Engine knock

[rdsar2k]

Went to my first convoy activity with my M170. ARMVPA Travelers in AR. It was a 100 mile route with a lot of stops and one of the most organized civilian outings I've ever seen. About 20 miles in I started hearing a knock in my engine that got louder the farther we went. Oil pressure was good temperature was good power was good though the knock got louder the higher the rpm and under acceleration. I made the route but rushed home and took off the covers hoping for a loose lifter. Nope. I fear the worse and suspect conn rod bearing seized/spun. So much for being done.

[rdsar2k]

Okay so I used a long screwdriver as a stethoscope and tried to identify this knock. The fuel pump is the noisiest at idle but it is not the same kind of knock more of a tappet kind of noise. The front of the engine by #1 cylinder plug has the pronounced noise resembling the knock but I do not have enough load on the engine to really bring it out. Oil pressure is 30 cold and 10 to 15 hot. Checked the valves twice and they are dead on. Oil has no signs of metal on the dip stick. Clean and bright. I would disconnect the spark plug wire as suggested here on other posts bit the noise is only under load so it would be difficult to tell while driving. Suggestions? Do I need to take the engine our and inspect at this point?

[Ben Dover]

End play in the Camshaft will make a rapping noise, check to see if the bolt is too long, it is supposed to be a 7/16"-NC X 1- 1/8" with an external tooth washer. Sometimes a longer bolt is used to install the Fibre Gear and the original is not replaced. You can remove the fuel pumb and try to check the endplay by prying the cam back and forth. Did you use the proper spacer for your fuel pump?

[rdsar2k]

Yes I bought a new spacer and fuel pump from Midwest mil as it originally had the wrong pump on it. I checked the thrust of the crank and cam when I was assembling it and all was in spec. Engine spun very freely after torquing all the mains and conn rods. It has the fiber gear and it did turn freely after it was installed. I read some post where a guy added a lubricant to his gas as his guides were sticking. I was considering this but the noise is load enough under load that I don't think I will be confident unless I pulland inspect.

[rdsar2k]

Update:

When I rebuilt this engine I did the static timing as I couldn't see the marks when the light was shined on it. I bought one of those timing pointers and this weekend installed it. When I shined the light on it, it was way off. Re-timed it and it is the miracle fix. Noise gone. Drove it all over to be sure. Funny thing is prior to this the engine would drip from the front and rear main seals after a drive and those drips are now gone also. What a relief! Feel like driving it to work now.