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help exhaust glowing
HI everyone my misses just got back from the shop and says the car is
running sluggish. Also loss of power and when i looked underneith because i thought i could here the exhaust blowing god damn the exhaust at the front end of the car is glowing red hot is this normal i think not but can anyone tell us what it could be. gratefully yours simon |
#2
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help exhaust glowing
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: > HI everyone my misses just got back from the shop and says the car is > running > sluggish. Also loss of power and when i looked underneith because i > thought i could here > the exhaust blowing god damn the exhaust at the front end of the car is > glowing red hot is this normal i think not but can anyone tell us what > it could be. > > gratefully yours > simon |
#3
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help exhaust glowing
Ad absurdum per aspera Wrote: > 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. > > 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... -- jeffcoslacker ------------------------------------------------------------------------ jeffcoslacker's Profile: http://www.automotiveforums.com/vbul...?userid=219638 View this thread: http://www.automotiveforums.com/vbul...d.php?t=616668 http://www.automotiveforums.com |
#4
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help exhaust glowing
jeffcoslacker > wrote in
: > > 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, 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. -- TeGGeR® |
#5
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help exhaust glowing
TeGGeR® wrote:
> I once saw this exact thing on an '80s Lada Riva (Russian 4WD). > By the time I got to see it, the cat was glowing literally orange When did Lada ever fit cats ? |
#6
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help exhaust glowing
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#7
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help exhaust glowing
TeGGeR® Wrote: > > > 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. > > > -- > TeGGeR® The Russian cars of the 80s had cats? -- silicon212 ------------------------------------------------------------------------ silicon212's Profile: http://www.automotiveforums.com/vbul...?userid=388544 View this thread: http://www.automotiveforums.com/vbul...d.php?t=616668 http://www.automotiveforums.com |
#8
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help exhaust glowing
silicon212 > wrote in
: > > The Russian cars of the 80s had cats? > > In Canada they did after a certain point. -- TeGGeR® |
#9
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help exhaust glowing
jeffcoslacker wrote:
> Ad absurdum per aspera Wrote: > >>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. >> >> > > > 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... 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. > if you want to see a > manifold turn red, an extremely LEAN mix is the way to go about it... 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. > > 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 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. |
#10
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help exhaust glowing
Steve Wrote: > , which is > why for 30 years now its been against recommended service procedure to > pull a spark plug wire, even briefly, for diagnostic purposes. Actually it's to keep raw HC out of the Cat, for the reason I explained before. > > 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. 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... -- jeffcoslacker ------------------------------------------------------------------------ jeffcoslacker's Profile: http://www.automotiveforums.com/vbul...?userid=219638 View this thread: http://www.automotiveforums.com/vbul...d.php?t=616668 http://www.automotiveforums.com |
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