When I say HOT I mean it. I've always been aware that my girlfriends TJ exhaust system gets hotter than I'm used to. I didn't think much of it because I've seen other Jeep owners gripe about this with seemingly no root cause. The engine is in good tune (plugs look good, exhaust has no smell). It has no vacuum leaks, I've replaced the intake/exhaust manifold gaskets in the past, no codes, MPG is where it should be.
I note from the carfax that the original cat and exhaust were replaced at a Jeep dealer in 2001 around 38,000 miles. That cat is still there, but the system was replaced again around 2007 with 60,000 miles by my girlfriends father. And then by me in 2011 with 80,000 miles. Currently at 92,000.
Does extreme heat increase the oxidation rate of the metal?
In 2011 I had the exhaust on my Accord and the Jeep replaced at the same time by a shop I like that bends their own. After 4 years the Accord's is nice and grey (despite being my winter beater) and Jeep (which is kind of pampered and sees little to no salt and limited mileage) started to look rough after only a couple years. It sounded bad too, the insulation in the muffler couldn't take the heat. I painted the whole system with Eastwood Rust Encapsulator when I did the frame over in Spring 2014. It all burned off on the first trip, even the end of the tail pipe, it has a max temp of 400 degrees.
Right before the last state inspection the muffler developed a hole on top. I started it up cold to feel around for the location of it. This is when I noticed just how hot the exhaust gets, it was scalding hot in about a minute. After it cooled I put JB Weld on the hole,(max temp 600). The next day I went for a short drive and the JB Weld disintegrated into this charred brittle mass.
I wish I had a heat gun to know exactly what the temps are. The Jeep is a short vehicle so the cat and muffler are close to each other. That plays a role, but the end of the tail pipe shouldn't melt your skin. I think it more complex, perhaps a tuning issue. Jeep may have used some lazy timing figures. I've hooked my scanner up to live stream data and make sure my IAT sensor is reading correct temperatures. (if they read falsely high it will force the computer to retard timing). There is no way to adjust timing on this Jeep. The only trick I know of to advance it would be wire in a resistor on the IAT sensor so it reads the coldest temperature possible at all times.
I ordered this Dynomax replacement system tonight, I'm curious to see how it handles the heat. http://www.amazon.com/gp/product/B000CIXO3U?refRID=PYHFTMV8HJA99PG3TJYC&ref_=pd_ybh_a_1
I note from the carfax that the original cat and exhaust were replaced at a Jeep dealer in 2001 around 38,000 miles. That cat is still there, but the system was replaced again around 2007 with 60,000 miles by my girlfriends father. And then by me in 2011 with 80,000 miles. Currently at 92,000.
Does extreme heat increase the oxidation rate of the metal?
In 2011 I had the exhaust on my Accord and the Jeep replaced at the same time by a shop I like that bends their own. After 4 years the Accord's is nice and grey (despite being my winter beater) and Jeep (which is kind of pampered and sees little to no salt and limited mileage) started to look rough after only a couple years. It sounded bad too, the insulation in the muffler couldn't take the heat. I painted the whole system with Eastwood Rust Encapsulator when I did the frame over in Spring 2014. It all burned off on the first trip, even the end of the tail pipe, it has a max temp of 400 degrees.
Right before the last state inspection the muffler developed a hole on top. I started it up cold to feel around for the location of it. This is when I noticed just how hot the exhaust gets, it was scalding hot in about a minute. After it cooled I put JB Weld on the hole,(max temp 600). The next day I went for a short drive and the JB Weld disintegrated into this charred brittle mass.
I wish I had a heat gun to know exactly what the temps are. The Jeep is a short vehicle so the cat and muffler are close to each other. That plays a role, but the end of the tail pipe shouldn't melt your skin. I think it more complex, perhaps a tuning issue. Jeep may have used some lazy timing figures. I've hooked my scanner up to live stream data and make sure my IAT sensor is reading correct temperatures. (if they read falsely high it will force the computer to retard timing). There is no way to adjust timing on this Jeep. The only trick I know of to advance it would be wire in a resistor on the IAT sensor so it reads the coldest temperature possible at all times.
I ordered this Dynomax replacement system tonight, I'm curious to see how it handles the heat. http://www.amazon.com/gp/product/B000CIXO3U?refRID=PYHFTMV8HJA99PG3TJYC&ref_=pd_ybh_a_1