AA717driver

Running to get food today and the car is driving fine. Windows down, feeling the warm breeze. Went to McD's and ordered at the drive through. Everything sounded normal.

Stop to get gas, fire it up and it's fine. Then, I drive over to Panera and sit at the speaker/menu and I notice this knocking sound. It was coming from my car. The frequency of the knocks increased with the revs.

The tone was similar to the old 60's/70's cars "dieseling" when the shut down.

Is this the "death rattle"?

TC

fpb111

Bad gas? Did you use the green handle?

Leaking oil? Failing IMSB often sounds like marbles cycling around in a can. Oil pressure? Pull the accessory drive belt and see if the noise stops. If so check all pulleys/wheels for play/noise.

AA717driver

Ah. No marbles in a can. Just a definitive knocking sound that rises and falls with revs. I left it in the parking lot at Panera--heard horror stories about driving after hearing a rattling noise.

No oil leak, pressures and level ok so far.

I used BP premium--no diesel. . But it does sound a little like knocking with crappy gas.

TC

Shark Attack

I always used to panic with every car I had at a drive thru. The sounds bouncing off the wall is NOT a good indicator that anything is wrong with your car. Just my $.02

AA717driver

Understand, Shark but this is a pretty definitive knock. I think I'm going to go pick it up and run it to the Indy tomorrow.

TC

Gretch

Remove serpentine belt. start car...... is death rattle is gone, it is the water pump.

I know the sound....... will scare the begeebus out of you. I flat bedded my C4 125 miles to my indy out of fear of doing any irreparable engine damage. Was a good lesson. My water pump was not leaking either, but it was junk. 125k on motor then.

DBJoe996

Could just be a stuck or cold lifter since it follows engine revs. Service history? Recent oil changes? How many miles? Any repairs? Agree with other suggestions to check. Hopefully your shop will figure it out. BTW I would have slept in my car overnight. Had a friend park a BMW locked up tight outside a McD's 24 hour drive thru window and it was busted into within hours. The damage to the inside and dash was astounding. They just busted out the driver's side window....glass all over inside as well. Amazing what some morons will do.

DB's997

Agree! When my water pump went south, it caused a knocking as you describe.
Sounds so bad you do not want to drive it. Flatbed to dealer proved it was the water pump. The car only had 40K miles.

FL-03Carrera

Dropped seat valve?

AA717driver

So, should I drive it the 5-7 miles to the shop or flatbed it?

TC

AA717driver

There are no indications other than the noise. Wouldn't an internal failure cause a dropoff in performance?

TC

P.S.--When I described it to the shop owner, he thought catalytic converter or exhaust issue. But that was an off the cuff assessment.

TSMacNeil

I'd have it towed.
Good luck-

Hurdigurdiman

Flat bed it.

AA717driver

'If you THINK you should, you should...'


TC

AA717driver

Epilogue: I decided to live on the edge and drive to the shop. No sound on startup. No sound whild driving or idling. Got to the shop and the owner pounded on the exhaust and poked around looking for any indication of trouble.

Could have been bad gas or a baffle in the exhaust that came loose then jammed back somewhere. Don't know. Not going to go Krazy trying to fix it.

Thanks to all who contributed their experience to try to solve my issue!

TC