M602 Engine Noise

cleddy · May 27, 2013

I posted before how my M602 developed engine and it sounded like a clicking noise toward mid engine or the top but my first suspect is rod bearings. Drained the oil and it looked fairly normal & black and put new in. Still making the noise. Someone suggested maybe a lifter or something in regard to the valves was wrong but they appear to be working okay. With new oil pressure is still 30-40 and rocker arm shafts all have good oil dripping out. I'm getting ready to tear into it but want to eleminate any possible simple things. I suspose dropping the oil pan and looking at the bearings is the next reasonable step but has anyone ever had trouble with lifters and valves making noise and needing repair? Maybe a compression test is in order but tractor starts good and runs smooth except for the strange noise. Wish I could come up with a different & fresh engine??
Cleddy

casecollectorsc · May 27, 2013

Rod bearings would make a knocking noise. Did you set the intake and exhaust valve clearance?? Put a large screwdriver to the block with your ear on the handle and see if you can isolate the noise closer.

Cliff Nelson · May 27, 2013

Check the rocker arm stands carefully. My M-5 was assembled incorrectly before I got it and one of the rocker arm stands was broken where the short bolt holds it to the head. The nut on the long bolt backed off and allowed the stand to raise up with the pressure from the push rods. That made a clicking noise that was hard to find. Everything sat in place with the engine off so it looked ok. Good luck in finding your problem.

Alan K · May 28, 2013

I think I had read one time in a ZT operators manual (I may have to look again to make sure) if you short out each spark plug, one at a time, if the noise disappears it would be a rod bearing, (could be a piston pin as well I would imagine) if the noise doesnt disappear it would be a main bearing, but didnt the ZTs have roller bearings on a couple of the mains? Ill have to find the book and check it to make sure how it was worded.

MMDEL · May 28, 2013

Clicking don't sound like any Brg's I had an MM engine once with a loose clicking noise, and it was a bent push rod striking the side of the head. Tappets were adjusted properly. Probably why the guy got rid of it.
MMDEL

Curtis Rink · May 29, 2013

I had a similar sound once but it would only occur after working the engine for a few minutes. The piston would warm up and expand and hit the head. I had put too thin a gasket between the blocks and the crankcase. Expected it was a lifter or rod bearing according to the sound.

cleddy · May 29, 2013

I'm still at a loss on the noise. I've tried all the suggested things and still have nothing definite. Exhaust gasket is bad on #3 cylinder and engine is so noisy it is hard to tell just where the noise is. It does seem to be by #2 & #3 so that where I'll keep looking. The Noise may be more of a knock than a click and it does sound like a fan blade hitting something but it is not anywhere near that area. I'm going to pull the manifold off and see if something off the top flange may of dropped in there and is knocking around. Push rods are straight and valves seem to be working fine. cleddy

Whiskey Bent · May 29, 2013

Carbon?

Anonymous-0 · May 30, 2013

What would piston slap sound like? I have a M5 that I had the blocks bored and it has a little knock at idle. Mechanic thought it might have been over bored on one hole.

MMDEL · May 30, 2013

Better fix that leaky exhaust first before you waste time tearing down something unnecessarily. A leaky exhaust can have a knocking effect to the sound.
MMDEL

Anonymous-0 · May 30, 2013

yeh I agree ...first things first...had a G1000 that sounded like all heck was about to break loose simply a cracked exh manifold.

cleddy · May 31, 2013

Mystery sound is found. Number 4 cylinder seemed to be closest to problem and back rod bearing is loose and spun around. I was able to feel the wiggle through the oil filter opening and now the oil pan is off crankshaft journal is pretty well scored.

Coolant is a steady drip out of back of water pump so that most probably had a lot to do with the failure. I wonder how that back bearing gets lubricated since my oil pressure was good even with it flopping around back there.

Thanks for all the help and now it is time to get the check book out.
Cleddy

M602 Engine Noise

cleddy

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casecollectorsc

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Cliff Nelson

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Alan K

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MMDEL

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Curtis Rink

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cleddy

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Whiskey Bent

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Anonymous-0

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MMDEL

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Anonymous-0

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cleddy

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