Please Help Troubleshoot Engine Noise - Car Forums and Automotive Chat

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02-14-2005, 07:10 PM

2/14/05

INTRO

To "introduce" myself, I am the owner of a 2001 Hyundai Elantra with automatic trans and ABS/TCS.

I really like my car. I've had a few things fixed under warranty—including a new dash clock and new front struts—but I've NEVER experienced the notorious Elantra shimmy or any problems with burnt out bulbs, check engine lights or the like (knock on wood). I'm posting today regarding one of THREE “unsolved mysteries,” which my service department has yet to correct: The first mystery involves a thumping/knocking sound that I sometimes hear from the rear brake area while depressing the brake pedal at a stop light and AGAIN after pulling into the driveway, putting the car into PARK, taking my foot off the brake and pulling up the parking brake (I then hear thump, thump, thump, thump, thump for about 20 seconds); Mystery No. 1 is an inconsistent problem that seems worse in cool and damp weather. Mystery No. 2 pertains to the fact that I've had my car pressure tested three times in two years, but no one can figure out why I've had to add 16-24 oz of coolant over the past two years to bring the antifreeze reservoir up to normal. The THIRD MYSTERY, which the rest of this post is devoted to, is the one that MOST troubles and annoys me: I hear a loose, rough engine noise above the normal engine sound, and it seems most apparent when my windows rolled up*. So far, I've searched the Internet forums far and wide and found a couple of possibilities for the source of the Mystery No. 3. I decided to post here in hopes of bouncing some ideas off of y'all before I talk to the service department again and/or possibly Hyundai corporate. From what I’ve seen here—and I could be wrong—there are more people who actually work as mechanics and/or for Hyundai here on this forum. So I really hope you can bear with this long post to help me out!

*WHAT IT SOUNDS LIKE

I hear a loose, frog-in-the-throat type sound whenever the car has been sitting long enough for the engine to completely cool down (overnight to as few as four hours in cooler weather). I don't really notice it while idling in PARK, but I begin to hear the noise when the tac drops and I begin to back out of my driveway. It starts up again when I press the pedal after putting the car in DRIVE. When I come to a Stop Light and remove my foot from the accelerator, I don't hear the noise. As soon as the light turns and my foot is back on the gas pedal, I hear the noise start up again. It sounds like a chunk of rock or pebbles. The tumbling noise seems to keep pace with the RPMs (the sound is progressively faster and louder when accelerating through first, second, third and fourth gear.) If I drive fast enough or hit higher RPMS the engine seemingly drowns out the noise. Strangely enough, in the mid AM hours the sound fades out in five minutes or slightly less. In the PM or very, very early AM (late at night) I hear the sound for as long as 20 minutes. In other words, the sound seems WORSE and lasts longer when I drive at night as opposed to the first startup of the day. I've considered that the roads are MUCH quieter at night, which might account for it seeming louder and lasting longer. The other factor that comes into play at night is that in my area sometimes heavy condensation builds up on the exterior of the car (that, and the car has usually been driven less than 8 hours earlier). This might explain why in dry or warmer weather I am less likely to hear anything and what I DO HEAR fades out quickly and doesn't get quite so loud to begin with.

DEALER EXPLANATION

The first explanation I was given at the dealer—when the car was only three months new—was “lifter noise.” I had family in the auto business growing up and I know a persistent noise of this nature isn't "normal" as the dealer has tried to claim. The sound has grown a bit worse over the past few years to the point where passengers are beginning to comment IF they happen to be along for the ride following the first startup of the day and/or late at night. One passenger described it as a pelting sound like “rain drops” and another person said my engine sounds like an "Autotopia car” (a reference to a Disneyland ride). An independent mechanic recently inspected my Elantra and concluded that it sounds like "valve or engine noise;" however, the mechanic's brother—who co-owns the shop—repeated the dealer's comment that anything serious would have tripped an idiot light or "knock sensor" by now (which hasn't happened).

MY TAKE

Personally, what I hear doesn’t strike me as the rhythmic tapping you get from metal-on-metal lifters. It SOUNDS more like a frog-in-the throat—literally as if something is tumbling loose under the plastic engine cover. It's irritating to the point where I wish the engine would just cough it up and spit it out—whatever it is.

TROUBLESHOOTING

After searching online, I've been offered couple of possible leads:

1. EXHAUST MANIFOLD: Hyundai corporate advised me about a voluntary campaign to inspect and replace cracked exhaust manifolds in select model years, including the 01s. After leaving the car for inspection earlier this month, my dealer claims my manifold is NOT cracked.

