Running cool?

GreenDieselEngineering · **Joined:** Sun Jun 07, 2009 5:10 pm **Posts:** 1111

The low coolant temps can effect fuel economy negatively for a few reasons:

1. At 130 F our tune switches from warm-up mode (twin pilot injections) to single pilot. This is a fuel saver.
2. Coolant temp corrections for injection timing, rail pressure, boost pressure, and pilot quantity are active up to around 160 F.
3. Low liner temps around the pistons tend to decrease fuel efficiency due to less fuel atomization.

Depending on where your coolant temps are at, one or more of the items above could be leading to less than stellar fuel economy. Do you have an OBD reader that can see the coolant temps off the bus?

LibertyCRD · **Posted:** Sat May 22, 2010 9:58 pm

No, I don't have a OBD reader. But the past 3 days, the Jeep has run at the second tick below half way on the temp. guage. Today I towed a boat and it moved up to almost half way mark. I really wish I knew if my jeep has had the temp guage recalibration...but either way running at that second tick below the half mark is not good, correct?

On the CRD I bought brand new...I don't recall it ever running at the half-way mark or higher during normal driving. But from what I'm reading, these things need to be running hotter than this.

stoutdog · **Posted:** Sat May 22, 2010 11:09 pm

LibertyCRD wrote:

No, I don't have a OBD reader. But the past 3 days, the Jeep has run at the second tick below half way on the temp. guage. Today I towed a boat and it moved up to almost half way mark. I really wish I knew if my jeep has had the temp guage recalibration...but either way running at that second tick below the half mark is not good, correct?

On the CRD I bought brand new...I don't recall it ever running at the half-way mark or higher during normal driving. But from what I'm reading, these things need to be running hotter than this.

One tick below halfway is normal. My money is on you having a dead thermostat.

Big Montana · **Posted:** Sun May 23, 2010 8:32 am

I would say that your thermo is dead or dying too. My Jeep new was always at half when driving. I just spent the last Michigan winter with the thermo gauge at one tick over a quarter. That's cold. My MPG isn't what it used to be by about 3-4 MPG. I know that I once got 28 pre-GDE driving to Washington D.C. Now I'm lucky if I can get 24.

Now that it's warm here, I have been using the AC in cold traffic and it causes my temp gauge to go up to about half. That's the only thing that seems to be warming my Jeep up. Not sure why.

I am waiting on the machined thermo's once they're ready because I don't want to pay for this thing again.

racertracer · **Posted:** Sun May 23, 2010 9:16 am

What is that TSB number?

BVCRD · **Posted:** Sun May 23, 2010 3:19 pm

stoutdog wrote:

LibertyCRD wrote:

No, I don't have a OBD reader. But the past 3 days, the Jeep has run at the second tick below half way on the temp. guage. Today I towed a boat and it moved up to almost half way mark. I really wish I knew if my jeep has had the temp guage recalibration...but either way running at that second tick below the half mark is not good, correct?

On the CRD I bought brand new...I don't recall it ever running at the half-way mark or higher during normal driving. But from what I'm reading, these things need to be running hotter than this.

One tick below halfway is normal. My money is on you having a dead thermostat.

Yesterday, it got pretty warm here(76*) and I noticed ours was indeed on the first tick below half.

Joe Romas · **Posted:** Tue May 25, 2010 3:50 pm

The TSB was for guages reading high as in too hot :pepper:

They were adjusted downward :mrgreen:

So it would definetly not help one showing low :SOMBRERO:

BVCRD · **Posted:** Tue May 25, 2010 4:15 pm

Joe Romas wrote:

The TSB was for guages reading high as in too hot :pepper:

They were adjusted downward :mrgreen:

So it would definetly not help one showing low :SOMBRERO:

Yea, I think ours is fine. It just reads slightly cooler than normal when we coast down a mountain and don't give it any fuel. Sometimes we get to coasting over 80 mph on a 3 mile long run. I think this is normal.

stoutdog · **Posted:** Tue May 25, 2010 5:42 pm

BVCRD wrote:

Joe Romas wrote:

The TSB was for guages reading high as in too hot :pepper:

They were adjusted downward :mrgreen:

So it would definetly not help one showing low :SOMBRERO:

Yea, I think ours is fine. It just reads slightly cooler than normal when we coast down a mountain and don't give it any fuel. Sometimes we get to coasting over 80 mph on a 3 mile long run. I think this is normal.

My bad, I thought it adjusted upwards. :oops:

BV, is that the only situation where your gauge drops below the 176* mark? If so, you are probably right.

BVCRD · **Posted:** Tue May 25, 2010 6:50 pm

stoutdog wrote:

BVCRD wrote:

Joe Romas wrote:

The TSB was for guages reading high as in too hot :pepper:

They were adjusted downward :mrgreen:

So it would definetly not help one showing low :SOMBRERO:

Yea, I think ours is fine. It just reads slightly cooler than normal when we coast down a mountain and don't give it any fuel. Sometimes we get to coasting over 80 mph on a 3 mile long run. I think this is normal.

My bad, I thought it adjusted upwards. :oops:

BV, is that the only situation where your gauge drops below the 176* mark? If so, you are probably right.

