Exhaust Manifold Glowing Red ?

[cferry7]

1989 Toyota Pickup DLX 22RE 4wd

After Rebuild Replacement Welding of All Exhaust from First Exhaust Downpipe to Tail Pipe. Removed Catalytic Converter, Cut Original First Downpipe from Exhaust Manifold, Weld Of All components, New Muffler, New Tailpipe, New Oxygen Sensor, New Intermediate Pipe.

Now Exhaust Manifold is glowing Red after significant warmup / run time.

Head Temps at Idle are 280 - 320 deg F.
We are considering that the Exhaust Manifold
( since it is Original Equipment ) has lost its protective coating or something ?
What could be a possible cause ?

 

[KidVermicious]

1989 Toyota Pickup DLX 22RE 4wd

After Rebuild Replacement Welding of All Exhaust from First Exhaust Downpipe to Tail Pipe. Removed Catalytic Converter, Cut Original First Downpipe from Exhaust Manifold, Weld Of All components, New Muffler, New Tailpipe, New Oxygen Sensor, New Intermediate Pipe.

Now Exhaust Manifold is glowing Red after significant warmup / run time.

Head Temps at Idle are 280 - 320 deg F.
We are considering that the Exhaust Manifold
( since it is Original Equipment ) has lost its protective coating or something ?
What could be a possible cause ?

Every time I've seen that it's been caused by unburned fuel lighting off in the manifold. Is the truck running rich?

 

[flyinhawaiian01]

Also check timing and valvetrain, those two will drop fuel into the manifold and make it glow red too.

 

[Bad_Vision]

Running lean will also cause this but your first step should be to verify valve timing for sure!

 

[Ahlem]

Wow, somebody else from Grand Rapids MI.
My son has the 4 Runner up in the UP at school at the moment.