2. CAM/SPROCKET NOISE: Two different people on two different Hyundai-only forums mentioned that it could be a cam belt or chain noise contacting the engine housing and/or rattling against two opposing sprockets until such time as the engine heat expands the chain/belt/tensioner and takes up the slack. In both cases, the Elantra owners' mechanics adjusted or replaced the cam tensioner/spring, and the problem was eliminated. My dealer says that they are not aware of any need to inspect, adjust or replace the cam tensioner. Meanwhile, though, I've also noticed a gradual loss in gas mileage—I now average 235 miles per tank vs. 260 MPT—and an occassional rough idle following WARM engine restarts. I don't know if the two observations are connected, but with respect to the 2-3 MPG drop, my dealer recently inspected the engine for proper timing and they have concluded that no timing or idle adjustments are necessary.

3. SHORT BLOCK: Elsewhere it was mentioned that the short block on some Elantras can begin to move 1/8" to 1/4" causing rough engine vibration (not sure if this applys to me or how easy it would be to rule out the problem).

4. SPARK KNOCK: Someone else mentioned spark knock, but my factory-installed sparks are still well below replacement mileage.

5. PISTON SLAP: Someone suggested "piston slap." I have no idea if there is a relatively easy test or inspection to rule out this possibility.

6. HVAC LINES: Another person mentioned HVAC lines causing noise when rubbing or contacting one another. Hmm…

7. ROD BEARING: I read something about a rod bearing going out due to lack of sufficient lubrication and/or a defect. Apparently this defect precipitated total engine failure.

8. LIFTER NOISE: Some believe it is the valves prior to the oil from the pan lubbing them properly. So far, the dealer claims to have measured valve clearances (no problem, apparently). The dealer refuses, however, to oil pressure test the engine. Instead, my service advisor tried to offer the explanation that "all Hyundais do this" (lifter noise). A year or two ago, I started up a new car and heard a somewhat similar noise on that Elantra's engine too, but it went away in less than 30 seconds—and that was in PARK, whereas my noise is evident only after taking the car OUT OF PARK and persists much longer. The first dealer mechanic to hear the noise described it as a "slight tapping" three years ago but offered no explanation. An independent mechanic said it sounded like valve and/or engine noise and advised me to have the dealer take a look at the car. Unfortunately, my dealer won't do anything further because "we would have to keep it here for a month" to cold start it. As a result, they released the car again last week with NO explanation. It's spent over two weeks at the same shop in four years for this very reason!

9. AC SPROCKET/BELT: Someone mentioned that a sprocket in connection with the A/C accessory belt was loose and created a rattle in their car. Elsewhere I found a discussion that referred to a second person who actually had the belt come entirely loose while driving (causing a breakdown).

10. PULLY: It was suggested that perhaps a Power Steering Pully might be coming loose, also causing a rattle noise. As far as I can tell just by driving, I don't note any steering issues (other than the fact that my steering wheel has seemingly pointed a few degrees downward on the right side since purchase—but that's another story).

11. HEAT SHIELD/CAT: The first action my dealer took three years ago was to "tighten" a heat shield but this didn't help at all. I read somewhere else about someone having the problem eliminated after the whole assembly was replaced (along with the CAT). Apparently, if anything breaks loose in there it can make a real racket (but then why would it pipe down 5-15 minutes later?) It's a long shot, but yet another suggestion that was made to me.

QUESTION

Okay automotive sleuths, where should I start? What out of this list would be easy to check and how do I go about choosing what to check first? Alternately, are you aware of any other possible cause that isn't mentioned above? Is there a solution of any kind? And assuming it IS the worst possible cause—bad lifters, short block or rod bearing—how do I go about persuading Hyundai to DO anything about possibly having a lemon for an engine? I have ultra low miles on my car and I have a feeling I might actually run out of warranty before whatever is rattling busts completely loose or some other catastrophic damage occurs. I would prefer a simpler explanation, but if it were that simple why hasn't the dealer fixed it? For that matter, I've offered to pay out of my pocket to sidestep the warranty vs. dealer/corporate hassle and they STILL refuse to look further (ostensibly to save me the money of possibly barking up the wrong tree and inspecting/replacing the wrong part). Does it sound as if they know something I don't?

Sorry for the long post. I really don't want to rant against Hyundai! I simply need help communicating to these folks in terms they will appreciate and take seriously. I decided to write this post up as thoroughly as possible to anticipate your questions and in hopes we can put our heads together to solve the mystery. Thanks for being here!

P.S. If you read this months or even years from now and want to contact me, please reply and an email notification will be sent to me from this forum. I may STILL need your help OR maybe by then I have found a solution to one or more of the "unsolved mysteries" so that I can help YOU (assuming any of this sounds familiar).