| LOST JEEPS http://www.lostjeeps.com/forum/phpBB3/ |
|
| Low temp readings and poor fuel mileage http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=73873 |
Page 1 of 2 |
| Author: | tomasnc [ Thu Jan 24, 2013 5:19 am ] |
| Post subject: | Low temp readings and poor fuel mileage |
The stuck open t-stat is a known problem. I have a spare engine from my first CRD that a rolled so I am going to pull that thermostat and install it on my current CRd. This car get poopy mileage 14-15 around town. The stat never moves above 1/4. My old CRD got 19 around town and the gage read 1/2. Opinions please. Thanks guys! Tom |
|
| Author: | racertracer [ Thu Jan 24, 2013 6:27 am ] |
| Post subject: | Re: Low temp readings and poor fuel mileage |
1. Replace the air filter if it's past due, diesels need to breath and air deprivation it will cause bad mileage. 2. Replace the fuel filter if it's past due, a dirty filter will cause bad mileage 3. Swapping out thermostat does not improve mileage... it is hardly noticeable. Many who have done it, reported no change in mileage, including me ...... done it twice now. 4. Run the jeep with the MAF sensor unplugged, it will turn the engine light on but will not hurt, or you can get a GDE tune. 5. Check to see that your brakes are not locking up, the pins may need lubrication. |
|
| Author: | dirtmover [ Thu Jan 24, 2013 9:37 am ] |
| Post subject: | Re: Low temp readings and poor fuel mileage |
racertracer wrote: 3. Swapping out thermostat does not improve mileage... it is hardly noticeable. Many who have done it, reported no change in mileage, including me ...... done it twice now. Eh? Swapping a bad thermostat certainly does make a different. Here's the data to prove it:  My previous stat was bad for most of 2011 resulting in a curve that is about 10% lower than the other years. Incidentally I added the GDE tune in Sept last year. You can clearly see the improvement. |
|
| Author: | tomasnc [ Thu Jan 24, 2013 11:55 am ] |
| Post subject: | Re: Low temp readings and poor fuel mileage |
The temp gauge on this CRD barley ever moves above 1/4 like I previously mentioned. Air & fuel filters are new, < 3 moths old. Brakes, Racetracer the MAF stills connected. When you speak of pins are you meaning the pins/rods the calibers slide on?. Thank you dirtmover for your input too. |
|
| Author: | kjjet [ Thu Jan 24, 2013 2:24 pm ] |
| Post subject: | Re: Low temp readings and poor fuel mileage |
Wow....thats alot of work to swap a used thermostat. I think thats not a good choice. Why? I and several others have reported after the thermostat has no fluid in it, (Dry for a time) the thermostat goes bad and only gets the engine temp to 1/4. What should you do? 1. Replace with new OEM. Or 2. Install a inline 195 deg thermostat. There are several posts on installs. It only takes 1/2 hour and less than $15. See post ..viewtopic.php?f=5&t=64333 |
|
| Author: | tomasnc [ Thu Jan 24, 2013 3:54 pm ] |
| Post subject: | Re: Low temp readings and poor fuel mileage |
My first CRD has a good T-stat. I'm going to try the in-line and see where that takes me. WOW, the in-line t-stat thread is very long ... 10 pages! |
|
| Author: | racertracer [ Thu Jan 24, 2013 5:03 pm ] |
| Post subject: | Re: Low temp readings and poor fuel mileage |
dirtmover wrote: racertracer wrote: 3. Swapping out thermostat does not improve mileage... it is hardly noticeable. Many who have done it, reported no change in mileage, including me ...... done it twice now. Eh? Swapping a bad thermostat certainly does make a different. Here's the data to prove it: My previous stat was bad for most of 2011 resulting in a curve that is about 10% lower than the other years. Incidentally I added the GDE tune in Sept last year. You can clearly see the improvement. You can produce all the charts you can get....... i can tell you from experience on 2 CRD's and my own hand calculations, that swapping out a failed Tstat with a new, didn't make a bit of difference on MPG. That is with a GDE tune and without. |
|
| Author: | dirtmover [ Thu Jan 24, 2013 7:27 pm ] |
| Post subject: | Re: Low temp readings and poor fuel mileage |
racertracer wrote: i can tell you from experience on 2 CRD's and my own hand calculations, that swapping out a failed Tstat with a new, didn't make a bit of difference on MPG. That is with a GDE tune and without. Well there you go. My experience and that of many other members is the opposite. You're misleading the OP by suggesting that the majority consensus/observation is incorrect. Yes, there are many other reasons for poor mpg and a failed stat is one of them. |
|
| Author: | racertracer [ Thu Jan 24, 2013 8:16 pm ] |
| Post subject: | Re: Low temp readings and poor fuel mileage |
dirtmover wrote: racertracer wrote: i can tell you from experience on 2 CRD's and my own hand calculations, that swapping out a failed Tstat with a new, didn't make a bit of difference on MPG. That is with a GDE tune and without. Well there you go. My experience and that of many other members is the opposite. You're misleading the OP by suggesting that the majority consensus/observation is incorrect. Yes, there are many other reasons for poor mpg and a failed stat is one of them. I am not going to get into a pissing contest. Misleading.... I meant what I posted and it comes from experience. Who are you the Pope? |
|
| Author: | SmokyCA [ Thu Jan 24, 2013 8:28 pm ] |
| Post subject: | Re: Low temp readings and poor fuel mileage |
