Hi,

First off, I know this post looks long - my apologies! - but as you
can see upon closer inspection I've broken the text into a lot of
bullet points to make it an easy read.

General Question

With respect to the following two mechanical mysteries, am I too far
along to file for Hyundai arbitration? Or might there be solutions?


Car Stats:

2001 Elantra GLS
Automatic
Stock everything
Only OEM parts (including oil filters)
ABS/TCS 4-wheel disc brakes


First Longstanding Problem:

· An acceleration rattle started around 150-300 miles and is growing
worse with time

· This frog-in-the-throat sound takes place under acceleration and
low RPMS (up to about 40mph - then it either goes away or engine
noise drowns it out).

· I hear no abnormal engine noise when completely stopped at a light.

· This acceleration rattle lasts 10-20 minutes in duration, whereas
it used to last less than 5 minutes.

· The noise is worse when engine is cold or car was previously driven
roughly 2-4 hours beforehand.

· The sound seems louder in cool/damp weather [winter fuel blend????]

· It is not so obvious in hot, dry summer weather [summe fuel
blend????]

· Gas brand and octane rating makes no difference [that I can tell]

· I have a 2mpg drop in fuel efficiency (the car only makes about
20-21mpgs in city driving for past two years or so).

· Just this past week: Dealer replaced OEM Spark Plugs with NKGs
(same spec). Original plugs were carbon-fouled though there is less
than 30K on odometer and these are supposed to last 100,000 miles (but
car is 5yrs old so could this still be "normal"?). Dealer blames carbon
deposits on bad gas, not on whatever causes the engine rattle or ping
in the first place.

· I've never seen a CEL entire time I've owned the car. Beginning to
think one or more sensors don't "talk" to the computer since there is a
problem everyone can hear yet it never trips a check engine light.
Dealer seems to be of the general philosophy that if a check engine
light isn't on, there is no problem. On the other hand, everyone who
has heard the problem doesn't deny it (including the corporate rep).

· Dealer efforts to fix or explain problem include: Heat sheild
"tightened". "Cold selenoids are noisy" (tech tells me in 2001). Dealer
finally agrees to measure valve clearance (first one in 2002 normal,
second one in 2004 "out of spec", final one conducted the very next day
by Hyundai corporate rep finds "no problem"). Next told that I am
hearing lifters and this is a normal sound until oil gets from pan to
lifters (true, I hear lifter noise but that lasts about a minute at
startup whereas the other noise seems to be related to acceleration).
Little over a year ago this same Hyundai rep checked my car's thrust
washer/bearing (no sign of metal debris, no problem found (NPF).
Hyundai Customer Service Hotline alerts me to Exhaust Manifold recall:
Dealer checked but finds no sign of cracks so they did NOT replace
exhaust manifold. Motor mount replaced over a year ago - no change or
improvement on noise.

· What I've done: Tried oil additive. Tried higher octane (a few
years back - didn't notice an improvement). Tried gas additive -
injector cleaner?-about two years ago (only resulted in rough idle
and misfiring engine).Been using 10/40 oil instead of 10/30, which is
what the dealer uses at oil changes.


My Impression

Based upon what I've been told about the condition of my spark plugs
- despite only 30K on the odometer - it sounds like a case of
"spark knock". I suspect either a bad knock sensor that the car's
computer doesn't receive valid data from or a sticky valve lifter or
bad valve guide. I've also heard, though, that a rattle or pinging type
sound in the engine can come from the timing belt tensioner. It IS true
that when I lift the hood I hear some tapping from under the plastic
cover. So can anyone vouch for that theory?



Second Longstanding Problem

· I have ABS and four-wheel disc brakes. Almost since Day One I hear
the rear brake/wheel thumping at stops, which oddly enough sounds
almost like someone stuck in the trunk and pounding lower right side of
the car body with a fist!

There are two things that bring on the thumping sound:

· Sitting at a stop with my foot resting too lightly on the pedal -
in which case if I let up or stomp down harder the thumping noises
disappear.

· Second, I sometimes hear the same noise after I first pull into my
driveway, put the car into park and pull up the emergency brake. It
goes on about 30 seconds and anyone standing on the driveway or
sidewalk when it occurs can hear the sound too.

· The dealer has been unable to reproduce the noise and so they have
done little or no diagnostic work.

· Last week I had my car in for an oil change and now the dealer says
my rear brakes are in need of replacement but not the front. A year ago
I had 50 percent remaining on the front and 30 percent remaining on the
back brake pads. Now I have 20 percent left on the rear of the car (but
they didn't tell me the figure on the front.) The dealer wants me to
pay for rear brakes even though they admit that the front brake pads
should wear out somewhat faster than the rears.


My Impression

Normally, I would agree that brakes are wear-and-tear items and I
should foot the bill. But based on a conversation with an independent
mechanic, I feel some or all of this should fall under my warranty.
Reason: The independent mechanic told me that if there is more than 10
percent discrepancy between the wear on the front and rear brake pads
- which is true in my case - than there is a possibility that
something is grabbing or the ABS is kicking in when it should not be
and wearing down the rear brakes prematurely. As stated, I've been
hearing this brake thumping on an intermittent basis for years and it
is on record at my dealer that I've complained of it. So who should
pay? For that matter, what could cause disc brakes to do this? Could
the rotor be warped? What else might cause this noise?



CONCLUSION - I need all the help I can get!!!!!!!!!!

My dealer can't seem to put two and two together. Meanwhile, I've been
visiting Hyundai forums for years to try to get a leg up or a helpful
word of advice (which diagnostics to perform and in what order, for
example). The only Hyundai discussion I've come across that seems to
have REAL Hyundai techs is HERE, so I'm hoping I that if you are one of
them you can reply to this post (thank you!).

Can anyone else reading this post relate? If so, was there a solution
to a similar problem on your car?