Another GDE Feature

DOC4444 · **Posted:** Sun Dec 13, 2009 2:58 pm

GDE now offers recalibration of the viscous heater shutoff temp. For those of you not familiar with the VH, it facilitate faster warmup, but runs pretty much all the time with the OEM ECU during the winter. Our experience is that it costs a full 3 MPG. The only option before to avoid this MPG penalty was to run with the VH relay removed. With a grill blanket, this was not too bad, but GDE now offers an even better alternative.

With the setting I have, the VH clutch engages at startup and disengages one "tick" below the "one quarter" mark on the instrument cluster temp gauge (recalibrated as per TSB).

This translates to about 5 minutes of drive time from cold startup during a typical NE winter day. Since fuel mileage is pretty horrible until the motor warms up, I think this is a good compromise. However, GDE can program your ECU to shut off your VH at pretty much whatever coolant temp you would like.

DOC

mikey1273 · **Posted:** Sun Dec 13, 2009 4:56 pm

Since the change to winter blend my MPG went down some, now that its in the 30's and less most days its even lower, that adds another reason for me to consider saving up for the GDE ECO tune.

One question how does the VH work to create heat???

DOC4444 · **Posted:** Sun Dec 13, 2009 5:13 pm

Try removing the VH relay to see how much the VH is negatively impacting your mileage, though I would suggest a grill blanket to help compensate for slower warmup.

All I know about VH operation is that it creates friction/heat which is transferred to the coolant. It is on the upper left of the front of the motor when viewed from the front. It looks a lot like an AC compressor and is operated similarly with an electrically controlled clutch. (You can see whether it is engaged by checking for movement of the front of the pulley.)

DOC

mikey1273 · **Posted:** Sun Dec 13, 2009 6:26 pm

So that could also be why it feels like it has a lot less power when its cold too :idea:

Is the relay right on the VH?

DOC4444 · **Posted:** Sun Dec 13, 2009 6:54 pm

The VH relay is in the "power distribution center" (fuse box for regular folks) under the hood. Its location is noted on the bottom side of the lid. You will probably need a pair of needle nose pliars to pull it straight out. (It is a pretty tight fit.) I think a noticeable power loss would have to be more than just the VH. BTW, a lot of winter diesel can be 30% kerosene which has less energy than diesel.

DOC

mikey1273 · **Posted:** Sun Dec 13, 2009 7:42 pm

I may be exagerating when I say "a lot less" but I notice it is not as zipppy as it was when I first got it in the summer. both togther could have the effect I am feeling in the mileage and power. I have to check that relay out in the daylight.

danoid · **Posted:** Tue Dec 15, 2009 1:07 pm

There are a host of issues why things are less zippy in the cold...

75W140 gear lube in rear axle
ATF in transfer case
ATF in transmission
5W40 oil in engine
oil in hydraulic fan decoupler

All are significantly thicker at 0°F than at operating temperatures greatly increasing drag.

Tire rubber is stiffer, sometimes you can even feel the flat spots that remain after sitting overnight.

The torque converter will not lock up below a transmission sump temperature of (I think) 65°F.

Higher alternator loads (heated seats, headlights, fuel heater if anyone still has that connected, rear defroster, etc.).

and probably 50 other things.

geordi · **Posted:** Tue Dec 15, 2009 2:56 pm

Speaking of differential gear oil, I'm toying with the idea of draining mine and refilling it during the Christmas holiday downtime.

What are acceptable / preferred replacement fluids, and is there anything specific I should know about doing these? Bear in mind, I have NEVER done this before on any of my vehicles. I know there is a schedule for the CRD, and I have probably exceeded it, which is why I'm thinking about doing it. I'd also like to reduce the viscosity within the accepted range of information here, to increase the mileage if at all possible.

Y'all know what I use my truck for, what would you suggest for a replacement fluid? Are there any filters? Any specifics on technique / fill level?

RTStabler51 · **Posted:** Tue Dec 15, 2009 3:25 pm

geordi wrote:

Y'all know what I use my truck for, what would you suggest for a replacement fluid? Are there any filters? Any specifics on technique / fill level?

I used Royal Purple, no real reason why. Most on here will probably tout Amsoil products.

grywlfbg · **Posted:** Tue Dec 15, 2009 4:11 pm

I've used Amsoil Severe Gear 75W-90 for 80k miles now. I do some very light towing (6x10 covered trailer hauling motorcycles) but otherwise the wife uses the CRD for commuting.

I have also added the PML diff cover on the rear which adds a little more fluid and provides a drain plug for easier changing. There's a thread in here about the covers.

CRD_Joe · **Posted:** Tue Dec 15, 2009 8:19 pm

I use Amsoil as well. Hey, speaking of that grill blanket. Where can I find one of those???

tigafila · **Posted:** Tue Dec 15, 2009 9:53 pm

I use Amsoil also. As far as tips, front diff seems to almost have to be filled with a suction gun, rear is much esier to get to. Tigafila

Tinman · **Joined:** Mon Apr 10, 2006 10:45 am **Posts:** 308

This is a good example of why I wish GDE would do what every it took to make a downloader to sell. That way, current customers could download updates and up load to ECM. With a ECM swap, this isn't an option for previous customers.

mikey1273 · **Posted:** Thu Dec 17, 2009 12:45 am

I would love a downloader tool. That way I would not have to swap my ECU for one that was someone else's that they reprogramed. being that I work with computers for a living I am sure I could handle the updating my ECU.

VMKJCRD · **Posted:** Thu Dec 17, 2009 1:44 am

mikey1273 wrote:

I would love a downloader tool. That way I would not have to swap my ECU for one that was someone else's that they reprogramed.

x2 That would be a good idea. But they would have to come up with a software for only the people with GDE tuned ECUs could download the software from their website and maybe also using the same software to upload it to the Crds.

Glend · **Posted:** Thu Dec 17, 2009 2:44 am

Here here for the downloader tool. Potential overseas customers of GDE are just plain out of luck under the current software distribution method.

kdlewis1975 · **Posted:** Thu Dec 17, 2009 10:19 pm

RTStabler51 wrote:

geordi wrote:

Y'all know what I use my truck for, what would you suggest for a replacement fluid? Are there any filters? Any specifics on technique / fill level?

I used Royal Purple, no real reason why. Most on here will probably tout Amsoil products.

I use the Mobil 1 axle lubes...mostly because it was the easiest and most abundant synthetic to find in the auto store. I put 75w90 in the front and 75w140 in the rear. With it being winter, it may be justifiable to switch it to the lower viscosity.

Hopefully Santa gets this for me, but if you want a relatively inexpensive diff cover with a drain plug:

http://cgi.ebay.com/ebaymotors/Mopar-Ch ... 500wt_1182
http://stores.hi-potek.com/-strse-1/Chr ... Detail.bok

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