hey there, i bought a 300 i6 about 4 months ago and the original motor blew a headgasket. I then replaced the engine back to another 4.9 i6 and after about a week of driving it, it developed a knock. all of the sudden i was going down the road and the knock started, it sounds like its coming from the front of the engine, not too sure if its top or bottom end. i have been told maybe a lifter or bearings. my oil pressure is normal and it keeps normal temperature. what do you guys think?? thanks!

 

Use a mechanic's stethoscope or long screw driver and listen for the sounds. Put the tip of the screwdriver against the block and listen through the handle. Be VERY careful that you do not get against moving objects!!!

Sometimes, something may be wrong with the P/S pump, alternator or water pump which will make knocking sounds. Temporarily remove the belts and start the engine and see if the sound is still there. Do not run the engine for long or it will overheat.

 

I have had knocking noises on these trucks from all over the years. As the previous post states, some mechanism. Do not forget to check the pulley on the cam. That one knocks good when loose. If internal, you can always try some slick 50 to assist. Fixing the problem is always the best choice.

 

Mechanical fuel pump?