dewclaw

This is probably a no brainer ..but.... do these trucks tend to run cold ?

I have a '99, 4X4.

When I run my truck in cold weather, going downhill on a long grade , no throttle, the coolant temeprature pegs out LOW. Cold.

Is this normal or do I have a stuck thermostat ?

(I am STILL impressed with the massive cooling system in these trucks.)

Thanks in advance for the input.

DEW

__________________
98.5 4X4 , Quad cab, long bed ,white as can be , 5 sp. Edge chip , 4" exh , K&N , silencer ring gone, head-ache rack, purple haze light to light up the license plate, big fat mud flaps.

klx650a2

Do you have your radiator blocked off? Yes, these trucks run cold when not worked. When I had my 2000, I ended up replacing the thermostat. If you do that, only buy a original Cummins part, expensive but they work.

__________________
2007.5, 2500HD, QC, Laramie, 4X4, SB, 68RFE, 3.73, Inferno red, Edge Insight w/pyro, MaxBrake, Firestone Ride-Rites and controller, Air-Zenith air compressor, EZ Change Drain plug, S&B drop in air filter, 250 watt oil pan heater, EGR unplugged.

2008 YZ450FX, matching 756's, Marcel Fournier ice tires, 320mm EBC supermoto front disk, billet fuel screw, DiD narrow x-ring chain, Ironman sprockets, Scotts SS oil filter, Dr. D pipe coming, love the SSS suspension...

DIESELWRKS

you said 99 but below says 98.5. but anyway. if you have never replaced the thermostat or dont know if it has I would for safe measure. normally there is a 180 or 190 degree one. but if your going up and down I-5 up by like shasta with cold temps I can see a little colder but shouldnt be moving the needle drastic. check with the thermostat and go from there.

__________________
2002 HO 6-SPD LB 4X4 QC HTT 62/14, SB-DD3600, TST PM3/*REVO-BETA*SMARTY MACH 4'S, RINGED W/ STUDS, AFE/2 " FTE 6" STACK D/PRICOL GAUGES, FASS 150,1/2 DRAW-STRAW, DSS-BOX DT PRO-FAB TRAC BAR, CONV-T STYLE STEERING,DUNKS TRACTION BARS, AIR BAGS,17'' KMC BLACK HOSS, 37" TOYO MT'S 6" LONG ARM LIFT.THANKS RIP@sourceaumotive.

US.MARINE PROUDLY SERVED 1993-2006

dewclaw

Yea, its a 98.5, just rounding it off a bit. And you are right , Shasta / Trinity area.
My radiator isnt blocked off. This thing just should not peg out low , yep its probably stuck open a bit. I will go with Cummins a part.

Out of curiosity, what is the down side of of it running cold other than my cab heater puting out cold air ; ) Any performance issues ? I have seen big-rigs with their radiators covered so there must be perf problems when they are too cold ?

Dinner

Diesel engines are more efficient when warmed up to the proper temp. Everything is seated properly and the fuel/air is being compressed and burned properly. It's also easier on parts to have the engine all warm and cozy.

__________________
2001 Dodge Ram 2500 CTD QC SB 4X4: Goerend Trans with Billet Flex & Billet Input / Airdog 100 / Gauges / ScanGauge II / BHAF / Draw Straw / HTT Exhaust Manifold / 4" Straight to 6" Stack / Smarty & TST PM3 Comp Stack / DDP Stage 3's / HTT 62/71/14.

WestTN

When coasting downhill you are burning NO fuelat all. The engine is just pumping air through. So, it has to cool down some.

__________________
2001 2500 White long bed Quad Cab Sport ETH/DEE All options except 4WD, CD changer and Auto trans. Didn't want those!
144,500miles. Replaced lift pump twice. Geno's big line kit. Also replaced left license bulb. . First set of Michelins lasted 97,681 miles.

1-5-3-6-2-4

yes true. at no throttle coasting theres no fuel injected at all. but with low cylinder temp when you do inject fuel it is not a complete burn you will eventually glaze the cylinder wall. which will be bad. burning oil, loss of compression.......you just dont want that.

