03 Cobra - BAD Noise From Engine - Seeking Thoughts on Origin

[Sick03Vert]

Hey guys. I hate to post up a thread like this, but I really could use some insight from the community on this one.

Yesterday I went to the tire shop and got my Nitto 555's installed rockon. It's about a 5 minute drive from my house.

I left the tire shop and proceeded to drive the car, easily I might add, down a 55mph stretch of road. No issues whatsoever.

Then I turned onto a 40mph road. As I shifted from 2-3rd, I felt something....kinda just felt like a misfire or something....only for 1/2 a second. Then I hear the most God-awful noise coming from the motor. It sounded like a lifter had taken a shit, or maybe even a rod. It was LOUD..not a "Can you listen and tell me if you hear it", but more of a "I just totally broke my shit" sound.

Following instinct, I shut it down immediately and coasted to the side of the road. Whatever the noise was, it was RPM-dependent as you could hear it slow down as the engine turned off. I got out, looked under the car...no leaks. Nothing hanging. I had no warning lights on the dash, no smoke from the exhaust or under the hood..nothing. Oil pressure and temp were normal. So I popped the hood, checked to make sure nothing had come loose there. All was good. At this point, I was less than 1/4 mile from my house. With nobody home to help, I grimaced and fired up the beast. It sounded like total SHIT. As I gave it the gas, the noise got noticeably louder. I didn't push it at all...just enough gas to get it going, then into neutral and let it coast to the curb.

I should add at this point that the Cobra is my only car...so I can't afford to let it sit while I think things over. That said, there's a Ford dealer less than 4 miles from my house so I thought I would hobble it over there. I really, REALLY didn't want to because I had no clue what the issue was. I fired it up...same sound going on, and proceeded to roll SLOWLY (Under 10mph) through the neighborhood. As I turned out onto a 40mph road, I noticed the noise was going away. I gave it a little more gas...it got quieter. Then, all of a sudden, it went totally away. Everything was normal.

I rolled into the dealership, sat in the parking lot, had the A/C on, and the car was 100% fine. So I took it down the feeder at 45mph...no noise. 75mph on the freeway, back to 45mph feeder, back to the dealer parking lot....nothing. So I took it home and, once stationary and in the drive way, I gave it three good revs to see what would happen. Everything was fine.

I've turned it off, turned it on...nothing. Drove it to work today..nothing.

So my question is: Have any of you guys had something similar happen, and if not, have you heard of anything like this? Any possible ideas as to what it could be?

I want to make sure I give you guys the most information possible, so here's a short list of things that hopefully might help shed some light on this deal:

1. Car was not up to fully operational temp
2. Temp outside was around 60 degrees and weather was clear
3. Car is running Valvoline full synthetic oil. It's a little past due by date, but over 1k under the mileage
4. I did not step into boost at all during the drive (Yes, I'm being 100% honest guys and did not try out the tires)
5. Car is running Chevron 93 Octane and has only run it or Shell 93 Octane since I've had it (about a year). It was not running a fresh tank of gas at the time. It had under 1/2 tank of week-old gas that it had been running without issue
6. Car has no prior mechanical issues since I've had it and always runs like a top
7. Car travels, on average, 10 miles a day...maybe less. More on weekends
8. Current mileage is 21k
9. I am the second owner...mods in sig. None recently installed.

Thank you guys in advance :beer:

****CLIFFS: 03 Cobra, mods in sig, 21k miles, had a bad engine noise (i.e. lifter or rod) which resolved itself during 5 mile trip to dealership. No clue what it was. Looking for suggestions. Thanks in advance. :beer:

 

[coposrv]

If it was a rod or main bearing there is no way it would "fix itself".

 

[Sick03Vert]

If it was a rod or main bearing there is no way it would "fix itself".

I know. That was my original thought before the sound went away. Now I have no clue.

Thanks for the reply though. :beer:

 

[coposrv]

Drain/ change oil and cut open the filter and screen the oil. Pull the valve covers and take a look.

