I have a '93 Cadillac Sedan Deville with a 4.9 liter V8 engine and when I'm driving, it tends to rattle when I have my foot on the gas, but it won't rattle when I have it in park or neutral. If anyone knows what causes a motor to rattle and possibly has a solution to it, I would greatly appreciate any assisstance.
-- Thanks in advance.
That sounds like pinging, which could be caused by a number of things, including a timing problem, cheap low octane gas, or an overly heavy foot.
---Bob Gross---
I had the same thought upon reading your post. If it sounds like bb's in a plastic bottle, it's engine detonation. Older V-8 in luxury cars are especially prone to this as the carbon build-up on the pistons reaches a threshold from low RPM only operation. There are professional engine decarbonizers available. The other solution is to run premium fuel, and make sure to floor it more often. GW
Robertwgross wrote: That sounds like pinging, which could be caused by a number of things, including a timing problem, cheap low octane gas, or an overly heavy foot.
---Bob Gross---
Timing, Timing, and too much Timing.
Or a broken centrigfugal advance (spring?) in the distrubritor.
10 years on the car, sounds about time.MIKE.....
Except that the Caddy 4.1/4.5/4.9 never *HAD* springs in the distributor. The computer controls timing on those.
They are notorious for pounding like someone's sledge-hammering the pistons if the EGR valve sticks closed. Thats where I'd start.
EGR. I have mine disconnected because its opening too much. As such the engine is 'pinging' I believe its called when I accelerate. 95 blazer.
Without seeing and feeling it, it's hard to diagnose, but it sounds like you (the OP) could have a warped / bent driveshaft or bad universal joint. Check your driveshaft !!!
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