Troubleshooting exhaust cooling.

[infy]

I've noticed that one of the risers is running much warmer than the rest. What's the next step?

1990 Avanti with twin 302 v8 serial 0C761486.

There are 4 risers total. 3 are cool to the touch and the 4th isnt scolding hot but you don't want to keep your hand on it. It's the port engine starboard side.

I ran it idle throttled to 1k rpm for at least 20 min.

Now that I know there's an exhaust issue how do I determine if it's the riser, exhaust manifold, or something else?

Edit.. engine Temps are fine. Wasn't smoking anywhere.

Edit 2.. and how hot is hot? When is a riser too hot? This is the same riser where I just replaced the rubber pipe between it and the elbow. But that thing could have taken years to fail.

 

[camalot]

If you had a sensor to trigger an alarm it would go off at 212*f .......quite warm to the touch. With out a infra heat gun it's going to be super hard for anyone to give you a real answer. If they hold 90 to 130 * f then nothing to worry about.

 

[alldodge]

Don't think you have an issue. Water flows to the path of least resistance, and most things are slightly different then another, even being the same part. If you can touch it evn for a couple seconds without being burned, its not to hot. Have fun and go baoting

 

[wahlejim]

Edit 2.. and how hot is hot? When is a riser too hot? This is the same riser where I just replaced the rubber pipe between it and the elbow. But that thing could have taken years to fail.

when you replace a section, this is common. less corrosion and debris. Shutters are working correctly. No temperature readings will ever be the same on any exhaust system. Agree with AllDodge, nothing is really wrong right now. Get an infrared reading if you are really concerned about it and let us know what you find.