 

[Sick03Vert]

Drain/ change oil and cut open the filter and screen the oil. Pull the valve covers and take a look.

That may be how I wind up spending Sunday...have to work on Saturday. :nonono:

 

[Torch10th]

Have you checked your belts thoroughly? On my 03 I shredded a SC pulley belt down to two ribs. It sounded like I instantly blew the engine. It's possibly that you lost a couple ribs on a belt and what you were hearing were the shreds beating against the hood of the car. If the ribs removed themselves, the noise would have obviously gone away.

That's obviously going to be your best case scenario here.

What you're describing sounds pretty much like a rod bearing taking a crap. The sound going away is troubling in that the bearing is likely completely gone at this point. That unfortunately means you're going to have to do an entire engine rebuild to clean out the mess it makes when a bearing gives up the ghost.

You should also take a look at pulley bearings etc. That's a possibility, but usually those squeal and whine if the bearing goes out.

 

[Sick03Vert]

Have you checked your belts thoroughly? On my 03 I shredded a SC pulley belt down to two ribs. It sounded like I instantly blew the engine. It's possibly that you lost a couple ribs on a belt and what you were hearing were the shreds beating against the hood of the car. If the ribs removed themselves, the noise would have obviously gone away.

That's obviously going to be your best case scenario here.

What you're describing sounds pretty much like a rod bearing taking a crap. The sound going away is troubling in that the bearing is likely completely gone at this point. That unfortunately means you're going to have to do an entire engine rebuild to clean out the mess it makes when a bearing gives up the ghost.

You should also take a look at pulley bearings etc. That's a possibility, but usually those squeal and whine if the bearing goes out.

I checked the belts while roadside and they looked okay...but I will be double checking them at lunch today.

While I appreciate your informed reply very much, I have to say I HOPE that it wasn't a bearing, as my car will be sitting indefinitely if I have to do a rebuild. If that were the case, would the car be down on power? Just asking because I don't know, not in any way being a smartass.

Thanks again.

 

[Torch10th]

I checked the belts while roadside and they looked okay...but I will be double checking them at lunch today.

While I appreciate your informed reply very much, I have to say I HOPE that it wasn't a bearing, as my car will be sitting indefinitely if I have to do a rebuild. If that were the case, would the car be down on power? Just asking because I don't know, not in any way being a smartass.

Thanks again.

Initially, probably not. However with out the bearing in place (or if it's severely worn) you start using the rod end itself as a bearing. This starts to elongate the rod end and leads to breakage of the rod itself because forces on it are not as intended. You get lateral movements, awkward angles at the wrist pins etc.

Reality though is that if one bearing goes, that material is in your pan and there's only so much your oil filter and any magnetic drain plugs can do. That means you've got metal shavings in the other bearings, in the oil pump and riding along the cylinder walls between the piston. If it's a rod bearing that's gone south, the longer you wait to address the problem, the more damage it will cause. You could potentially go from just needing a quick clean-up and replacement bearings to possibly throwing a rod and windowing the block. The cost difference between those two scenarios is quite large.

Definitely check your belts (specifically the blower belt) and make sure it's 100% in tact. That's just a $40.00 replacement belt and your fine. If it turns out your belts are fine, stop driving or starting the engine at all. As suggested, immediately perform an oil change on the car and cut open the filter.

If your filter is looking like this, you've got a bad rod bearing.

If that's the case you'll want to talk with your local machine shops. If you caught it early enough you may be okay with cleaning the crank case and replacing the rod bearings and the oil pump. If the bearing is completely gone and you've got a rod end being used as a bearing, you're going to have to at least replace a rod.

The one thing I'd really do as well is to check out the tune on that car. The 4.6 motors while not invincible, aren't really notorious for being hard on bearings. One of the quickest ways to beat up and destroy a rod bearing is detonation. There could be damage to pistons, combustion chambers, valves etc. that has gone undiagnosed.

You're the second owner of the car, did you do the modifications and tune, or was it done by the previous owner?

 

[Sick03Vert]

The tune was done by the previous owner. HOWEVER, I did have it dyno-checked to verify things were on the up and up.

