Controlling Jeep Wrangler’s Under Hood Operating Temps
The Jeep 4.0L inline-six was the last true Jeep/AMC engine design before Chrysler bought everything and folded it into the Pentastar family. It was the final derivative of the old 4.2 inline-six and debuted in the 1987 model year. Its last year would be 2006 when the TJ Wrangler ended production.
What Does This Have to Do With Jeep Wrangler Operating Temperatures?
The 4.0L is a massive hunk of cast iron American greatness. But all that cast iron means it’s a giant heat source under the hood, and once it gets hot it holds that heat for a while. Not to mention everything around the underhood soaks up all that heat which can negatively affect performance, reliability, and component life. But with some Jeep Wrangler heat shields, the amount of heat being radiated under the hood can be kept in check, keeping more sensitive components protected to make sure performance doesn’t suffer.
A friend recently picked up a very low mileage (only 18k on the clock!) 2006 Jeep Wrangler Unlimited with the sturdy 4.0L for motivation. One of the first things we noticed when checking it out was how hot the hood was after the Jeep had been running. The hood prop rod was scorching hot when we opened the hood. Didn’t take more to tell us it was time for some Jeep Wrangler heat shields to go into action.
Part one of our blog will cover the different Jeep Wrangler operating temperature readings we took with our trusty laser temp gun. In part two, we’ll show the difference after we’ve installed some different automotive heat shields. To get started, we drove the Jeep to get it up to operating temp before taking some readings.
In our first reading, the air intake tube was reading 135 degrees F. It was the same across the length of the air intake tube. The fuel injector rail read 183.5 degrees F. That’s pretty hot, and means that there is a lot of heat that is being inevitably transferred to the fuel flowing through the rail, even while the engine is running.
Yes, the upper radiator hose is going to be hot, we know that’s just a part of the operating temperature for Jeep Wranglers. We took this reading to verify the accuracy of the Jeep’s temp gauge and to go with our next picture.
This is the high-pressure line for the Jeep’s A/C system. It rests right on top of the upper radiator hose. Besides needing to do something about the direct contact so neither hose or line was damaged, the heat transfer between the two could hamper the A/C system’s efficiency. We’re going to address that with some Jeep Wrangler heat shields, like thermal barrier sleeving, and take measurements to see the difference it makes.
The airbox was reading 180.5 degrees F. So we know we definitely need to install something on the box to shield it from underhood heat. As the cooler air flows through the box, that heat will get transferred to the air, raising the intake air temperature which could hurt performance, especially on an already hot day like we were experiencing.
Now that we have our temperatures, we’re going to regroup, figure out which products we want to install and where then take some after readings and see what we’ve got. Check back with us in Part 2 to see where we went with heat shields for this Jeep Wrangler.