Yea, I think so. The other day I was just around town, not out on the highway and it was on the -1 tick mark. The thing heats up fast in the winter. My Mustang GT warms up in like 5 miles compared to 5 blocks with this thing.

stoutdog · **Posted:** Tue May 25, 2010 7:46 pm

BVCRD wrote:

Yea, I think so. The other day I was just around town, not out on the highway and it was on the -1 tick mark. The thing heats up fast in the winter. My Mustang GT warms up in like 5 miles compared to 5 blocks with this thing.

To me, that sounds like you're fine. My father's CRD has a bum tstat and it sits at about 150* when idling in traffic. It only climbs to 176* if he turns the AC on MAX... and, even then, it needs to be under some load.

LibertyCRD · **Posted:** Tue May 25, 2010 9:31 pm

Yeah...today it was 85 degrees here and the Jeep ran anywhere between half and the tick before half. I think it must be fine. Diesels are known to run cool which is why truckers use cardboard on the grille and why Jeep used a supplemental heater to begin with. I think I will keep running what I have.

LibertyCRD · **Posted:** Fri May 28, 2010 8:45 am

Wow. Just called the dealer to see how I can verify that TSB 08-043-05 was done to my Jeep to correct the temp. guage...and they said the ONLY way to know is to bring it in to the dealership and hook it up to the diag. tool. $89 to do it! :shock:

If my temp. guage ain't updated, it won't be getting updated.

mngoat01 · **Joined:** Wed Aug 06, 2008 11:25 am **Posts:** 67

LibertyCRD wrote:

Wow. Just called the dealer to see how I can verify that TSB 08-043-05 was done to my Jeep to correct the temp. guage...and they said the ONLY way to know is to bring it in to the dealership and hook it up to the diag. tool. $89 to do it! :shock:

If my temp. guage ain't updated, it won't be getting updated.

I got the exact(I mean exact) same statement from my dealer. Even the $89.

LibertyCRD · **Posted:** Wed Jun 02, 2010 1:12 pm

GDE needs to buy a StarScan tool and rent it out to us for like $20 per day or something.

Then we could find these things out on our own.

TJ2 · **Posted:** Tue Jun 08, 2010 4:34 pm

Well, my thermostat seems to be toast. I've done about 3,000 road miles (some offroad) in the last three months. It runs 'cool' in cold weather (one to two clicks below halfway) and the needle points at the halfway mark in warm (80+ degrees). That tells me the ambient air temp is regulating my engine temp. . . not the T-stat.

I'm wondering if others who post low miles/gal due to 'winter diesel' may have the same condition? Or, blame a GDE tune for not increasing the mpg? Whatever the case, this is a job that will wait until fall. Maybe by then an alternative to the 176 degree stock stat will be available???

LibertyCRD · **Posted:** Tue Jun 08, 2010 9:19 pm

TJ2 wrote:

Well, my thermostat seems to be toast. I've done about 3,000 road miles (some offroad) in the last three months. It runs 'cool' in cold weather (one to two clicks below halfway) and the needle points at the halfway mark in warm (80+ degrees). That tells me the ambient air temp is regulating my engine temp. . . not the T-stat.

I'm wondering if others who post low miles/gal due to 'winter diesel' may have the same condition? Or, blame a GDE tune for not increasing the mpg? Whatever the case, this is a job that will wait until fall. Maybe by then an alternative to the 176 degree stock stat will be available???

Well see, that is EXACTLY what mine does. On a cool day, it'll run two ticks below half. On a hot day it'll run at almost half. I just assumed that is normal. I mean....colder ambient air means the fluids and engine block, etc. will all be colder, therefore the engine will run cooler. Right? Seems like that should be expected. On a hot day, when the fluids are thinner and the engine block and head material is warmer, the engine will run warmer. But....I could be wrong.

CATCRD · **Posted:** Tue Jun 08, 2010 9:26 pm

LibertyCRD wrote:

TJ2 wrote:

Well, my thermostat seems to be toast. I've done about 3,000 road miles (some offroad) in the last three months. It runs 'cool' in cold weather (one to two clicks below halfway) and the needle points at the halfway mark in warm (80+ degrees). That tells me the ambient air temp is regulating my engine temp. . . not the T-stat.

I'm wondering if others who post low miles/gal due to 'winter diesel' may have the same condition? Or, blame a GDE tune for not increasing the mpg? Whatever the case, this is a job that will wait until fall. Maybe by then an alternative to the 176 degree stock stat will be available???

Well see, that is EXACTLY what mine does. On a cool day, it'll run two ticks below half. On a hot day it'll run at almost half. I just assumed that is normal. I mean....colder ambient air means the fluids and engine block, etc. will all be colder, therefore the engine will run cooler. Right? Seems like that should be expected. On a hot day, when the fluids are thinner and the engine block and head material is warmer, the engine will run warmer. But....I could be wrong.

The thermostat should keep the coolant temp almost constant regardless of outside temp. Mine does the same thing your guys' does- meaning it's defective. I'm also waiting on a thermostat alternative.

Running cool?

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