Hi all,

I've been waiting for almost nine years to post these results, but here it finally is:

In Sept '06, we bought our '06 dealer-demo CRD with 26k miles on the odometer. It was kept in stock condition until approx 50k miles, where I went to the elephant hose mod only. It was run in this condition until Aug '14, when the biggest mods were done. At that time, with 115k on the odometer, the CRD had a lifetime, hand-calculated mpg avg of 20.31. I installed the Weeks intake and a Green Diesel eco tune, and the total cost (incl the downloader/code reader) was $935. The mpg avg since these last mods (ie, the last 85k miles) has been a hald-calculated 23.27, for an overall mpg increase of 2.96 mpg. Overall, it's taken 85,490 miles and 3,674.58 gallons to reach the break-even point on my $935 initial investment.

I thought some here might find this info interesting, so let me know your thoughts on it...

Steve

SJBrooks:

Are the modifications you write about the only modifications you have done? If this is all you have done and mileage is your main concern, there is more that you can do.

You would get even better mileage if your engine was running hotter. The O.E. thermostat assembly is a good design, but it is an assembly where the valve inside is sealed up in a cast aluminum housing. The thermostat valve inside of it opens up at a low temperature to help combat NOx emissions in the North American market. The rest of the world gets a 195 degree valve in their O.E. thermostat assemblies; we here in North America get a 176 degree thermostat valve in our assemblies. You can thank the Environmental Protection Agency for this, and Daimler/Chrysler for taking advantage of the regulations and creating a device that limits the life of the engine and gets poor fuel economy.

Plus, there is the problem of the O.E. thermostat prematurely failing, thus requiring replacement of the entire unit. The O.E. thermostat is a good design, but it is poorly executed/manufactured and fails after about 50,000 miles.

Hi TDF,

Up front, I'm going to say that INDEED, fully replacing the OE thermostat with one of the non-OE aftermarket ones is truly the best way to go. However, comma, I'm also going to say that the in-hose thermostat mod (a 195 degree, with a small by-pass hole drilled in the flange) is how I've run my CRD for the last 125,000 miles. Keep in mind, I've towed a 3,000 lb trailer in NM summers/wind/altitude many times with this mod in place, with no overheating or other problems. Perhaps I've just been the one-in-a-million lucky guy about that though...

At my next timing belt change (due soon), I'm going to properly replace the in-hose thermostat.

Steve

a lower stall torque converter will give you a couple more MPG as well. Or you could do like me and run it on WVO mix. I've probably got a few hundred thousand combined miles on it with zero issues as long as you don't try to do it when the ambient temperatures drop below 50 degrees. Or do a full two tank conversion and run 100% WVO.

_________________
GDE FT Ecotune, EHM, Weeks kit stage 1 & 2, Carter 4600 lift pump, Upgraded tranny, Fishing boat hauler!
New at 164K: head gasket, rockers, exhaust valves, ARP head studs, Injectors, 5v Bosch glow plugs, water pump, timing everything, serpentine everything,
New at 225k: new head, timing belt