Dr Iven

Hey guys, I need help with my girlfriend's 2000 V6. I consider myself pretty handy when it comes to things of a mechanical nature, but I can't quite figure this one out, and you guys seem to know your stuff.

Background:
The car has 51,000 miles on it.
She is overdue for an oil change.
No history whatsoever of mechanical failure.
No engine modifications, pure stock.
5-Speed tranny.

OK, I was driving the car this afternoon in the mall near my house. A few cars in my lane were slowing down to turn down a parking aisle, and I switched lanes to avoid slowing down. I got the RPM up to only about 3k, and then I heard a funny noise that sounded like I had 2nd gear in only half-way. I reshifted into 2nd, then upon acceleration it flat out sounded like a diesel engine. "Oh, crap." It was noticeably underpowered as I pulled it into the parking garage. I popped the hood and smelled exhaust. My first thought at the sound was that it had lost a cylinder or thrown a rod, which I knew couldn't really be a possibility. Although the oil was pretty black, it was still fluid and there was plenty of it on the dipstick. There is also a very muffled knock. Not really a ping, but a knock-on-wood sound.

Now, in my opinion, it could be one of a few things. Either the oil filter is clogged, the exhaust is leaking, or something has cracked. We left it up at the mall, and her sister came and picked us up. Do you guys have any guesses as to what it may be?

jgsmuzzy

Could it be an ignition failure? If one of the coul packs has gone faulty, it would lose a lot of power, sound awful, run rich etc etc

Just a thought. I doubt it is a problem with the oil, modern cars can run on virtually no oil whatsoever. I had a Renault for 3 years, put 48000 miles on it and never changed the oil once!

James

mr-mstng

Sounds like a rod to me. Bearing go bye-bye?

If the oil filer was clogged, the oil pressure would be higher than normal. Is that the case?

Dr Iven

Oh wow... I went by the car around midnight last night with a flashlight and my toolbox. The single exhaust pipe on the right side of the engine had been severed just before the O2 sensor and catalytic convertor! I've never seen something like that happen before. There was a little gap where the exhaust was passing through, and boy was it loud! I imagine the knocking was the result of the O2 sensor sending back a faulty reading, which changed the engine's timing.

Lucky that mall security wouldn't let the tow truck pick up the car earlier last night, because my girlfriend actually just drove it like it was to her house. This morning, she took it to her brother's shop and they just welded it together. Good as new! Thanks for the help, guys. I appreciate it.

jgsmuzzy

That's really strange!! Is it an aftermarket exhaust?

Dr Iven

Nope, bone stock!

It just flat-out broke apart... all the way around!

I reached up and grapped the exhaust around the transmission area, and it was freely wobbling. Wasn't even scraping the tube it was supposed to be connected to, which makes me think that maybe a piece fell off.

jgsmuzzy

I'm going to have a look at mine, it is the same year but with more miles!

How far from the Cat was the crack?

Dr Iven

Hmmm... a few inches, I'd say.

You can see the piece I'm talking about if you look down into the engine bay. Find the cat shield and look just above it. It's about halfway between that and the header flange. It was a clean cut, and there is no rust, but it was nasty!

mr-mstng

Wow, that's odd. I wonder if a broken motor mount could have contributed to that.

jgsmuzzy

And if it was a motor mount (which I hope it's not!), get it checked out as soon as, that can cause so much damage in the long term!

Dr Iven

Nah, the motor mounts looks to be in good shape. I'm not sure what did it, but I did notice that the dripoff for the A/C comes out right on that piece that broke. Maybe there was a connecting piece there that rusted so bad it lost its integrity.

conv_stang

geez, glad it wasnt anything serious. could you have hit a speed bump or something? probable just rust, maybe a backfire from the cat lighting off, or something rupured the exhaust?????????

Dr Iven

Nope, no speed bump... just changed lanes and gave it some gas in 2nd gear. I tried my hardest not to panic, as it wasn't my car, but it sounded awful!

jgsmuzzy

As the AC was dripping onto the exhaust, that might have caused some kink of metal fatigue, V. hot exhaust, cold water, the metal would keep getting tempered in one place, that might have caused it??