A really bad noise

[arctictraveller]

Since I have begun traveling in weather well below freezing I have started hearing a loud rattling noise under the van first thing in the morning. At first I thought the exhaust system was falling off (again) but once I drive for a few minutes it goes away. It's unrelated to road bumps or potholes, and today I finally noticed that I can duplicate the noise when I'm parked and it's still cold, by modulating the throttle, so no doubt it's either the muffler (new) or more likely, the converter has come apart inside. What I can't figure is why it stops when it warms up (and expands?) anyone ever had this happen? In addition, I had a tune installed (5.4L) by Ramsey's friend Juan, and he said he "eliminated?" The converter. I can't imagine this had anything to do with issue but I also don't understand what he really did. Any ideas?

[carringb]

Check exhaust crossover pipe clearance to the transmission crossmember. It sits close. Bad muffler hanger or even bad motor mount can make it just barely touch and vibrate loudly.

In my case it was the motor mount. Of course, I couldn't pinpoint it until it was so far gone, that when I downshifted to hold my speed, the engine flopped over and busted my right side exhaust manifold.

[rallypanam]

Or a heat shield bouncing around.

[Jsweezy]

Carringb stories never disappoint.

[Dirk Mitchell]

Depending on mileage, 5.4s are known for a couple odd noises.
Low oil -- Even a bit low will make a noise until the oil pressure builds up it can also be a clogged up oil filter causing the same noise.
Exhaust leak, usually on the passenger side the bolts holding the manifold to the motor will rust and crack, after it heats up it seals better and the noise subsides.
Last and hopefully not what you have Timing chain guides, and tensioner. If the guides have cracked or worn out the chain is slack against the inside of the cover and makes a noise until the tensioner tightens it up and the noise goes away.

[BroncoHauler]

Catalytic converters can make all kinds of noises if the material inside is cracked. As far as eliminating the cat with a tune????


Herb

[86Scotty]

Originally Posted by Jsweezy

Carringb stories never disappoint.

I had exhaust shields come to pieces on a 5.4 van once. Really noisy and annoying. Kinda like driving around with a few cans of marbles rattling at certain rpms. I don't remember if temp had anything to do with it.

As for the 5-Star tune 'eleminating' cat thing I bet he just meant he changed some settings in the tune, perhaps turning off 02 sensors or something. If you didn't have a cat, or a hollowed out cat, you'd know it when you were around the van with it running. It will choke you! I bought a Jeep with no cat once. My idea of a Jeep is a convertible and a soft top thrown in the corner of the garage. If the weather's bad, don't take the Jeep. Anyway, it like to killed me driving that open Jeep with no cat. I had it put back on.

[arctictraveller]

Thanks for the ideas. Since I'm back to living in camp, I haven't had time yet to get under the van, but I'm convinced it's in the exhaust system, not the engine. As I mentioned, it sounds like a can of ball bearings rattling around and the noise can be changed based on the amount of throttle applied when cold. I'll report back once I get an oportunity to find the problem................