knock in 45

got a knock in my 45 but i can only really hear it under a load.  sounds like its coming from frount of engine.  havnt had time to tare into it.  any ideas were to start. thamks for any help.

A few years ago I had a "clunk/knock" that sounded like it was in the lower end of the crankshaft.  Ultimately it crapped out.  Found out upon engine removal that the four bolts holding the flywheel to the crank had broken over time. 

There's only a set screw on top of a set screw, if it has power steering from all of the ones I've torn apart. Normally, it will have one large set screw with a jamb nut.  Rick

I'll third the front crank pulley. Also you should check to see the front angle iron under the engine is not loose. There is a specific preload to this iron that holds the front of the engine. I've seen that being loose with only one bolt holding it and it was striking the front pulley. Has to be shimmed correctly otherwise you can crack the clutch housing which I have also seen.

Missed the under load part so ya might be bearings. I had a WD I bought with that kind of knock too.

Here's something to think about. I had a WD45 a while back that had just had the engine rebuilt and ran perfect. I used it to do some light logging with and one day while pulling a log I heard a knocking sound. I used the tractor with this knocking sound for about a year, before other issues came about and I decided to part it out. After taking it apart, I noticed that the clutch input shaft was very badly worn where the pilot bearing rides and the pilot bearing was shot. I was sure this was the problem that caused the knocking sound. I pretty much confirmed that when my brother's D17 needed a clutch. We took the tractor apart and found the clutch input shaft was worn very badly...just like the one on the WD45 I had. This tractor was also used for logging and would really knock loud when under a load...especially when the tractor leaned a lot to the left or right, when pulling logs uphill. We replaced the torque tube (which was easier than disassembling the old one)with one that had a real good input shaft and that solved the knocking sound altogether. Point being...maybe it sounds like it's coming from the engine, but maybe it's NOT actually the engine at all. However, it could be a number of things. Just something I'm throwing out there. Rick

On a WD, or WD-45, if I hear a knocking under load, the first thing I suspect is my left knee...

...but that's just me.   

Wow, that's a new one for me!

If you suspect a knock coming from a con rod bearing or wrist pin you can take turns pulling off one spark plug wire at a time with the engine running to see if it makes a difference.