__________________
Luke
---------------------------------------------------
'97 Chevy V3500 CC DRW 6BT 22" Alcoas
'98.5 24v 2500 QC 5spd 4wd Demon hot-rod *sold*
'90 VW Jetta 1.6L oilbrnr 5spd coupe wolfsburg
'73 RS/Z-28 Survivor.

dewclaw

I just ordered a new 'stat' from Cummins West. (180'F)

Dodge dealer wanted $72, ???????? Thanks but no thanks Dodge.

Cummins sold it to me for $33, shipped to my house.

bamadzl

This thread caught my eye. Mine's always run cold like that. I replaced the tstat and it performs the same. Either mine just runs cold or the sending unit or gauge is off.

Brad

__________________
99 Ram 2500 CTD 4X4 QC Long Bed, 47RE w/ Goerend parts and 3 disc TC, Smarty, Jammer 5's, II PS62/12, Dipricol Pyro, Boost & FP gauges, Homemade Walbro Fuel System, Amsoil 4510 air filter, 4" Exhaust w/ Donadson M085171 muffler, 3.55 gears, 285/75/16 Goodyear Silent Armors, Westin step bars, GM 1 Ton Wheel Cylinders, LarryB's Starter Contacts, Bilsteins, 300k miles and counting.

jrv15

so whats a good temp? mine runs about 160

__________________
99 QC LB 24V DRW
TRAIN HORN, EDGE EZ, SINGLE TO DUAL EXHAST 4"

forwardho

190-200 on my truck is normal.

__________________
2004.5 Dodge Ram 3500 Quad Cab SLT
AKA Blue Thunder
48RE Trans w/Mag-Hytec DD Pan @ Temp Gauge
Rhino Bed Liner/Westin Nerf Bars
18K Reese Signature Hitch
Viper Security System
50-Gal Aux. Fuel Tank

2003 35' Cardinal Fifth Wheel -AKA Motel 9

dewclaw

put a 180 in mine. Found that the old stat had one side of the 'perch' that holds the spring, cracked in half . Holds solid at 180 now. It does seem to run more efficiently now.
By the way, I just turned 300K miles on the truck today ; )

jrv15

ok im scared now... my truck usually runs just above the 145 mark all the time. is this bad?????

nickg

throw a new thermostat in and all should be golden, usually if they run cols the thermostats opens too soon, engine is more efficent when up in the 180-190 range. mine runs 190+ all the time except in extreme cold temps does it cool down,

__________________
Nick

2001, 2500 Edge J/A Hot unlocked,Magna flow exhaust. HX35 Jammer II's. BHAF, Airdog 150,DSS,3rd gen Track Bar. Carli Suspension, 3rd gen Brake upgrade, transgo Shift Kit. Firestone AirBags May 07 297,000kms Dec/09 473,000kms RETIRED Military Mechanic (20yrs)

jrs_dodge_diesel

3 possibilities come to mind:

1- you are driving short trips and the engine does not have time to warm up.

2- If the radiator is not blocked off, it will take longer for the engine to warm up (do this when it gets cold and stays cold outside)

3- you might have possible thermostat and sensor issues

1 and 2 can affect each other. Short trips, cold air, and an open radiator will definitely make the engine take a lot longer to warm up.

Try this, drive your truck around for about a 1/2 hour and see if it comes up to temperature. Even when it is 40ºF outside, my truck will come up to full temperature with an open radiator (takes a little longer but it will).

If it still does not warm up then start looking into possible thermostat issues.

If you have never blocked off the radiator, it's pretty easy. I personally use a large sheet of cardboard, and slide it in between the intercooler and radiator. Works good, and I've been able to use the same piece of cardboard for 2 years now.

Good luck, and let us know what you find.

__________________
J.R.
U.S. Coast Guard , Electronics Technician 1st class
Extra class Amateur radio operator - K5DTR

2001½ SLT 2500
2WD, auto, short bed

Hi-flow banjo bolts
Scotty Air II with the cowl hole and no silencer ring !
Isspro EGT (pre-turbo),fuel pressure, boost, and transmission temperature (sensor in hot line) guages