IH 300U Engine Noise/Knock

[Dell]

All original. Starts easy, runs smooth no smoke. I use it for snow plowing.
Last couple weeks it has developed a front lower engine noise/knock when under load.
When pushing easy it is smooth and quiet. As soon as it starts pushing hard a loose noise comes from lower right front of engine. It is a definite knock but with a slight ring to it. It is not upper tappet rattle. Sounds like one cylinder to me but I am not a internal mechanic. I changed the oil and filter and added a half qt. Lucas. It quieted some but is now back to where it was before the oil change.
What is it and is it ok to drive it under no load.

[Gary Dotson]

By your description, it could very well be a connecting rod knock, caused by a worn rod bearing. Once they get loose enough for an audible knock, the damage can increase pretty quickly. You really should look into it as soon as possible.

[SONNY]

Ditto on what Gary said!!! sure sounds like rod about to go thru the side of the block!!!! thanks; sonny

[Dell]

Thanks for the responses. Going to have to leave it set till I can pull the pan.
Thanks,
Dell

[John *.?-!.* cub owner]

Might also want to pull the head and check for carbon build up on the pistons or in the head, that can cause similar problems.