Hey guys
Got the six running in my truck but of course, there's a problem. Very loud knock. Can't really hear anything other than it when the engine is running. I would assume it is a rod bearing? Any other suggestions?
I'm going to pull the pan tomorrow and check. If it is a rod bearing, how do I go about measuring the rod to see what size bearing I need? I see on rockauto that I can buy undersize bearings...I assume that is to account for wear?

Thanks guys.

Undersize bearings are for a reground crankshaft, not for wear. If your crank is worn the only cure is pulling the motor to repair it properly.

The bearing has a number on the back of it. No number? Standard size. Buy some plastigauge and check your bearing clearance. put the plastigauge on the crank and torque the rod to cap.

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70 Plymouth Valiant 4dr

Thanks guys.
I found out that the knock was being amplified through the exhaust--it was hitting the engine. But it is definitely still there.
Is it possible for the crank to hit the pickup tube if it isn't positioned properly?

Yep, it certainly is. Don't ask me how I know that. And it certainly does make quite the racquet.

If thats the case you can tell fairly easily. Get a bolt in the crank snout and turn it with a breaker bar. Do it with the plugs out, would be easier. You'll feel it hang up for part of the revolution where the counterweight hits the pickup, then becomes suddenly easier. It will be very repeatable, mark the balancer as a reference point when it happens.

Did you have the pan and pickup off for some reason? This doesn't just happen on its own... pickups are a challenge to get off let alone loosen up on their own.

I did have the pan and pickup tube off, yeah. Had to do the rear main and pan seals. Really hoping now that that's what it is. I have another pickup so I'm not too concerned if the one in there has taken a beating. I will check today. Never even thought to check like that for some reason, lol.
Thanks

Boy, u sure are having a time of it with this truck..... I have been following your trials and tribulations on dodgetalk. It is coming along though.... Good luck with it

Kevin

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crossthreads are better than locktite

Oh man let me tell ya...nothing has gone right. The truck is really paying me back for crashing it lol. Thanks for following along...should be back on the road soon.

Turns out it was just the oil pickup tube. Easy fix.

I learned that lesson the hard way too - give the crank a few spins before you button up the oil pan.