Hi all, I recently change the oil pan on the 340 in my 70 challenger. The original had a stripped drain hole and had been overtightened enough it leaked from all the gaskets. I used a new replacement Milodon stock replacement pan.

When I first fired it back up today it dropped back into its usual idle like always but I heard a loud knocking from the motor. At first I was afraid I had blown it up and the rods were knocking, but that didn't make much sense while it idled perfectly, everything else was normal, and all I changed was the pan. Oil pressure was strong as well. I only ran it briefly, not even long enough to warm up.

At this point I'm planning to pull the pan back off and give it a once over. That's a fun job since I have to pull one of my headers to get to it!

Does anyone have any experience with similar issues? Any known issue with the Milodon stock pan on a 340? I'm assuming if something is hitting something its going to be obvious, but anything in particular I should be looking at?

Thanks for any and all input,

-Jon

I think what your hearing is a rod hitting one of the baffles, the windage tray, the oil pickup tube or the edge of the new oil pan
What ever is causing the noise will leave witness marks
Let us know what you find, maybe that will help someone else on here in the future

when you find the offending spot, please take a couple of pics if possible, and post them.
as cab said, this may help for future reference.

Will do, I hope to get to it next weekend.

you need to buy a mechanic stethoscope.
https://www.ebay.com/itm/Mechanics-Sonarscope-Stethoscope-Engine-Noise-Sound/401743522931?epid=3016199960&hash=item5d89c7ac73:g:7vcAAOSwoutcpn9o
will make finding engine noises a breeze, simply move the scope around until the noise is at its loudest and you have zeroed in on the problem. If it is a rod hitting the pan or windage tray, you should be able to feel that noise with your hand on the side of the pan as well as hearing it.

I had a similar thing happen to me. I pulled the pan and inadvertently bent one of the front corners of the windage tray in the process. Started it up and had that tinny knocking sound. Pulled the pan again and the interference was not obvious. Had to turn the engine over by hand before I found the problem, front counterweight hitting the windage tray. Bent the corner back and problem solved

I hope mine will be that simple!

here ya go : https://www.ebay.com/itm/Mechanics-Sonarscope-Stethoscope-Engine-Noise-Sound/401743522931?

I have seen the dust cover on the auto trans get twisted and hit on the torque converter bolts , make a knocking noise .