I bought my CRD used in Nov '06 with 14,621 miles. The best fuel economy I have ever gotten was about 27mpg. I had a used tracklok installed at 18.5K and oil was replaced with synthetic 75w/145. I took the Jeep in a couple of weeks ago to have the pinion seal replaced. The tech replaced the pinion seal and an axle seal and reported the differential had water in it I don't think I have driven through water deep enough to get water in the differential. 300 miles later the differential was howling, took it back. Nine days later I got the CRD back with new pinion bearing and seal, axle bearings and seals. The tech first replaced the pinion bearing and right axle bearing, found the diff was still noisy and replaced the left bearing. So the differential oil was changed twice this repair. Yesterday I drove to Leavenworth, KS and back. The reserve light came on at about 560 miles. I will be able to make 600 miles on a tank of fuel for the first time. Could the differential bearings make that much difference in fuel economy?

Lewis

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Mail Rated 2005 Red CRD Sport with large rectangular hole in top right behind the EVIC and above the heated leather seats.
2004 Jetta TDI

75w/145 Seem like very a heavy lube if you aren't doing heavy towing, especially for synthetic. Did the mechanic put that same weight back in?

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Manure green 2005 CRD sport4x4, GDE Hot tune, Cat Gut, OE skids, Draw tight hitch, Duramax lift pump, 160K on multiple varieties of fuel, XM radio, Escort live with Redline, fog light mod, GPS, Icom IC7000 all band radio call sign KC9QPF, Grabber AT2s on Soft 8s, FIA grill blanket.

Yes they can.

I am sure it is. They used Mopar 4874469. I have towed heavy loads a couple of times, look at my avatar.

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Mail Rated 2005 Red CRD Sport with large rectangular hole in top right behind the EVIC and above the heated leather seats.
2004 Jetta TDI

Timken claims "up to a two percent gain in vehicle fuel economy" for their "Fuel Efficient Bearings". These bearings don't look like they are replacements that can be slapped into an existing axle or differential.
http://www.timken.com/en-us/products/be ... cient.aspx

2% percent of 27 MPG is a little over 1/2 MPG.

I managed to go 605 miles on 19.5 gallons of fuel, about 31 mpg. I would have expected 26-27 mpg based on past history. This makes me wonder if many CRD owners are suffering from parasitic drag somewhere in the drive train. I tend to drive very smoothly and limit brake usage, but could not get good fuel economy till this tank.
Lewis

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Mail Rated 2005 Red CRD Sport with large rectangular hole in top right behind the EVIC and above the heated leather seats.
2004 Jetta TDI

I have been having similar experience for about 6 months. Economy is down even though I've been driving like a hypermiling grandma... If you're not hearing any noises, how can one check for parasitic drag, though, unless it's the brakes?

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2005 Silver CRD Limited
245/75R16 GoodYear Duratracs
Fumoto drain | ProVent CCV Filter
Stanadyne FM100 filter | Cummins fuel pump
GDE Eco | SEGR | BoulderBars | FrankenLift | Frankenskids

If the pinion bearing were causing a 2% fuel economy loss the heat that it generated would be very high. I can put my hand on all parts of my differential after cruising for a while on the hwy and it is barely warm.

dgeist. If you suspect parasitic friction loss from your breaks. put your hands on the center of the wheel after driveing down the Hwy for 5 minutes. If you can keep your hands there the breaks are not dragging.

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Manure green 2005 CRD sport4x4, GDE Hot tune, Cat Gut, OE skids, Draw tight hitch, Duramax lift pump, 160K on multiple varieties of fuel, XM radio, Escort live with Redline, fog light mod, GPS, Icom IC7000 all band radio call sign KC9QPF, Grabber AT2s on Soft 8s, FIA grill blanket.

As nursecomo said there should be heat. Until a couple of weeks ago I had very little noise. That said, if the truck was set on jacks and the transmission and transfer case were put in neutral, torque required to start wheels spinning might give some indication. Or spin axle to a set rpm and time till stop and compare to a good mileage CRD. Anybody have any ideas how to compare?

Lewis

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Mail Rated 2005 Red CRD Sport with large rectangular hole in top right behind the EVIC and above the heated leather seats.
2004 Jetta TDI

Good bearings and seals, along with proper lubrication, can make a noticeable difference in MPG with an efficient engine such as our diesel.

Month or so ago, based on what I was hearing online and from Ranger1, I replaced the driveshaft u-joints with greaseable Gold Seal units from Tom Woods Custom Driveshafts. So far, on the first full tank since replacing them, fuel mileage in mixed driving looks to be noticeably improved. Also got rid of any clunk and jerk when shifting between reverse and drive, or between drive and neutral at a long stoplight - driveline feels nice and tight.

Synthetic lube and lube weight does make a difference, often not noticeable on an internal combustion vehicle. On an electric pickup I have - an '81 Ford Courier/Mazda B2000 - factory lube in the manual tranny and rear end was 90 weight conventional oil. I switched it over to Redline 75W90 MTF and Redline 75W90 Gear Oil in the rear end. That reduced power consumption from the battery pack by nearly 25% on my work commute. Also, when I first obtained the vehicle, the previous owner had replaced the driveshaft and hadn't bothered to balance it, such that it wouldn't even coast downhill and had a bad vibration over 50 mph. After a proper balance job, it would coast forever and range on a battery pack charge dramatically increased.

In short, yes, some attention to the driveline after the transmission will make a difference.

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Mitchell Oates
'87 MB 300D Diamond Blue Metallic
'87 MB 300D - R.I.P. 12/08
'05 Sport CRD Stone White
Provent CCV Filter/AT2525 Muffler
Stanadyne 30 u/Cat 2 u Fuel Filters
Fumoto Drain/Fleetguard LF3487 Oil filter
V6 Airbox/Amsoil EAA Air Filter
Suncoast TC/Shift Kit/Aux Cooler
Kennedy Lift Pump/Return Fuel Cooler