set of lungs makes a world of a difference. the mesh filters were pretty well clogged up.

Just wanted to send an update. I think the bearings are still worn and will need replaced, but it was such a relief to hear it idle and run like it should.

thanks again guys.

Jim Loveridge Thanks for the update. I wonder if the restriction during the intake stroke causes the loose rod bearings to knock.
Michael Lacey Jim, may be the case. God only knows what crawls in and makes these things their home. When i changed the oil cup a few years back I was amazed at how many leaves and debris were in it.
I may consider changing the exhaust - especially if your theory is correct. I'm sure that's restrictive as well.

Anyone know where you can buy stainless steel exhaust? Everything i've seen is aluminum.

Bob G I think I would drop the pan and take a look ASAP. Change the bearing before they do any damage. You may get by just slipping in new bearing shells of the same size. Let it go too long and you may have to have the crank turned down.
Michael Lacey Jim, what are you suggesting? Remove the oil pan and try to wiggle them from below to check for tightness? I'd have to read up on it, but i dont believe you can get access to all of the bearings from underneath. I would think just the lower portion of the ones that surround the piston arm. Aren't there ones on the top half as well?
Bob G I would drop the pan and check the clearances with plastagage. you can get it at any auto parts tore. it comes in several sizes. I would do a google seach on using it. you should find some very good information. It sounds like you do not have a service manual. before you go any further, I would suggest you get one. It will pay for itself in no time. The connecting rod is the part that runs from the crank to the piston. the bearings have an upper and lower shell. they are matched sets and are to be replaced together. they come in several sizes depending on the dimension of the journals on the crank shaft.

Like I said get the manual and study it before you drop the pan. You want to know what you are doing before you start tearing it apart or you will have a pile of scrap iron in no time.
Good luck

D. M.
My NAA starts up and runs fine but clatters when you go to shut it down. Also, it will run for about 15 minutes at 50 psi oil and then the oil pressure drops and the tractor will lose power. . The oil was changed and a snap ring was found in the oil pan. Rod bearings were replaced at that time but the noise persists when throttling down. I presume the oil is getting hot and leaking somewhere causing the pressure drop but I haven't noticed any smoking out of the exhaust. Appreciate any ideas of where to start looking next.

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