New CRD owner, preventitive

geordi · **Posted:** Sat Feb 23, 2019 7:41 pm

timothyd wrote:

Got the jeep up and running today and took it for a test drive, has anyone ever had issues with the sun roof making a slight flapping noise at highway speed when the windows are down? Only seems to do it then but not with the sun roof cover closed. It is also only about 40F here and it only reached the first 1/4 mark on the temp gauge, is that normal for factory thermostat?

The sunroof noise is likely a reaction to the air pressure changes from driving with the windows down, and is minimized with the cover closed.

The factory thermostat (or whatever replacement the previous owner may have used) has failed open, the gauge should be at vertical or a needle-width left of vertical when the engine is at proper temperature.

WWDiesel · **Posted:** Sat Feb 23, 2019 10:04 pm

timothyd wrote:

Got the jeep up and running today and took it for a test drive, has anyone ever had issues with the sun roof making a slight flapping noise at highway speed when the windows are down? Only seems to do it then but not with the sun roof cover closed. It is also only about 40F here and it only reached the first 1/4 mark on the temp gauge, is that normal for factory thermostat?

It should at normal operating temperature run a tic to the left of 12:00 (197 degrees F) on the Jeep's temperature gauge as pictured below.
staying at 1/4 is telling you your thermostat has failed to the open position as that is what it does when the internal wax filled bulb fails.

TURBO-DIESEL-FREAK · **Joined:** Sat Apr 17, 2010 3:29 pm **Posts:** 1167

WWDiesel wrote:

timothyd wrote:

Got the jeep up and running today and took it for a test drive, has anyone ever had issues with the sun roof making a slight flapping noise at highway speed when the windows are down? Only seems to do it then but not with the sun roof cover closed. It is also only about 40F here and it only reached the first 1/4 mark on the temp gauge, is that normal for factory thermostat?

It should at normal operating temperature run a tic to the left of 12:00 (197 degrees F) on the Jeep's temperature gauge as pictured below.
staying at 1/4 is telling you your thermostat has failed to the open position as that is what it does when the internal wax filled bulb fails.

WWDiesel:

You are indeed correct that if the O.E. temperature gauge needle is sitting at the 1/4 mark, (after the engine has warmed up as much as it can), the O.E. thermostat assembly has failed.

However, it has been shown time and time again that the O.E. temperature gauge is notoriously inaccurate and non-linear. The needle in the position just a tic to the left of vertical can mean the temperature is anywhere from 170 degrees Fahrenheit to just over 200 degrees Fahrenheit.

This inaccuracy lends credence to my claim that these O.E. gauges were deliberately made this way so that knowledgeable customers would not clue into the fact that the engines were running too cool, even with a fully functional O.E. thermostat assembly.

This is also the reason why you plug in an OBDII reader, or install a digital temperature display if you really want to know how hot your engine is running at.

New CRD owner, preventitive

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