Ok so I am bumfuzzled. Just put a v10 with an automatic in my project truck and it has a knock coming from the bottom end toward the rear of the engine. Sounds like a rod or main bearing but its not acting like one. The knock comes and goes. I can start it cold and some times its there and some times its not. The sound does not get louder with acceleration. I can only hear it at the lowest rpms. I can not figure this one out without taking the engine apart. Does anyone have any suggestions?

 

Whats oil pressure looking like? Just for kicks.

 

Oil pressure is great. I went through the oil system before I put the motor in. I made sure the oil passages were free and clear as well as went through the oil pump making sure everything was right by the book and added a new oil pressure sending unit.

 

I think I would drop the pan and plastigage the bearings, especially since you said it sounds like a bearing. A bad rod bearing may not drop your oil pressure enough to be noticeable especially with these Dodge gauges.

 

Easier said than done. Have to pull the motor up to get the oil pan off. There is not enough room between the front crossmember and the the engine to get the oil pan down enough to clear the crank weights and oil pick up tube. I noticed this morning that when I accelerate the knock gets faster but not louder. Once I put it in gear and got the tranny fluid flowing the knock got quiet. I could still hear it but not as loud.

 

I would crawl under there with some stethoscope or other, and try and verify exactly where the noise is coming from. Might be as simple as a loose converter bolt. (and they sound like a rod knock...)

 

Agreed. Start small first, and work your way up.

Hopefully it is not a rod.

You mentioned the front crossmember, so I am assuming that the truck is 2wd.

If it is, you can indeed drop the oil pan without removing the engine...

Gotta drop the pickup tube into the pan in order for it to come out "smoothly".

It's a tight fit, but can be done.

Edit: not sure if you "project truck" is a Dodge. If not, my oil pan info may not apply.