Honestly, the car almost never sees boost. I just roll it around town and enjoy it.

I had one of the technicians here at the dealer tell me he has seen cases where, in cars with low mileage that aren't driven much, a piece of carbon gets loose and winds up jammed between the piston and the wall. Eventually, the piston just pounds it into dust which winds up blown out the exhaust.

Does this sound feasible? Not to take anything away from someone who has been working on cars for 45 years, but his advice of, "Have faith, get a bottle of Techron for the next few fill ups, and keep driving it" didn't fill me with much comfort. I will be changing the oil either at lunch today or this afternoon. If it has to wait until this afternoon, I'll probably borrow a dealer car to drive for lunch. It's about the only perk of working here.

Thanks again for all of your insight.

 

[Coiled03]

I've had something similar happen, although the noise didn't last as long as what you describe. I dropped a piece of a zip tie down the lower intake manifold when I had the upper off my old Fox body. When I started it up, the thing made a god awful racket for a couple seconds, then went away for good. I never thought anything more of it.....for about 6 months. Then the car slowly started spewing blue smoke, and running rouger and rougher. Turns out I bent a valve just enough that it took that long to wear out the valve guide and start burning oil. Cost me a head removal and a full set of valve guides.

Having said all that, I can't imagine how anything would've entered the intake of your car if you were just driving along, so I wouldn't consider this a very likely scenario for you; just a remotely possible explanation.

 

[oldmodman]

Could the tire guy have left a rag in (or on) the engine and it got caught up by the belt until it got chewed up and spit out?

I have found all kinds of "leftovers" floating around after "mechanics" had worked on a car.

The best thing I ever found under a hood was an entire PowerProbe kit including the carrying case with all accessories. But over the years I have found screwdrivers, wrenches, lots of wire ties, a tire pressure gauge and so on.

 

[oldmodman]

Could the tire guy have left a rag in (or on) the engine and it got caught up by the belt until it got chewed up and spit out?

I have found all kinds of "leftovers" floating around after "mechanics" had worked on a car.

The best thing I ever found under a hood was an entire PowerProbe kit including the carrying case with all accessories. But over the years I have found screwdrivers, wrenches, lots of wire ties, a tire pressure gauge and so on.

 

[Sick03Vert]

I've had something similar happen, although the noise didn't last as long as what you describe. I dropped a piece of a zip tie down the lower intake manifold when I had the upper off my old Fox body. When I started it up, the thing made a god awful racket for a couple seconds, then went away for good. I never thought anything more of it.....for about 6 months. Then the car slowly started spewing blue smoke, and running rouger and rougher. Turns out I bent a valve just enough that it took that long to wear out the valve guide and start burning oil. Cost me a head removal and a full set of valve guides.

Having said all that, I can't imagine how anything would've entered the intake of your car if you were just driving along, so I wouldn't consider this a very likely scenario for you; just a remotely possible explanation.

Dang...that sucks to hear man. I will keep this in mind, though no under-the-hood work was performed on the car. You never know.

Thank you for your post. :beer:

Could the tire guy have left a rag in (or on) the engine and it got caught up by the belt until it got chewed up and spit out?

I have found all kinds of "leftovers" floating around after "mechanics" had worked on a car.

The best thing I ever found under a hood was an entire PowerProbe kit including the carrying case with all accessories. But over the years I have found screwdrivers, wrenches, lots of wire ties, a tire pressure gauge and so on.

My Dad has told me plenty of horror stories of leaving a screwdriver, etc. under the hood and screwing up the hood itself when it slammed shut on it.

For this reason, I am a bit paranoid about my car. Call it a bad trait, but I was never more than three feet from the car while they did the tires, and they never opened the hood on it.

I was trying to think about whether or not they would have left anything anywhere else underneath, like a rag, that might have slung free. Now that.....I'm not sure. Can't rule it out.

Thank you very much for your post as well. :beer:


*UPDATE: I took a long lunch and changed the oil today...no shavings! :dancenana::dancenana:

I took a while to make sure, but even with a fine tooth comb I found nothing in the oil OR the filter. And the oil level was also normal...nothing had burned off.

