So I've been battling an on again off again issue with my I35 that sounds to me like a rod knock. I've had it into the dealer like 5 times and they keep coming up empty, so I'm going to consult my usual mechanic, though he has never worked on this car before. BUT, I want y'all to lend your ears and offer some advice/feedback.

Please view the following video:
http://www.mst.edu/~jricca/I35engine.zip

When ice cold, the engine started so rough it sounded like a rod was coming through the hood. This is the first time that has happened in over 3 months. But, the knocking sound you hear in the video is pretty much constant, hot or cold.

NOTE: Car has 87K, is fresh on all fluids and tune up items

 

Where is "The STL". Better off putting a car-part motor in it than dropping the tranny and upper pan and m.t.l. getting the crank machined.

Didn't watch vid, you-tube ftw

 

STL = St. Louis.

Some web research is showing me that others who had this problem traced it to the serpentine belt for the A/C. Does that sound plausible?

What about the knock sensor?

 

If you turn off the A/C, does the noise go away? What do you mean running rough? Does the engine vibrate more than before, or just the noise?

 

A/C seems to make no diff. to my ears. As for the "rough" part...take the knock sound in the video and amp it by 10x...definately sounds metallic is nature...

 

Take it to a shop, on a flat bed. Unless you are ready to tackle it yourself.

 

How's the oil level?

 

Does it do it consistent enough that you could remove the serpentine belt for 10 minutes or so and know if it is gone or not? A problem with an accessory driven off of the serpentine belt is very plausible.

Rod knocks tend to go away once warm initially.

Can you get the video on you-tube?

 

Oil level is good.

Also, I drove the car to work today (20 miles, all highway), and when I got to work, the noise was gone totally.

So, as shown in the video, the noise is there at idle, even when warm. However, it does not get louder with increased engine speed, regardless of temperature. ALSO, after a few minutes of driving, it goes away totally.

I'll try to get it on you tube tonight for y'all.

 

But overall, the problem is not constant - as in it doesn't make this noise every time it starts cold. This is the first time this noise has been back like this in about three months...

/this is driving me nuts, lol