Dodge Durango Forum II Archive

all the poop.. with care, an easy task..

TomK [MA][99 BW 5.9L FT4WD]
tek@acm.org

the 180F thermostat (as opposed to the OEM ~195F stat) gives you a slightly cooler engine environment. I went to the 180F stat because I had a persistent spark-knock problem, which is lessened by the cooler engine temperature (it turns out that this knock was just my engine whining for an MPP PCM, but that's another story..)

The cooler thermostat in general moves the PCM program to a nicer part of the curve(s), so it can give you a little more oomph (in terms of timing and mixture). Exactly how much the stock PCM does with the cooler temperature I don't know.

The thermostat sits in a housing under the "upper radiator hose", which is right next to the AC compressor on the top of the engine (on a 3.9/5.2/5.9; all you 4.7 owners can stop reading now). There are some subtle things about getting the housing out without pulling the compressor (or losing the bolts), and getting the mating surfaces absolutely clean, that aren't "trivial", but are well within the world of a careful shadetree mechanic.. PepBoys sells both the thermostat and the gasket, though it may take a little convincing to make them understand that.. I prefer to use gasket sealer on my thermostat gaskets, YMMV...

...tom

Wed Jul 31