I've got a 2004 MPV with a cracked cat and possible rod knock here. I got this car as a mechanic special. I knew the cat was cracked as it roars when revved up, but what I believe to be rod knock only appeared after about 10m of driving. Temp is steady, and oil pressure light came on (only at idle) after 5m. I had some difficulty starting when the engine is cooling down. Oil level is at the top of dipstick, so I'm guessing the oil pump could be burnt and/or there is a lot of sludging in the engine oil galleys. Of course the cracked cat could be causing problems, but I'm not sure what they would be.
I'm looking at low cost solutions for this problem. My instinct is to run a solvent through the oil passages and then change the oil. Perhaps when the oil is drained I could pull the oil pan and replace the worn rod bearing. Maybe resurface the crank journal a bit while I'm there. Car is end of life so I don't want to spend too much effort, but the interior is clean and the trans is shifting OK.

Do others have experience with these problems? Is this engine worth saving? Thanks for any advice.

 

I found this the other day. I figure I might do this at some point in time. This might be your issue?