As some of you have read I just picked up another 98 with a 2.5l. The engine is making a knocking sound thats very similar to a rod knock. I pulled the motor and started tearing it apart today. When I pulled the oil pan I expected to find loose or spun bearings but they are fine. I pulled all the bearing caps and they show very little wear. Same on the rod and mains. So the next thing I can think of is bad lifters...will they make a loud knock? There are a few that are loose but I'm not sure if its just because the oil has drained out. I am not experienced with these 4 cylinders but have rebuilt quite a few v8's. Any advice?
John

 

How about a cracked piston. what's the knock pitch (sound)? I've had a piston crack down on the skirt around the wrist pin and it sounded a lot like a rod bearing. Let me talk to my dad...I think there's a way you can test it where the sound changes under load. Hand brake or brakes on while in gear and revving the engine. I just can't remember how the sound of the knock changed.

 

does it sound like this?

i never figured out what it was, then i hydro-locked it and threw a rod.

 

No when it was idleing it didn't make the noise. when you give it gas it started. You don't have to have it in gear. I suspect the lifters.
John

 

yah, mines taps or clicks right around 2k rpm.

 

I ended up putting it back together, but I haven't driven it. I've only moved it around the driveway. I think the sound that I was hearing was either collapsed lifters or the broken smog tube (where it conects to the ex manifold)I repaired.