A working thermostat should definitely improve mileage vs an open failed one. (The difference between a working stock t-stat and a non-stock higher-temp version is probably not great.) As I understand it, the motor will run richer at lower operating temps which will kill your efficiency. Also, if the temp is never getting above the threshold for the viscous heater to release, then that will drag on the engine as well, unless that viscous heater has a separate thermostat (?). The fuel filter, though...how would that cause poor mileage? If less fuel is able to get through a gummy filter, you'd have less power available which would, if anything, increase mileage by crippling your lead foot. Right? |
|
| Author: | dirtmover [ Thu Jan 24, 2013 8:49 pm ] |
| Post subject: | Re: Low temp readings and poor fuel mileage |
racertracer wrote: I meant what I posted and it comes from experience. It's all fine and dandy posting your "experience" or "gut feelings" but unless you can provide some empirical data to back it up it's all pretty meaningless. I meant what I posted and it comes from real measurements over an extended period rather than just a casual observation. |
|
| Author: | racertracer [ Thu Jan 24, 2013 8:57 pm ] |
| Post subject: | Re: Low temp readings and poor fuel mileage |
dirtmover wrote: racertracer wrote: I meant what I posted and it comes from experience. It's all fine and dandy posting your "experience" or "gut feelings" but unless you can provide some empirical data to back it up it's all pretty meaningless. I meant what I posted and it comes from real measurements over an extended period rather than just a casual observation. Sure looks great on paper but it doesn't work.... not in our rigs anyway. |
|
| Author: | dirtmover [ Thu Jan 24, 2013 9:11 pm ] |
| Post subject: | Re: Low temp readings and poor fuel mileage |
racertracer wrote: Sure looks great on paper but it doesn't work.... not in our rigs anyway. Whatever 
|
|
| Author: | CATCRD [ Fri Jan 25, 2013 12:48 am ] |
| Post subject: | Re: Low temp readings and poor fuel mileage |
racertracer wrote: dirtmover wrote: racertracer wrote: i can tell you from experience on 2 CRD's and my own hand calculations, that swapping out a failed Tstat with a new, didn't make a bit of difference on MPG. That is with a GDE tune and without. Well there you go. My experience and that of many other members is the opposite. You're misleading the OP by suggesting that the majority consensus/observation is incorrect. Yes, there are many other reasons for poor mpg and a failed stat is one of them. I am not going to get into a pissing contest. Misleading.... I meant what I posted and it comes from experience. Who are you the Pope? In God we trust...All others bring data. |
|
| Author: | flash7210 [ Fri Jan 25, 2013 9:10 am ] |
| Post subject: | Re: Low temp readings and poor fuel mileage |
I think everyone is going to have different experiences based on local climate and driving habits. I added the 195deg inline t-stat in July when I did my t-belt. My fuel mileage actually went down from 26 to 25 mpg.  But then again my mileage always goes down in the dead of summer. Now that its colder outside I'm getting 27-28 mpg.  Here in FL we dont get winter diesel fuel, I dont use the block heater, and I have no problems starting the engine on those rare mornings where it gets below freezing. 
|
|
| Author: | kjjet [ Fri Jan 25, 2013 10:05 am ] |
| Post subject: | Re: Low temp readings and poor fuel mileage |
First of all the engine should run at 1/2 not 1/4. I think we all agree on that! So regardless if you beleve the fuel millage will increase or not it should be fixed. I did get better fuel millage after installing a 195 deg inline stat + the engine runs with more power. You can feel it. |
|
| Author: | dirtmover [ Fri Jan 25, 2013 10:27 am ] |
| Post subject: | Re: Low temp readings and poor fuel mileage |
OK, if it makes anyone feel any better I can make it look as though my stat change made things worse: - I had noted low temperatures since Jan 2011. - I replaced the bad stat on the 7th Nov 2011. - The 3 fill-ups leading up to the change resulted in an average mpg of 22.07 - The 3 fill-ups following the change resulted in an average mpg of 21.87 There you go, I was wrong, I admit it. Changing the bad stat results in lower mpg! OTOH 7 years of data shows that my mpg is traditionally falling in Nov as the temperature drops and they switch over to the winter blend. You need to look at the big picture to see whats really happening 
|
|
| Author: | tomasnc [ Fri Jan 25, 2013 6:48 pm ] |
| Post subject: | Re: Low temp readings and poor fuel mileage |
I am tempted to try the in-line t-stat and go from there. I have had this car for three months and 16 MPG is the best I am getting
|
|
| Author: | ATXKJ [ Sat Jan 26, 2013 9:48 pm ] |
| Post subject: | Re: Low temp readings and poor fuel mileage |
T-stat won't hurt (mine added ~ 1 mpg) but 16 is way off - totally stock mine was 23 intown with lift/ARB/MT's - it dropped to 20. the dragging calipers have been on all Liberties - not just CRD - as have worn front bearings have you checked tire alignment? |
|
| Author: | Big Montana [ Sat Jan 26, 2013 10:44 pm ] |
| Post subject: | Re: Low temp readings and poor fuel mileage |
dirtmover wrote: racertracer wrote: 3. Swapping out thermostat does not improve mileage... it is hardly noticeable. Many who have done it, reported no change in mileage, including me ...... done it twice now. Eh? Swapping a bad thermostat certainly does make a different. Here's the data to prove it: My previous stat was bad for most of 2011 resulting in a curve that is about 10% lower than the other years. Incidentally I added the GDE tune in Sept last year. You can clearly see the improvement. I agree with all of this too. New thermo and GDE tune improved mine as it did yours. |
|
| Page 1 of 2 | All times are UTC - 5 hours [ DST ] |
| Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group http://www.phpbb.com/ |
|