(?) noise - awful but went away
 

My wife's 2003 protege5 just did something horrible sounding. Too set the scene...

The car get's driven 30 miles one-way to commute to work, five days a week, plus week-end driving. We've had it since September 2003 and put nearly 36k on it.

We just came off the highway and I drove a mile or two to the gas station on the way home. After filling up, I cranked the engine and began to lift my foot from the clutch pedal. As the clutch engaged, I began to hear and feel (in the pedal and the shifter) a sharp clacking sound. I stepped back on the clutch and reset the shifter into first. I then pulled away from the pump with no problem. As I turned out of the station, onto the road, the noise came back. The noise is related to engine speed (not wheel speed) and sounds like two pieces of metal knocking together. I pulled off into a side steet and stopped the car. The noise didn't stop until the engine did, and did not change - aside from with engine speed (same noise in or out of gear, on or off the clutch pedal). I shifted once or twice in order to get out into traffic and then off the road.

After sitting and thinking for a minute with the engine off, I decided to just try to drive home. I cranked the engine and popped the hood. Nothing looked out of place, and the sound was a loud and clear single clacking that seemed to come from the underside of the engine (flywheel? clutch?). I backed back out into the road and started to drive home. After shifting short (to keep RPM down) through third or fourth gear, the noise stopped around 3k rpm and didn't come back. Driving in fourth, I began to feel slipping. The slipping feeling would last about half a second, but recur frequently. It would slip once every second or so for a few seconds (resulting in a pulsing feel), then it stopped as I let off the gas.

Other than the noise and slipping I think everything else was normal - clutch pickup, pedal travel, pedal feel, etc. Since it's Sunday late-afternoon, I'll have to wait until tomorrow to call a dealer, but boy do I hate the idea of missing work to go to them!

Can I get some advice or help diagnosing this?

HHmmmh. 'Same noise in/out of gear and in/out clutch' says this is probably the engine :(

I wouldn't drive it - have it towed to the dealership (if under warranty).

That's a reasonable thought. However, I did already drive it to the delership.

I drove it this morning about 15 or 20 miles to Jim Ellis Mazda in Chamblee (Atlanta, GA). I haven't gone back to pick it up yet, but I have received two messages from the service department today, explaining that they were unable to reproduce the noise. So they won't be able to do anything to service it.

If it's in the engine, can someone help me speculate about what it could be? Just don't say anything about a zero clearance engine... please :crying:

What if refueling mixed some garbage up into the fuel line and caused some kind of knocking sound?

Sheesh, I've got to go. Please tell me what you think. I'll be back tonight.

Thanks,
Fred

Sounds like a broken finger on the pressure-plate, clutch fork, or throw-out bearing.

Keep documentation on EVERYTHING. Have the technician sign a statement for eveything he says. If you are pursuing a warranty claim - this is essential.

Well, since Sunday evening, it has been driven about 80 miles with no further reports (from the wife, me, or service tech) of noises.

I am normally very nervous about taking it to a dealer (this was its first trip), but I am very pleased with the way things went. I was given a free loaner, two updates during the day about how diagnosis was progressing, reasonable conversation with the service advisor, and good documentation from them regarding the symptoms reported, action taken, etc. Plus, they washed the car (not thoroughly) and vaccumed the uphostery.

I'm still a little nervous about the noise coming back and warranty being a problem, but their handling of the situation (especially since I didn't buy the car from them) has helped me to relax.

So, I'll be letting this sleeping dog lie for a while, hoping that it was related to something in the fuel or some other short term situation.

My initial concern was that it was something like what Rusty suggested. I'll cross my fingers.

Thanks guys...

So, I've edited the title of the first post in this thread, because now feel like a big dum bass... my mouth flapping open and closed...

The problem went away until the weekend, when it came back, at first subtly, then in a new form. The noise appeared once or twice paired with a rough idle. Then the rough idle persisted, and the noise did not return. I thought, "well maybe it's the spark plugs I replaced six thousand miles ago." So when I changed the oil, I pulled the plugs to check them out.

One looked marked on the tip (around the outside) and looked to me like it had been hit by a very small hammer, so that is was dented. It reminded me of hand-wrought iron, because you could see the places it had ben hit be the hammer. At the time, I recognized that the one was different from the others, but I didn't know why. I'm still not sure, but I know that my first guess was wrong. My first thought was that cylinder was not firing at all, and that was the reason for the plug looking funny. Obviously, in retrospect, that could not cause that appearance. So I think to myself, "if the plug is not firing consistently, I should close the gap a little, to be sure it fires." This was, of course, the exapt opposite of correct... thus, I feel like a doofus.

So this morning, my wife drives it to work, after we've had a little trouble cranking it, and eventually gets a check engine light. Tonight I took it to the AutoZone, where they read the code and the guy there helped me realize the problem. I have regapped that plug, by opening it up. The light has gone away, and the ldle has smoothed dramatically. I'm sure this is not news to many of you, by this point.

So now I have two questions.

First if the plug was causing the initial clacking noise, what was that?

Second, do I need to get a new set of plugs and be more careful about their gaps this time?

Thanks - Fred

Well, I'm definately getting new plugs, CEL came back.

Should I just drop it off at the dealer, or can you guys help me?

Well, after a new set of plugs, it still idles a little rough. The CEL was on yesterday, but off today.

I guess it'll go to the dealer on the way home today.

What could be making it idle funny if the malfunction was a misfiring plug that has been replaced? Could gas treatment or a tank of premium help?

Just for the record, the plugs were NGK gapped to .044 as recommended by Advance Auto Parts who sold me the plugs.

You need the codes. Have them read them - they may be different.

Code was for sporadic misfire. Tha's why I replaced the plugs. I was feeling like I must be fairly incompetent, because replacing plugs in not brain surgery. I was using the right plugs, adn being very careful about the gap, but it wasn't fixing the problem.

The dealer has it today, and confirmed the code. They've checked the plugs, wires, coil, (and distributer?) and come to the conclusion that I had some bad fuel. I'll talk to them again in a few minutes, to confirm and see what they recommend.

You guys have any suggestions for dealing with bad fuel? I have already run out the tank that I picked up when the issues first started, and I just refueled Thursday morning. There are probably 40-50 miles on the new tank (Chevron, 87 oct.) right now.

"Must be bad gas" is the default 'We have no clue what is wrong' answer!

That seems to be the case. They haven't done anything to fix the car (only test parts). At least they have been nice and it hasn't cost me anything.

The rough idle has ocasionally disappeared, but is generally present. It results in difficult starting and the CEL is back. I've run about five complete (13 gal) tanks through it, including two bottles of STP gas treatment. I'm out of ideas.

Suggestions?

I figure if i take it back to them, they'll start throwing parts at it. That's not very attractive, but might be better than nothing.

Well, the dealer has tracked it down.

Are you ready?

Stuck EGR valve.