D4 7U pony motor knock.

The pony is warning you!

Two things I would check before the next startup. Both would be after taking the heads off the pony. Remember to drain the main engine cooling system before popping the heads off.

I think it's most likely you have a wrist pin bushing or a piston that is failing. Should be able to see some marks on the top of the piston that's affected.

It could also be the connecting rod bearing, but I doubt it would still be running if it was that. I do have an OLD small block Chevy that when it was new, used to knock about 3 times when first started in the morning. I think they came up with the oil filter anti-drainback valve and the new style filter cured it. Hasn't knocked since the mid '90s. I doubt a Caterpillar pony motor would live long with that kind of clearance.

I can't help with actually fixing it, but you might try cranking it 10 seconds with the ignition off to get the oil moving before it fires up.

Check the throttle linkage. Probably set up incorrectly to not let the governor close the throttle.

[size=3]I think CC is onto the correct cause. Any loud knock cannot be good news. Sounds more like a cracked piston that when it gets heated expands and doesn't rattle as much. The early small block V-8 Chevy engines were notorious for cracked piston skirts and rattled when cold but calmed down when warmed up. The lack of noise when warm is only covering up a more serious problem that can be very expensive to fix if not fixed now.

Let us know what you find out. [/size]

For the idle, check that the tang on the throttle rod is behind the throttle arm boss. The rod pulls the throttle closed against the governor spring. If yours is not doing this, then you won't be able to idle it down. Starting it at idle is important for longevity because it enables the oil to circulate/splash to fill the clearances before you run at high speed.
Losing 3oz per run is 10% of your total oil volume (pony takes 1qt/32oz). Make sure you fill up to the mark before every start. This will have the side effect of keeping your oil generally newer because you're leaking the "old" stuff out.

I did get out today and got the hood off of the 7U for a look down onto the carb. The throttle tab/tang is on the outside of the governor linkage. As you push the throttle in the tab moves and lets the governor arm move out away from the tractor. The governor rod is hooked to the carb butterfly. The shaft that holds the butterfly moves when you push on the governor arm. So with that said, next is to get the air breather off and look and see what is wrong. Screws out of butterfly or something broken. Probably end up pulling the carb off for repairs. If I remove the air breather and fuel tank can I get it off the engine? This is an outside project, no shop so just so much time during the day to work on it. Thanks.

I did get out today and got the hood off of the 7U for a look down onto the carb. The throttle tab/tang is on the outside of the governor linkage. As you push the throttle in the tab moves and lets the governor arm move out away from the tractor. The governor rod is hooked to the carb butterfly. The shaft that holds the butterfly moves when you push on the governor arm. So with that said, next is to get the air breather off and look and see what is wrong. Screws out of butterfly or something broken. Probably end up pulling the carb off for repairs. If I remove the air breather and fuel tank can I get it off the engine? This is an outside project, no shop so just so much time during the day to work on it. Thanks.

Forgot to say that I did start the pony yesterday. Charged the battery to make sure it was full charge the spun the engine over for 10-15 seconds(ignition off) to circulate/splash some oil around before starting. Did it help? Considering the pony hadn't been started in 3 months I would say it did some. The knock was there but of a shorter time. The motor was choked down and didn't run as fast so that's why.

When I bought my HT4 the pony had a bad knock. I found the pony flywheel was loose. The nut was tight but the key way was wallowed so it could rock. A flywheel from a parts pony fixed it.