help exhaust glowing

Catalytic convertor or muffler's hogged up, exhaust can't get out...

Holy night fighters looking for glowing exhaust stacks to find the bombers! This is not normal unless an engine has been running very hard for a long time. I am guessing that you may have roached a turbocharger (if so equipped) or are running so horribly overrich that a lot of fuel is actually burning within the exhaust manifold. I'd actually consider having this one towed to a reputable mechanic.

Best of luck,

--Joe

sihen wrote:

Keep driving it like that, and you'll torch the exhast valves and head gasket, if you don't catch something on fire first...

Tow truck time, if you're smart...

I have a problem with this...and I'm not trying to start a fight or imply that you don't know what you are talking about...because you obviously do...BUT..

A rich mixture cools combustion. It CAN make the area near the exhaust port run somewhat hotter than normal due to continued burning after the exhaust stroke IF...there is a supply of oxygen available to the hot mixture inside the exhaust system.

This is usually not the case, however. It would happen sometimes on the old early emissions control equipped motors that had active or passive air injection into the manifolds...the idea being that any unburned mixture would spontaneously reignite after being expelled from the cylinder, saving the cat from having to deal with it if possible.

In the instance of an extemely rich condition, you would sometimes see them with manifolds glowing hot, feeding afterburn with injected fresh air... But in gereral (no more A.I.R. systems), if you want to see a manifold turn red, an extremely LEAN mix is the way to go about it...a lean mix ignites earlier, burns way hotter and is still hot leaving the cylinder, and at the manifold you'll see temps as much as 300F hotter than normal...hot enough to completely blue chrome on motorcycle pipes, where an over rich mix will just tint them slightly gold, if it discolors them at all...

I could demonstrate this to you if you lived near me, if you point a infrared remote pyrometer at the turn where the pipe leaves the cylinder on a bike, you'll see 500-600F on a well tuned bike, maybe

650-700F on one that runs rich, and as high as 900F on a lean running motor...

Another thing...the cat. It gets hotter the more unburned fuel it has to digest. At a certain point, it becomes too much, and it will begin to overheat, glow, and the interior structures will begin to fall apart, sometimes ending in a complete blockage with burn-through like I believe this person is seeing...so if it turns out that is the case, it would be wise to consider the car's state of tune and correct any problem that might have led to this point...

Unburned fuel in the exhaust will cause the exhaust to glow even without AIR. Retarded timing or crossed plug wires will leave unburned fuel in the exhaust. jeffcoslacker and his pyrometer are also accurate as far as combustion temp and fuel ratio. What you have is a fire inside the exhaust. AIR will make the exhaust even hotter becuase of fresh O2 supplied to the unburned fuel in the exhaust. After all, that is exactly what AIR is designed to accomplish.

jeffcoslacker wrote in news: snipped-for-privacy@no-mx.nodomain.com:

I once saw this exact thing on an '80s Lada Riva (Russian 4WD). It later turned out the carb float had sunk and tons of fuel was being dumped into the engine to the point that the engine eventually stalled and would not restart.

By the time I got to see it, the cat was glowing literally orange and the rubber hanger rings were on fire. Good thing there was snow beside the road. By throwing snow at the cat, we were able to extinguish the fires before the vehicle itself went up.

That was a night to remember, let me tell you.

what are you using for fuel? are you adding any octane? That does that.

Whaaa?:screwy:

When did Lada ever fit cats ?

snipped-for-privacy@codesmiths.com wrote in news:1157715455.446907.8530 @d34g2000cwd.googlegroups.com:

In Canada in the '80s.

Hi everyone just an update Had the car checked at work luckly i work for bus company so thers lots of mechinics about. Pretty much every one was right the cat died. Gotta do lots of overtime to get it fixed. Thought about just putting a staight pipe on there but i far to concerned about the environment to do that so looks like i gotta get the p[ushbike out the shed. Thanks for all the reply's Si... Bristol England

Just gut the cat, it's toast anyway...

Ulf

Most vehicles still have at least passive air aspiration systems. You can't make a catalyst work without some added air in the exhaust stream. Much LESS air is added now than in the days of big air pumps on carbureted engines, but its still added.

Or run with a severe misfire. A misfire causes perfectly-mixed ready-to-burn air/fuel to be dumped into the exhaust plumbing. A dead cylinder or two will melt down an exhaust system pretty easily, which is why for 30 years now its been against recommended service procedure to pull a spark plug wire, even briefly, for diagnostic purposes.

Not without that oxygen you claim isn't available in an over-rich mixture. A catalyst FACILITATES combustion, but it can't create combustion without both fuel and oxygen to combine.

Actually it's to keep raw HC out of the Cat, for the reason I explained before.

There is no combustion occuring in the cat. If there is, it destroys it, as I said. Check your understanding of a cat's job. You have some wrong assumption going.

Also explain where this air is admitted to the exhaust stream. Haven't seen an air pipe on a cat since the mid 90's...an OBD II system with up- and downstream O2 sensors couldn't provide any useful info in an open system with air being admitted post-combustion...

OXYGEN STORAGE In order to oxidize CO and HC, the catalytic converter also has the capability of storing the oxygen from the exhaust gas steam, usually when the air fuel ratio goes lean. When insufficient oxygen is available from the exhaust stream the stored oxygen is released and consumed. This happens either when oxygen derived from NOx reduction is unavailable or certain maneuvers such as hard acceleration enrich the mixture beyond the ability of the converter to compensate.

jeffcoslacker wrote in news: snipped-for-privacy@no-mx.nodomain.com:

If you would bother to check almost every eng still has a air pump. and air passages are intragel with the head, not external. air is still added post combustion as has been since the adoption of cats.

>

Really? As a state liscenced emissions tech since 1991, that's the first I've heard of it, outside of the active and passive systems I've already described, which are obsolete now.

Where is this pump located? I'll have to go check it out.

Wanna explain how a closed loop feedback system with multiple o2 sensors can create an accurate reading of o2 levels in combustion gases if external air is admitted before sensing? I'm fascinated.

Please quote some sources, because I've been looking since you posted this, and can't find a thing about it...

Well, one of the things that's limited us to handwaving in this diagnosis is that the original poster didn't really specify anything about make, model, year, engine...

Leaks can also admit external air where and when the designers didn't mean to, under some conditions.

Anyway, he and friends have evidently established internal clogment of the cat as the problem. So... what caused that? Did it just get old and/or rusty and collapse internally, or was this a meltdown from excess fuel? I think that car needs more diagnosis before it gets a clean bill of health... and in particular, throwing a new cat into a car that tends to plug the things by puking oil and/or macroscopic amounts of unburned gas into them could be an expensive waste of parts.

Cheers,

--Joe