AHHHH HELP!

[Pheonixx77]

ok i dont get this one...i been driving my truck for awhile now lke this and i cant figure this one out. SORRY FOR POSTING IN 911, BUT MY TRUCK WILL BE DOWN IF I CANT FIX THIS. "its a rattling sound" like shaking a dipstick in the tube. i cant pinpont it but i know it is NOT any of the heat shields, they allready fell off. it sounds lke spark knock, maybe bad gas? i put in some 93 octane and the rattling lessened, but still exists intermittently. No noise at idle or reving to 5000rpm's at idle, only while driving. sounds like the tranny, but i doubt it. god dA#@ this is frustrating.

 

[Alec]

Try cleaning the MAS and running fuel injector cleaner. Also if your plugs and wires have more than 50k miles change them.

 

[Pheonixx77]

MAF was recently cleaned, plugs and wires have less than 10k on em.

 

[MrShorty]

If it is spark knock, then cleaning the MAS and the injectors are two quick items that have been known to cause spark knock on the 4.0 OHV. Other common causes are carbon build-up in the cylinders, and vacuum leaks. One "unique" vacuum leak that is quite common on the early OHV was through the lower intake manifold gasket. The bolts come loose over time, and tightening them down is usually enough to fix it.
Good luck.

 

[Pheonixx77]

do i have to take off the upper intake to do that>? or can i get in there with a socket extension and a universal socket? how many bolts etc...???

 

[MrShorty]

I tighten my lower intake manifold bolts with the upper intake in place. Others choose to remove the upper intake. It's up to you which way you want to go. With the upper intake in place, a couple of the bolts can be tricky.
I can never remember if there are 8 or 10 bolts, but they are listed in a Chilton's manual along with the tightening sequence and torque specification.
And don't forget to check for other vacuum leaks (loose intake tube, broken vacuum line, etc).