I think my engine is dying... Rattle Tapping noise.
 

Help,

I have here a S430 that is rattling quite loudly. The rattle or tapping noise is coming from the bottom rear of the engine. When you pop the hood and stand at the cooling fan, you barely hear it. Rattles the most when at 1350 rpm. It doesn't matter if it's hot or cold. What could this be? Car has 146k miles.

BTW, real sorry for the vertical video...

https://www.youtube.com/watch?v=KeB4...ature=youtu.be

Could be engine, could be transmission front pump noise. No real good way of testing the difference without having the car on a lift running and checking for the location.

It does have good oil in it and the correct amount, right?

Transmission front pump? I had a shifter module go bad a couple month back. Caused me to drive the car in 2nd gear and neutral for quite a bit of miles. The 2nd gear clutch plates must have some wear on them, but would that cause the problem?

I've taken good care of the engine. 5-6k mile oil changes with Formula M. (Mobil Dealer Oil, basically 5w-40) Yes the level is correct. It is right up to the MAX line. Which isn't ideal, but it's not overfilled.

EDIT: Also, I haven't lost power either. The pull feels the same as a year ago.

Need it on a lift and use a mechanics stethoscope to pinpoint noise

take it down to any good local garage they will be able to pinpoint it

"Caused me to drive the car in 2nd gear and neutral for quite a bit of miles."

It's called "limp home mode" for a reason. Not meant to be used until you get around to pulling into an AAMCO.

No more delays, get a mechanic to listen. Sounds pretty awful to me.

Or just drive around and wait for a rod to come poking out the side of the block.

Mine sounded like that when the drivers side catalytic converter went bad and started rattling.

Sam

Got it, thanks. I'll take it to my mechanic and get it diagnosed this weekend. I'll report back.

It could just be a loose heat shield, exhaust bolts, or cat-converted. Its hard to narrow it down with minimal details.

My 08 S550 did that exact same noise was the exhaust hanger.. doubt very much that's the engine but I agree you need to get these things checked out right away. It's stupid to drive with issues like this or in limp mode.. especially with a car like this..

So, it was my driver side catalytic converter rattling. But just today, the rattle stopped. Not sure what happened...

It will probably start again.. most likely needs to be replaced.

Parts of the catalyst honeycomb have likely broken up and are sent out the exhaust pipe

or.....it's broken up and sent into the next converter in line if it's the front converter that's giving you the issue.

Through time, if left unchecked (not repaired) the catalyst honeycomb will eventually restrict the air flow through the exhaust and when completely plugged, it will create too much back-pressure and then cause misfires on that bank of cylinders along with the error codes to go along with it.