So the mystery remains, and I realize I may never know. I just have that bad feeling every time I go near the throttle that I'm about to have the shit scared out of me by a rod coming through the damn hood.

After the oil checked out, I thought I'd drive it back to work....and she is still purring along like normal. ZERO fluctuations in any gauges. So I'm stumped.

Thanks for all the replies guys. There are some really bright mechanics on here and it's nice to know you can ask a question, and actually get responses that are worth looking into instead of the "Did it have gas in it?" advice you find on some "other" forums.

Cheers SVTP! :beer:

 

[Torch10th]

That's certainly good news. I would check your plugs. Unlikely, but it's possible you lost an insulator in the combustion chamber. It's about a 20 minute job, so it's probably worth knowing.

 

[Sick03Vert]

Gonna try that now....the noise has returned. :whine::fm:

Guess I'm gonna troubleshoot it this weekend and if I can't get it figured out, I'll get it to Ford and see what they say.

Totally bummed.

 

[ElscottHavoc]

Could it actually be exhaust related? Maybe a loose connection somewhere that somehow sealed itself up...depending upon location exhaust and size exhaust leaks can be obnoxious. Just throwing out ideas really.

I know I had an EGR plug pop out of my headers and made a crazy knocking noise - never went away on its own though.

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[SC Heaven]

Damn man. Never a good story. Keep us posted, hope its not terminal.

 

['88347coupe]

Engine bearing noise wont be intermittent. Engine bearing noise will either be heard on initial startup before said bearing get oil pressure, or it will be constant while the engine is running. It simply will not come and go. The noise you are hearing is valve train related. Most likely gonna be a lash adjuster losing prime. With the miles you describe, the car has sat for long periods of time at some point, and that is not good for these engines.

 

[Sick03Vert]

Could it actually be exhaust related? Maybe a loose connection somewhere that somehow sealed itself up...depending upon location exhaust and size exhaust leaks can be obnoxious. Just throwing out ideas really.

I know I had an EGR plug pop out of my headers and made a crazy knocking noise - never went away on its own though.

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Damn man. Never a good story. Keep us posted, hope its not terminal.

Firstly, to EVERYONE who replied in this thread, THANK YOU. :beer:

I have got the problem nailed down. It is, in fact, exhaust related.

When I was having my tires put on, there was an issue when they lowered the car. The guy lowered the lift and apparently "something" was still under the car. He raised it back up, cleared the object, and then lowered it. I thought no harm no foul. Not to be the case.

Going off of a tip from Elscott in this thread, I took my car to my exhaust shop I always use. I trust their mechanic like family, as I've had an insane amount of work done there and he is damn good. Turns out both of my catalytic converters were smashed. $800 to fix. In addition, fragments had gotten stuck in both of my tailpipes and both my mufflers. They were able to clear the fragments from one tailpipe but the other one needed to be redone AND I needed two new mufflers. To be clear, this was not a bullshit story...I have pictures, which I will try and upload later as I'm currently at work, that show this damage.

So all in all, $1500. Needless to say I am pissed. I have contacted the store manager for the tire store (Discount Tire) and he is doing "research" and is due to call me back.

I know many people, including myself, disagree with those people who try to get money from businesses on damage claims. IMO this time, the shop should pay the costs for repairs. Am I wrong for that?

It probably won't happen, but I think they should. It goes without saying I'll be pressing the issue as hard as I can.

This is DEFINITELY the issue, no question, so the mystery is solved. Thanks SVTP for your contributions, as usual. You guys (and gals) are the best.

I will update this thread with the news of what happens and try to get some pictures uploaded for you all. Just goes to show that the slightest mistake can be expensive. $1500 is a lot of money to me.

Thanks again everyone. Updates as they become available. :beer:

 

[ElscottHavoc]

Glad you got it sorted out, sucks it ended up being such a big cost...$1500 is some serious coin, but the silver lining I suppose is that it was just something external.

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