I have a 1997 f-150 4wd with a 4.6L. It has 110,000 miles and has been very very well maintained. A few months ago, I noticed a rattle in the engine when it was reved above idle. I finally got around to taking it to a friend that works on engines at the ford dealership I used to work at. At first he thought it sounded like a cam chain tensioner, but after using a mechanics stethescope at numerous places around the engine, he said it was coming from the lower intake manifold. He could not hear the noise anywhere else. My questions are; has anyone heard of the lower intake making any noise like this? Do you think if I replace the lower intake manifold it will fix the problem? I don't want to tear it apart and find out that the manifold wasn't the problem. Thanks for all of you feedback!!!!!!!

 

Hi.

I think these engines have IMRC.

https://www.f150online.com/forums/sh...runner+control

If this is loose/broken, could it be a source of noise? Only a teardown will tell for sure. Throwing any codes?

Cheers
Grog

 

Nope, no codes.

 

Well, it's fixed. The valve in the lower intake was stripped and that was making the noise. Dealer wanted $900.00 just for the lower intake!!!! I got an upper intake with throttle body and injectors along with the lower intake for $85.00. It pays to do it yourself!!!!!!