Ford Explorer: More insight on the Chirping Explorer

Everyone,

I apologize in advance for the length of the post that follows. This is a
puzzling problem that I have been chasing for almost 2 years and I could use
the collective experience of the group to help me solve it. There are
several others with similar problems, so I hope this will benefit others.

Almost a year ago I began posting messages to the group regarding an
intermitent chirping or squeaking noise that both my 94 and 95 XLTs make.
The noise increases in frequency and volume with the engine RPM. It does it
occassionally in idle, but most often when the RPM are above 2K. It does it
VERY often but it comes and goes during driving and is extremely
unpredictable (except in the fact that it seems to stop...without
fail...ever time I take it to the shop). I had many respond and suggest a
cracked flexplate and many other respond with belt pulleys or belt driven
devices as the possible culprit. After many months of detective work, I am
narrowing the field of options and need some help narrowing it further.
Here is what I know to date:

I have replaced the scerpentine belt, tensioner (which was broken) and idler
pulley (which had a worn bearing). These did not solve the problem. I have
taken the truck by the transmission shop and they have driven it (without
being able to reproduce the noise) and concluded that based on empirical
evidence, the transmission appears to operate within normal limits. I
invested a few bucks in a stethoscope in hopes of narrowing the origin of
the noise. I have been somewhat successful in my efforts. I checked the
alternator and AC pulleys and they are not the culprit. The noise eminates
from the rear of the engine compartment and I can hear it quite clearly when
I touch the steth. to the engine block right at the firewall.

Tonight I had a break in the storm. The noise was very pronounced when I
left the office so I took the truck to the tranny shop. The owner (who has
been helping me try to locate the source) listened to the noise and poked
his head around underneath the car and said "That noise is not coming from
your transmission. It is coming out of your exhaust system." True to form,
I left the tranny shop and drove 25 yards across the parking lot to the
MIDAS shop to let them hear it, and it stopped when I pulled up to the
store.

I talked to one of the mechanics who suggested a few options: 1) cracked
exhaust manifold 2) catalytic converter malfunction [as a side note I have a
check engine light on that throws a catalytic converter inefficiency code]
or 3) leaky exhuast manifold gasket.

My questions are these: 1) Is this type noise consistent with one or more
of the problems I just mentioned? 2) How much am I looking at to fix these
problems?

I had the MIDAS shop check the cat. converter when I started getting the
Cat. Converter Code and they said that they banged around on the CC and did
not hear any rattle that suggested worn or loose parts. They claim the CC
code can be indicative of an O2 sensor that is about to go bad, but in light
of my problems, I wonder if the CC is the source of my problem.

Whew...that is a lot of info. What do you guys think...assuming you did not
fall asleep reading this post?

"Mike Mayer" <netcom.com> wrote in message
news:VaPxb.25161$news.atl.earthlink.net... 
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Timing chain, perhaps??
Dave

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