Knocking from engine.

[takimanpgt]

I recently bought a '93 XLT with 131k miles on it. I hear a knocking from the engine while in park @ 2500-3000 RPMs. It goes away at idle and at higher RPMs. I have searched and read up on lifter tap, rocker noises, etc and being new to the OHV concept, am finding it hard to pinpoint the noise. To a layman, such as me , it sounds like rod knock. On the otherhand, the noise goes away as RPMs go up and so I am confused. Some suggestions to what it could be?

p.s : I will clean the MAS sensor in the next couple of days alongwith another oil change to a heavier engine oil ( using 10w-30 right now ). I'll probably also try torquing the manifold bolts and giving the plugs and wires a thorough going over.

 

[Jason_25]

Is there noise when the engine is loaded or only when it is revved out of gear?

 

[takimanpgt]

The noise happens only when the engine is revved while in park/neutral. Once I start driving, I can't seem to hear anything.

 

[boominXplorer]

I wouldn't use anything heavier than 10w-30. Try using a little higher octane gass. I had a little knocking problem like that but i noticed once i got better gas it went away. Start with the basics like cleaning the MAF and the IAC, then sprey out the Throttle body to make sure everything is clean. If that all doesn't work I would try new plugs and wires. Is there any CEL?

 

[takimanpgt]

The CEL came on while on the interstate and went away by itself a couple of minutes later.

 

[takimanpgt]

I did a little more looking around tonight and the sound is definitely from the bottom of the engine. I just can't pinpoint to where I can definitely say the bearings are shot.

Question: How hard is it to open the pan up and replace all the bearings from under the truck?

 

[bikerboy4lif]

the rod or crank will probably need machined too

 

[LukeDog3D]

the engine will have to be removed or at least jacked up a bit to get the oil pan off.