149 possible engine knock

[Mr Bob]

Have a pretty rough 149 that I bought last winter. Rebuilt the carb, set the time using static method, had the s/g rebuilt and now it starts and runs decent. As you rev the engine I can hear a knocking noise that I believe is coming from the engine. Do not hear the noise at idle, but my hearing is not the best. When the engine is put under load as in going up hill with mower running, I can no longer hear the noise. I know it is difficult to diagnose a noise not being able to hear it but thought some one may have encountered the same symptoms. Any help will be appreciated. Sorry for the long post. I check the forum every day and usually learn something new. A lot of smart cc people here.
Bob

[cub123]

Most of the time it's the front PTO clutch disc knocking, can't say for sure, but it's the first thing I would check.

[Cub Cadet 123]

Of course it could be a lot of different things making the knocking noise, but for my 149 it was the balance gears were in several pieces in the oil pan. I removed mine and did not replace them, as per advice from many people. The engine shakes just a little bit more now, but nothing that I am going to complain about. I hope that is all that is up with your 149. Keep us posted.

Cub Cadet 123

[J-Mech]

Originally Posted by cub123

Most of the time it's the front PTO clutch disc knocking, can't say for sure, but it's the first thing I would check.

I agree with Ben. If it doesn't make the noise with the PTO on, it's probably the PTO clutch.

[clint]

I had a 1450 that made a knocking sound similar to what you describe I found by removing the head that the piston had wore and was rattling inside the bore. I hope it's something simple like the pto on your 149, I also have a 149 a fine machine

[Yosemite Sam]

It could be any number of things, rule of thumb would be that a rod in an engine will knock louder when under a load.

If you don't find the problem on the outside of the engine, I do believe that I would be checking (and removing) the balance gears if they are still in there before they escape on their own.

Good luck.

[TheSaturnV]

Agree with these fellers, check the external stuff out first and then move to the internals. A big second on looking into the balance gears. The ones in my 14hp were just kind of sagging on their spindle....it's a wonder they hadn't already grenaded the motor.

[cadzag72]

on my 72, the pto clutch disk "teeth" (the pieces that stick out into the basket pulley to drive it) are rather worn down and the anti-rattle springs are all long since departed. that creates my knocking sound. to test, with the engine not running, engage the PTO and try turning the PTO pulley by hand. if you get a good amount of "wiggle room," that could be your knocking sound.

[sawdustdad]

Drain some oil, and look carefully to see if you have any aluminum powder/flakes in it. Put a couple drops on a paper towel and let it sit for a while. If you see metal powder, it's likely the piston is worn and you're looking at a rebuild.

[Mr Bob]

Thanks for all the input. Let me add to my original post. The knock is still there when pto is engaged but not as loud when the engine requires more power like going uphill. Did the old timers screw driver test on it today. I could hear the knock with the tip of screw driver on non engaged pto and screw driver handle to my ear. Put the screw driver several places on the engine and the loudest sound was with the screw driver on the exhaust fins as it comes out of the block. Could a blown head gasket cause this or a valve adjusted too loose? Tomorrow I will try to check some of the things that were suggested. Thanks again for all the help and support.

Bob