I have just had my V6 engine in my 88 GT replaced by a re-manufactured engine. At idle everything is OK, but at 5000 RPM (unter no load -- transmission in neurtal) the manifold starts to glow red-hot.

Exhaust back-preasure, ignition timing, MAP sensor, and fuel mixture appers to be OK.

Any idears what may be causing this? Will every V6 engine do this (never checked before).

First of all, how long are you running it at that RPM before it starts glowing? I know that when my dad helped a neighbor replace the engine in his truck he had to rev it at about 3K for the "initial break-in" and the headers started to glow bright red. That happened after about 10 minutes. I'd think it was normal if your revving it long since the exhaust gasses tend to be quite warm.

take it for a test spin at night if after a mile or two of moderate driving and it stats glowing red you might have a problem how old is the cat do it glow past the manafold

The headers on my Buick Turbo V6 will glow red if I run it in neutral at high RPM. It done it while I was breaking in the new cam. Normal driving it's o.k.

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86 SE Fiero converted to GT (Buick Turbo V6 transplant in progress)

78 Malibu 3.8L Turbo Buick
TURBO WONDER
Best 8th: 1.548, 6.62@106.32 3450lb
TE-70 3 bolt, Ported Stock Iron Heads and Intake
2.5 stock intercoolers
Vernon Swindell, Jr.

quote Originally posted by 862M4inCA: First of all, how long are you running it at that RPM before it starts glowing? I know that when my dad helped a neighbor replace the engine in his truck he had to rev it at about 3K for the "initial break-in" and the headers started to glow bright red. That happened after about 10 minutes. I'd think it was normal if your revving it long since the exhaust gasses tend to be quite warm.

Ebhan: The red starts to be visible after 4-5 minutes (at 3000 RPM not 5000 as originally stated).

Sounds pretty normal to me. Now if it was doing it while just driving around I would be scared and lookin into some kind of exhaust blockage. but honestly I don't think that a glowing manifold after revving in neutral that long is something to worry about.

Check the EGR tube. A big manifold leak will cause this exact condition. Same thing happened to me. Replaced the tube and problem solved. I would not say that a glowing manifold is something to ignore.

I noticed mine does the same thing. If I rev it while in park, or net. the manifolds glow. But after driving the car for more then an hour, racing from stoplight to stoplight the manifolds where fine, not extremly hot either. I think most cars will do this if you rev in netural for that long.