94 Grand Caravan 3.0L FI

Nasty clattering rattle on startup, like "metal gargling." Goes away after about two minutes. Sounds and feels like coming from intake plenum, but I think the flat top of the plenum is just acting as a sounding board. With a dowel in my teeth I can feel the clattering equally anywhere on the engine. After it goes away, if I rev the engine, the sound comes back briefly as the RPM returns to idle. The engine starts, runs, and drives just fine. Only a hint of smoke at hot idle, normal for 204,000 miles. No water leak. No engine code.

Possible clues: the noise increases or starts up again when loading the power steering, as when turning the steering wheel to the limit either way. So I removed the accessory belts (serpentine and A/C) and ran the engine, but the noise was still there on start-up and rev-down. So its not the steering pump, or the belt idler or tensioner.

When the car is put in gear, the RPM drops, but the noise does not increase. So the noise increases when the accessory end of the crankshaft is loaded, but not when the torque converter end is loaded.

I suppose one day soon I will look in the rear view mirror and see a piston rod in the road that wasn't there before.

P.S. I can get engine code 55 by flipping the key.
(Oh, that's normal... "end of codes." http://www.allpar.com/fix/80s-codes.html)

 

My 97 3.0 does the same. Has done it since about 150K, now at 215K and no pistons in the rearview mirror. Every mechanic I've talked to says they're just a noisy engine when they get old.

 

Thanks, I really feel better about that, I trust you from your posts.

I remember driving up to some friends in a 90 Voyager and they were looking at the front end and someone said, "It's like a sound effects machine!"

 

i have a cracked flywheel that makes a noise during start up, hmm lemme find the a video that might have it to demonstrate...

crap i don't have a good clear vid of it

-greg

 

The noise is probably piston slap.The piston skirts are worn and no longer fill the cylinder bores as well as they did when they were new.The engine can run a long time like this and there is no real danger.