My Pete rebuild

[Nostalgic]

I haven't really seen it discussed much here, but just like the updated oil pumps seem do a pretty good job of maintaining consistent oil pressure across a fairly wide RPM and temp range, the new updated oil cooler housings have really narrowed down the control of oil temps.

I used a new housing kit (with aluminum cooler element) that came with a 235* thermostat pre-installed. It seemed to bring oil temps up to 230 pretty quickly and maintain that temp. A hard pull would see 240+, and even with the fan on coasting down the other side, it was just about impossible to get it to dip under 220.

Switching to a 215* thermostat cruises right around 212-218, and even on a hard pull with coolant at 210, the oil will barely break 230. I think this is due to tighter tolerances and a lot less "leak by" of the thermostat into the cooler element.

Old style on the left vs new "small bore" housing thermostat on the right:



4386527 is the number for the new style 215* thermostat. I'm pretty sure all recon engines now come with the newer housings. EPA class probably dictate which thermostat Cummins installs in them.