Engine/Transmission (1998.5 - 2002) 180° thermostat increased mileage

[RustyJC]

Ignoring the injection timing issue Marco mentioned, from a purely thermodynamic standpoint, a higher coolant temperature should give better mileage. That's because there's less loss of compression and combustion heat (i. e. , energy) to the cooling system at 190 degF versus 180 degF since the thermal gradient between the charge and the cylinder walls is lower at 190 degF, so more heat (which increases pressure) is available to generate power during the expansion stroke.



If, however, the computer advances injection timing at 180 degF as Marco states, then the fuel economy gains due to the advanced timing may override the fuel economy loss due to increased heat transfer to the cooling system.



Rusty

 

[LSMITH]

Ron, the thermostat has a U-channel type of O-ring around the outside that seals it between the block and upper radiator hosebarb. I have not been able to get one seperately, that is all that is wrong with the thermostat I took out of my truck. The good parts guy at Cummins told me that they are not sold seperately anymore.



That^^^^^^^^^^ is what I mean when I said I need a gasket. I reused my thermostat too, and eventually it leaks. I am guessing that the gasket is a one compression type of affair. Hope yours doesn't start to leak, but don't be surprised if it does.

 

[PRout]

Just checked mileage.



18. 8 mpg



Seems about normal.



Its kind of a bad test using mine, because I also lost the muffler a few weeks ago, so 2 things have been changed recently. I got 19. 1 on the last tank (after removing the muffler, before changing the thermostat).



Normal before changes was 18. 5, so from removing the muffler & going w/ the lower temp therm, gave about . 3 mpg on this run. Will need more time since it needs some good miles to get an average.



Id say that the motor sure runs cooler, and theres definitely less heat radiating up through the floor board. Also, since they say heat is directly proportional to wear rates, the motor may last longer (if thats really an issue).

 

[Gray Ghost]

I picked up coolant and a new tstat today from Southern. It is a 180 deg. I have logged every gal that has gone in that truck since day one. I drive 120 miles everyday, so in a week or so, I will know what a 99 24v is doing. I will keep you posted on my milage.

 

[pwr2tow]

Gray Ghost,

excellent, I look forward to hearing what the out come is. I don't have any time for awhile to do the t-stat swap or research myself. Please keep us posted, it will interesting to see how the outcome is compared to others, with the amount of miles you put on and the same miles every day should make for a very good result.



Ron

 

[RCapps]

Hey Lazy Boy...



Was wondering about your transmission mods...



I just put a BD X T/C, V/B, and Press Loc in my 1996 along with a 250 fuel plate. I notice that when under light throttle and when the transmission locks the converter in OD (approx 45mph) the pressure loc will rotate the throttle a smidge and accelerate the truck. The foot pedal moves down approx. 1/2 inch when the press loc kicks in. Does yours do this? Was just wondering if this is normal for the press loc. Thanks...



Your truck sounds like it is a goer!!!!!



RCapps

 

[RCapps]

Oops!!!



Meant last message to go to ronsram1999!!



Sorry 'bout that... . guess I have to get smarter than the 'puter



RCapps

 

[Steve Campbell]

Hey Marco

If a person has a :VA, EZ, Pulse, etcetera,(which already advance the timing) will the ECM still advance the timing more if one puts in a 180 thermostat?

 

[pwr2tow]

RCapps,

Yes mine does, it is normal. What happens is when the pressure lock engages is it takes pressure off the throttle so the peddle feel is lighter and your foot has to compensate for a lighter throttle. I know it is not a very technical explaination but in essence that is what is happening.



Ron

 

[Gray Ghost]

Go Figure

Well I put the new Tstat in yesterday along with 4 gal of FleetGuard antifreeze. The old tstat said 180 and the new one said 180. Old one ran an RCH below the 190 mark. The new one is setting in the middle between the first mark and 190.

Don't know if the old one was marked incorrectly or just junk, but it ran that way from day one.

I will list the prior 5 tanks, This tank which has 215 miles on old tstat and 5 tanks with new tstat.

I will let you know in a couple of weeks

 

[Chace TX]

What do they come with?

My 01 runs at 180 or so. Dads 02 runs straight up at 190. His pickup only has 200 miles on it, but I don't remember mine running warmer when new. First tank on his (purchased Sat. ) was really burning the fuel, don't think it was due to running temp, just being new.

 

[WadePatton]

I just installed a 180. I like the new temps. Methinks the mileage difference can only be attributed to the reduced engagement of the mighty fan.



I've logged 6500 miles at 18. 9 average MPG on the 190. I'll post back when I have 2 or 3k on the 180--if I can do that before the BOMBS land.



Stock 24v, BHAF (recently installed), no muff, and 180.

 

[jgil104]

180*

i installed a 180* stat on mine[3500quid eth 01. 5] because my horton fan kept turning on @195*[on truck since new in 9/00along w/jake brake]

installed fr cummins 180*stat, very seldom hear horton fan and this with a 36' tri axle 5er triple slide on the way back fr porto vertta mexico w/ac on . and when running solo temp almost never goes over 185*even on 90* days

my mpg solo is around 20. 5 mpg/ towing 10. 5-12. 5mpg

 

[GeneralMachine]

Fan Clutch

Im going with the fan not pulling as often for the better fuel milage, For I am in the process of changeing the 190 to the 180, my fan come's in hard around 195. Harv

 

[Crazy Horse]

Here is some related info ( Thermostat Info )on the thermostat issue I thought was interesting. Some say the 180 is faster to open. For the start and stops 10-15 mile trips it makes sense milage way improve for the short trippers due to the possibility of getting up to operating temp faster. I've been thinking about changing mine out just to keep all the Engine/Transmission temperatures down especially when towing.

 

[hammersley]

How much

What does cummins charge for a thermostat? On the site that Crazy horse referenced, it was mentioned that the folks at Cummins would only sell you a thermostat for the year the vehicle was built i. e. if your 2001 came with a 190, then that's all they'll sell you. Folks mentioned an emission compliance issue. Has anybody else had that problem?

 

[Mark_Kendrick]

I walked into Cummins and asked for a 180* thermostat for a 24v ISB 5. 9.



that's what I got. <=$20

 

[1tuffram]

For those of us who live in cold country and DO NOT tow anything would it be best to stick with the 190 t-stat on an 2002 ETH??

 

[K_Arts]

Originally posted by 1tuffram

For those of us who live in cold country and DO NOT tow anything would it be best to stick with the 190 t-stat on an 2002 ETH??

I am going to change mine out for a 180* as soon as I do a coolant change. My truck constantly runs at about 195* around town with no load... and my fan clutch doesn't seem to lockup to keep my motor cool, so I figure that the 180* will help out some.



As far as the cold season goes. I've never had a problem with my engine not warming up in winter so you should be fine.



Kev

 

[Mark_Kendrick]

Originally posted by 1tuffram

For those of us who live in cold country and DO NOT tow anything would it be best to stick with the 190 t-stat on an 2002 ETH??

I'll assume that an '02 is the same as an '01 and say that my ETH liked the 180* tstat.



MY MPG has dropped off recently due to the nut behind the wheel having a lead foot and showerhead injectors