Too clean exhaust?

[mkinttrim]

My son has a 99 4.0 and his tailpipe has rust inside of it! Don't most exhausts have a light grey caoting? His truck does not have a leaking head gasket or anything, all fluids remain the same at all times. Could it be clogged cats?

 

[NMB2]

its pretty clean if it doesnt have any coating in there. wouldnt worry about it.

 

[srteach]

Any time you compress air (is in an engine cylinder), you squeeze moisture out of the air if there is any humidity at all. The rust is probably normal. Any coating (except ceramic) inside a pipe will oxidize with heat and water. You have both in exhaust.

 

[RotorFX4]

a little rust is normal. it's usually caused by water in your exhaust. water is one of the primary byproducts of gasoline/hydrocarbon combustion. you ever notice how water will drip out of your exhaust before your engine has warmed up completely? it condenses from the exhaust gases onto the cool exhaust pipe and drips out. completely normal.

 

[SixFoFalcon]

To top it off, the moisture that condenses in your exhaust system is acidic, which accelerates corrosion. Does your son do a lot of short trips in the truck? Typically after about 10 minutes, the pipes, mufflers, etc. get hot enough that any accumulated moisture evaporates; any less than that, and you are leaving that moisture in there while the truck sits and waits for the next trip. Back in the days when OEMs used non-stainless steel for exhaust systems, vehicles that saw mostly short around-town trips went through mufflers and pipes in fewer miles than highway cruisers or vehicles used on commutes longer than 10 mins or so.

It's all kind of a moot point though--with your son's exhaust being stainless steel, you really have nothing to worry about as it would take about a million miles for that rust to perforate the metal.

 

[gw33gp]

The light gray film that you use to see on the inside of the exhaust pipe was due to leaded gasoline. The use of unleaded gas will leave anywhere from no deposit to a thin black film. A carbon steel exhaust with no aluminized coating will eventually show rust.

 

[doorgunner]

My son has a 99 4.0 and his tailpipe has rust inside of it! Don't most exhausts have a light grey caoting? His truck does not have a leaking head gasket or anything, all fluids remain the same at all times. Could it be clogged cats?

rust only?
what gas mileage is it getting?
what brand of gasoline?
how many miles a week is it driven?