Exhaust manifold still glowing.

If you can only see the glow at night then I honestly would not worry about. Could just be a lower quality material used to make the manifold.

 

It takes huge amounts of energy to vaporize fuel (or water for that matter) the energy loss reduces the heat ever wonder why air cooled motorcycles don't cook idling sitting still? You guessed it rich mix. The O2 level is high enough in the manifold that it will not promote combustion even more so with a rich mix. If you did a smog test compare the CO levels and the CO2 levels higher CO2 is a more efficient running engine. What the OP has is most likely a non-issue related to a cheap manifold other wise the other side would be glowing also.

 

^^This^^

Even tho i'd be willing to bet it's just a crap manifold...

 

Would it be worthwhile to conduct an exhaust backpressure test?

http://www.aa1car.com/library/exhaust_backpressure.htm

 

Actually no it doesn't require that much energy. The auto-ignition temperature of gasoline is only 477-536ºF. Average exhaust manifold temperatures are between 752-1112ºF. So raw, unburned fuel that is exhausted into the manifold can very easily ignite, increasing the temperature of the manifold.

 

Water being a liquid takes 7 times as much energy to bring it from 212* to steam than it does to go from 33* to 212* It takes a lot of energy to vaporize a liquid. Granted gasoline will vaporize at a lower temp but it still requires energy to do that. The by product of burnt gasoline contains O2 and CO2 both of them are pretty inert so there is not a lot of left over oxygen to promote combustion no matter how hot the mix is. This is one of the reasons they used to inject air into the exhaust to promote the burning of left over fuel greatly reducing HC emissions.

 

Update: I drove my truck to Austin last Thursday. When I got there, I immediately checked my manifold. It was NOT glowing. Thanks for posting the average manifold temps. I believe I was chasing a problem I didn't even have, as some of you have said. Thanks for all the inputs. Time to do a tune up on my truck now!

 

I would still keep an eye on that since it is a new manifold. Hopefully your hold down hardware and the new manifold can handle the heat. It needs to be torqued and stay torqued correctly. Easy enough to check.

 

As far as I know, all factory cast iron exhaust manifolds glow. You just don't normally see it because of the sheet metal heat shield.

If you are still concerned, check the exhaust gas recirculating tube (EGR) for clogging if you have it. My Gen 1 (1996) Taco had it.


Greg

 

I had the same issue. It melted my o2 sensor, the shop said its engine wire harness issue. I just throw thousands away.. whats the fix boss. Still need help

 

You just revived a decade old thread. Have you tried everything mentioned in it?

 

What are your fuel trims under the conditions that makes the manifold glow?

 

No, after genuine engine harness and genuine exhaust manifold replaced i kinda give up. If a fix thats less a thousand, i will do it.

 

I have a hard time believing anyone can get a cast manifold to glow. The amount of heat needed to make a cast part glow is insane. So your issue is the 02 sensors keep melting?

 

I remember glowing manifolds as being a timing issue. What did the shop do for thousands?

 

any wires around manifold melted, oil filters one side melted too

 

I'd pull the cat and see if it's clogged.