Disturbing, crank/knock sound when turning car off

[RickwithaTbird]

This is my car's first winter. It has been in hawaii all its life, and is now in ohio. Now I have a trans fluid leak, and after hearing some funky noises I checked and found I was VERY low in Power Steering fluid as well. Im thinking the cold weather is f*****g things up. Now when I turn the car off it cranks/knocks once or twice, and it sounds pretty bad.. disturbing to say the least. I hear the same noise while driving too though. When I hit the gas (it doesnt have to be heavy acceleration) after coasting it kinda makes the same knocking/cranking noise and its obvious that its moving parts. If I keep on the gas at the same rate the noise will go away, but after coasting, I know its gonna do it again when I hit the gas. It sucks ***. Any ideas on what it could be? Could something have shrunken due to the cold weather that could cause this? Any ways to fix? ...you know... all the useful kind of stuff... anyways... thanks... Rick

[jgw2205]

crawl underneath the car and grab hold of the driveshaft with the car in park and off. if you can rotate the drive shaft by hand at all then you probably need new u-joints on it. Not a difficult job to replace them on your own, just time consuming.

[97Bird]

Check your codes. It sounds like you have a detonation problem with the spark knock and engine run on after shuting it off. Try running a couple of tankfuls of higher octane fuel.

[RickwithaTbird]

Hey guys thanks fro the replies... Im leaning towards the U Joints. I used to hear it any time I was accelerating heavily, but then it kinda just went away. Anyways, the mental image I got from hearing it kinda goes along with the u joints idea, so I'll check that out asap. Plus I guess Ill run some higher octane gas for a while. Could a half tank do it? I know that you arent supposed to run higher octane gas a lot, but will a couple times be okay? will it affect it at all? also, would that be the kind of thing a fuel treatment might help? thanks again... Rick

[flewthecoupe]

If the car diesels when you shut it off, you have an issue with timing, poor fuel, excess carbon on the cylinders or valves, etc. If it were u-joints you would hear a (one) clunk when putting the car in gear, or when accelerating from a coast, or when letting off the gas pedal after accelerating. Won't happen if your sitting still and shut the car off. The transmission needs to be in a drive or reverse gear for that to happen. Might look into the anti-knock sensor as well as better gas. You aren't going to hurt the car using a higher octane. You will hurt your wallet.

[JR Tigerstar]

Originally Posted by RickwithaTbird

Hey guys thanks fro the replies... Im leaning towards the U Joints. I used to hear it any time I was accelerating heavily, but then it kinda just went away. Anyways, the mental image I got from hearing it kinda goes along with the u joints idea, so I'll check that out asap. Plus I guess Ill run some higher octane gas for a while. Could a half tank do it? I know that you arent supposed to run higher octane gas a lot, but will a couple times be okay? will it affect it at all? also, would that be the kind of thing a fuel treatment might help? thanks again... Rick

How many miles are on your '96?
You might want to run some Sea Foam through the engine to remove any carbon build-up.

[T-bird214]

I started hearing the same type of sound in my '96 T-bird soon before it just died while I was going down the road. When it died it was more like it just lost all power, it didn't just shut off. Before it died I had a mechanic listen to the noise and he told me that it sounded like the flywheel, or a knocking rod. After it died and was in the shop about to get a new flywheel, he found that it was the wonderful 3 cat exhaust that has caused the car to knock and eventully die. The bricks inside the 2 pre-cats had started to fall apart and had clogged up the center cat. $900 later I was wishing that it had been the flywheel instead.