Farmall 706 Gas Rod Noise?

Matt Tieken · May 28, 2013

OK, the 706 starts great, runs great and so far, bush hogs great. There is a little valve noise, so I got a set of feeler gauges to adjust the valves.

I am not sure I am hearing things, but after I work it for a while, and it is good and warmed up, After I pull it around to the barn and put it in neutral, it sort of sounds like a rod is knocking.

If I put the engine under any load, like putting it in gear and moving, the knock goes away until I push in the clutch. Does this sound right?

If it is a rod, it isn't the end of the world, but I would like to catch it before it lets loose. If it isn't a rod, I am trying to think of what it might be.

Thanks for the input.

notjustair · May 28, 2013

Every rod issue I have had was much worse under load. Don't think it is a rod.

Allan in NE · May 28, 2013

Grease the throw out bearing and see what happens.

Allan

Bill in IL · May 28, 2013

I get a similar noise from my gas farmall 400. Like you say is only at idle. Have no idea what it is.

Matt Tieken · May 28, 2013

OK, that is good to hear. I will be doing all the PM I can stand this week since my wife will be having her best friend in town from California.

I will see if any of that helps.

Thanks guys.

Anonymous-0 · May 28, 2013

Unlikely it's a rod knock, but you could remove the plug
wires one at a time. If the knock goes away with a given
wire that's not a good sign.

Glenn

Jerry Hewes · May 28, 2013

I run an M, 300 and 400. My neighbor has a 656. I do all the service work. All of these tractors will "knock" at very low idle speeds. Never had a problem. Nothing evident on overhaul. I suspect slap of the piston skirt against the sleve with particular vibrations or oscillations in RPM due to being an internal combustion engine and/or imprecise ignition timing aka detonation.

Matt Tieken · May 28, 2013

I am familiar with piston slap. I just never thought about that being the possible case on these engines.

Thanks for all the tips. I will be trying all of them.

todd hamilton · May 28, 2013

Don't set the valves too tight, like an old
straight six Chevy a little tappet noise is
normal, go by spec in book not by the sound.
Are you running 30w low ash oil in it?

Matt Tieken · May 28, 2013

In the manual it says to set the valves to .027". I have a .026 and .028" feeler gauge. I will probably set them on the .028" side for now.

I will be changing the oil this week too. I haven't thought about what weight of oil I am going to run, but I do know to run low ash oil. Can I get that at NAPA or do I have to track down an IH dealer?

Janicholson · May 28, 2013

Put IH low ash oil in it. Less than .5% ash is the spec. Tough to find in other oils but possible. Jim

Owen Aaland · May 29, 2013

(quoted from post at 15:18:59 05/28/13) Every rod issue I have had was much worse under load. Don't think it is a rod.

Generally rod bearings will get quieter under load. Main bearings will knock louder under load.

RedRoundhead · May 29, 2013

Once in a great while, a rocker, or its shaft will
crack or break, which sounds alot like a connecting
rod knock.

Just a thought; neighbor had a diesel that did that
on him once. Kinda odd.

Good luck.

Farmall 706 Gas Rod Noise?

Matt Tieken

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notjustair

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Allan in NE

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Bill in IL

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Matt Tieken

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Anonymous-0

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Jerry Hewes

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Matt Tieken

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todd hamilton

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Matt Tieken

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Janicholson

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Owen Aaland

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RedRoundhead

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