ddc

I have an odd noise that comes and goes. Initially I thought it was the serpentine belt and/or idlers. I figured at 74k miles the OEM belt was shot. So new belt and tensioner idler. The rest are newer and all are quiet. Before I put the belt on I started it for bit, noise still there! It not a squeal, but more of purring sound, and it seems to be coming from the intake area. When driving, it ""doesn't change with rpms"", in fact its as if it keeps starting over and over as the rpms are steady. Removed all the vacuum tubes and hoses with exception of the brake booster tube. All are ok. Its hard to say if it affects my mileage as the Minnesota temps are bordering brutal right now! But I always get 13-14 in the colder temps and 16-17 any other time. No check engine light. Runs as always. I ran starting fluid around the intake to head gaskets, even used propane as a leak tester, no leaks! My buddy who repairs cars suggested the PCV, but there is none. The what would be a PCV vacuum hose attach point on the left valve cover is clean and clear as far as I can tell, and air is going in the motor on the right valve cover. So I think all is well as far as the PCV setup. Any ideas?? That brake booster hose is so hard to get at, I'm suspecting it yet, but can't get at it with this lousy design!!!

papa tiger

I would continue to track the vacuum leak. U will eventually find it. The ones art the very back of the intake manifold comes to mind.

corey_lax

Air filter gasket? There's a foam gasket where you reattach the air filter housing to the housing. Might want to look at it.

Jeff50

Absolutely, this is the problem


I had this sound very loudly at different speeds/rpm's. It is now fixed. Try this. Where your stock air filter is, the black plastic device that holds your filter has a worn out gasket on it on the bottom part of it. It may even be gone. Even if it is there, scrape it off and put weatherstripping in its place. Make sure to have a new filter also. My whistling noise was so loud it sounded like a tea kettle. Now, it is completely gone. My mechanic couldn't figure it out so he replaced the serpentine belt and idler pulley which did nothing to alleviate the problem. I read about this solution and even saw pictures of what I did with the weatherstripping on this forum under the subject about a bogging noise. It is not the alternator or the belt. It is the air intake leaking just below the air filter on the device the air filter installs in to. A 3 dollar fix from lowes. (Weatherstripping).

papa tiger

I remember that thread.

Mechanik

It's a sticky. Bog Down Moan.

ddc

Thanks for the tips, I can honestly say I didn't even look at that air filter seal until 2 days ago, it looked fine. I did replace it a couple years ago with new weather stripping. The stuff could be hard and not sealing. Even before I read that sticky, my thought was, what a lousy design! I could tell air was definitely getting past the foam seal, just by the way the foam was wearing from air intrusion. Another "Better idea by Ford"!