If your Jeep Liberty CRD needs replacement glow plugs, you might be confused by the different options, including choosing 5 volt or 7 volt editions. This guide will walk you through making the right choice.
About the Factory Plugs
The factory plugs on the Jeep CRD were a new-generation ceramic glow plug made by Bosch. Ceramic plugs are able to get hotter than traditional steel plugs, making cold starts quicker and less smokey. Unfortunately, the first generation of Bosch 7V ceramic plugs were prone breaking off and falling into the engine.
Shortly after Jeep ended CRD sales in 2006 a “light recall” was announced to address the ceramic plug issue. We call this a light recall because customers were not specifically mailed and notified to bring their Jeep in for service, however, if the Jeep was at a dealership the tech could be prompted to perform the repair. This means that this recall was performed on some, but not all CRDs.
The repair consisted of removing the 7V ceramic plugs and replacing them with a 5V steel plug, then replacing the glow plug control unit and reprogramming the ECU (engine computer) for new 5v programming.
Since the new 5v plugs were made of steel they could not get as hot as the ceramic plugs, and unfortunately cold-starting performance suffered. As the temperature dropped owners found they needed to use the block heater more often to get their Jeeps started.
Determining Your Version
Officially speaking, you should replace your glow plugs with the same version that the car is programmed for. The easiest way to determine your glow plug version is to take out a glow plug. The voltage rating will be stamped into the glow plug shoulder.
If your car is chip-tuned (or you are going to get it tuned) your tuner can also tell you which programming you have.
[UPDATE] Running 5V at 7V Programming
As we mentioned above, the 5V steel plugs have not been as effective as the ceramics were at sub-freezing temperatures. Traditionally it was thought that running the 5V plugs at the higher 7V programming would cause the 5v plugs to burn out.
A few members on the LostJeeps CRD forum (if you haven’t joined yet, do so!) decided to purposefully run the 5v plugs on their 7v programmed CRDs to see what would happen – how quickly would they burn out, and would it improve starting?
First impressions were dramatically improved starting, and, now that over a year has gone by, none of the test plugs have burned out yet. It is still a gamble, but, it seems that over-driving the 5-volt plugs has worked for these members.
What did you do?
We’ve taken a few polls and opened a few threads on this topic in the forums, but, we’d love to hear from you here, too.