My 98 Dodge Dakota has started to have some significant rattling. When I got under the truck to inspect, it seems that the exhaust system is rattling. The mounts and clamps are all fine but when I knock on both the muffler and the catalytic converter they rattle like something has broken loose internally.
Other than being very irritating is there any problem with ignoring this. Not getting an sensor signals and don't seem to be getting any back pressure power loss.
You betcha.. eventually the "cat" is going to plug up and blow your head gasket, egr and probably burn up some other things.. I would fix it if I was going to keep the car.
If you are not in a I/M area I would probably punch or gut the cat. The muffler is not going to plug so badly it will damage anything but the cat theoretically might.
If you can get away with doing it getting rid of the cat and changing out the muff would be optimal.
Fairly typical failure mode for both mufflers (baffles come unwelded) and catcons (biscuits degrade, shift and rattle). It's entirely possible that only one component or the other has failed internally -- the suspension of the exhaust system is such that knocking the muffler causes the catcon to vibrate as well, and vice versa.
The idiot who suggested gutting or removing the catalyst is, well, an idiot. It won't help your car run better or more economically compared to a properly-functioning catalyst, it will cause your "Check Engine" light to stay on constantly, it *is* Federally illegal, and it will turn your SUV into a gross polluter.
If a clogged cat can "blow the head gasket" on a 98 Dakota (which would have either a 5.9 or 5.2) I'll EAT the blown gasket. All the engines available in the Dak that year were iron head/iron block designs with pretty much indestructable head gaskets (short of running the enigne with no coolant whatsoever).
But yes, a rattling ctalyst can eventually shatter the matrix in the catalyst and restrict the exhaust, which will KILL both power and economy. But it won't blow a gasket on a 5.9 or 5.2!
If you don't have a post-catalyst sensor the engine will never even know. If you do you will need to make firmware changes or come up with a gizmo that provides the "expected" input to the ecu. Probably doable with a couple of dollars worth of parts-either resistors or a tiny DC supply.
Decatalyzing cars is environmentally beneficial if you are not in a major metropolitan area like LA. HC and CO will break down to CO2 whether in the converter or the air. NOx will be slightly more trouble but it too is primarily a smog zone area.
Plus cars SMELL so much better with no catcon....if it didn't have an O2 sensor I'd say throw a tank of 100LL in occasionally just for the good smell.
But, his Dak being a '98, he *does* have both upstream and downstream O2 sensors.
Horseshit.
Sure do,downstream is right behind the catcon
Hey I'm not planning to decatalyze this vehicle. I've been busy running back and forth to the MS coast helping relatives clean up and cope. I don't have time to fool with this thing right now and I just need to know if delaying will cause any permenant damage. Seems to me that I would get an O2 signal if the catylytic converter wasn't working effectively and some back pressure power loss or roughness prior to any other major damage from plugging. Right now it is running smooth as glass and the rattle, while very irritating, is only significant at idle.
Frank
No, if it's running properly you're fine. Excessive restriction would manifest in reduced performance and mileage and easy tendency towards spark knock. Get it fixed when you have the time.
How will the computer know there is no converter?
So everyone who does that call the Feds for your lethal injection right away. Find someone who cares and demand that they follow the law. Do you want fries with that?
Not as gross as a 75 Pontiac. Yawn...
By looking at the upstream and downstream O2 sensors, duh.
Because OBD-II (or is it -III, I always forget?) REQUIRES the computer system to monitor both upstream and downstream (of the convertor) O2 content to detect a malfunctioning catalyst. That's why these cars don't need treadmill-type emissions tests in most areas- they're their own rolling emissions test station. A 98 Dakota falls into that category of vehicle.
But only an idiot would make any car, be it a 75 Pontiac or a 98 Dakota, a GROSSER polluter than it has to be (aside from the fact that it won't pass inspection with a constantly burning 'service engine' light.)
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