How long does it take to bring the engine to normal operating temp after start in the morning? I am driving around 10 - 15 miles but the temp is still only 185 degrees (instead of 205 when fully warm).

Outside temp during test drive is approx. 60 degrees. How do I test if one of the thermostats is stuck open?
Thanks for your input.

Your thermostat is probably fine it takes longer for a diesel to warm up.

I found in the cooler weather if you drive it hard it goes to full operating temp. If you drive it easy it may only hit 180degrees. I've been keeping it at 65 on the highway and in the morning (40 to 50 deg) it only hits 180 in 27 miles.

I drive my truck easy until the oil pressure drops down to about 60, then I'll romp it. On a cold morning like today, where it was 26 out, I started it and let it idle for bout 10 minutes. After that it took about 5 miles of interstate driving to get up to 160, according to Attitude display. The dash gauge is useless in my opinion.

Maha

185 is where the first stat starts to open, under light load, cold day, that's where it will stay until she produces more heat. So 185 is considered operating temp, with 205 at the upper end of that, with the second stat fully open.

My truck seems to be the same way, it might get up to 165 or so in about 20 min. The thing is I drove the truck yesterday morning it was probably about 25 degrees out. I let it warm up for 15 min and drove another 15 to work and the heater was barely putting out any heat when I got to work. Is this the norm or do I have something to be concerned about. 04 lly

Thanks for all the good infos! So nothing wrong with my truck - I am happy!

My truck seems to be the same way, it might get up to 165 or so in about 20 min. The thing is I drove the truck yesterday morning it was probably about 25 degrees out. I let it warm up for 15 min and drove another 15 to work and the heater was barely putting out any heat when I got to work. Is this the norm or do I have something to be concerned about. 04 lly
I think it's normal. My truck takes freakin' FOREVER to warm up too. Diesels are just so dang efficient.

A winter cover should help a bunch. I bought one off of Duramaxdad (thanks again!!!)... just haven't had the time to put it on yet. I think that's going to be this weekend's project, along with finishing my Christmas shopping...

I drive about 15 miles to work. This morning I started it and drove without warming it up(outside temp 28F) and it hit 185 within the first 5 miles and it does that pretty regularly regardless of outside temp. I haven't seen temps below 26 degrees F yet this year, but I am going to Mass for the holidays and will see how it responds to colder temps. I have never believed in extended warm up periods. I use synthetic fluids in my truck and as soon as the oil pressure is stable I drive it and it warms up much quicker.

I use synthetic fluids in my truck and as soon as the oil pressure is stable I drive it and it warms up much quicker.
define stable (just wait till you get to mass)

The 5w is a real helper.

It was 17 deg. outside this morning....let it idle for about 10 mins on high idle....hit 185 in about 10 miles. Its interesting to me that some trucks are taking so long to warm up. Use the high idle feature and see if it helps.

What is the high idle feature? I started my truck this a.m. with outside temps around 32* and it didn't idle any higher than normal. I figured it would raise the RPM's until warmup. I'll drive in the morning with similar temps and see what the tstat does. Mine always climbs to 205*. JJ :)

JJ check out the DIC settings in the owners manual.

I put the grille portion of the winter cover on mine and it does help quite a bit. The bumper portion of the cover looks like a real pain, so I probably won't ever install it. I drive about 21 miles to/from work. Yesterday it was about 30 degrees on the way home, but no problem with it getting too warm with the cover on.

masterp2, my truck doesn't have the steering wheel mounted controls mentioned in the owners manual. Evidently the DIC controls/provides a lot more information if you have the complete system.:o

Anyway, my concern was that at 32* my truck didn't bump the idle up at all. I didn't like the way the truck sounded when I first started it up. It took about 2 seconds for the glow plug indicator to go out, this is usually almost instantaneous. Once I started driving it ran up to its usual 205*. I'm curious about some of the guys running at 180-185*. My truck always runs at 205* while moving. If I sit at idle for a couple of minutes the temps will come down some, usually to about 190-195* in cool weather.

I'm curious if the guys with the cooler running LLY's are also experiencing bad diesel mpgs? I checked my around town mpg's the other day and they were 15. I consider this quite good considering it is a dually and I remote start this truck every time and allow 2-3 minutes warm-up before driving, even more time first thing in the a.m. I've always been told that engines run more efficiently at higher temps. :confused:

If the tstats aren't functioning correctly it may hurt engine efficiency by keeping the LLY too cold. JJ

JJ, I still think you can set hi idle.

Max Power would know.

BTW, JJ, many people report engine temp from the attitude. It appears to be 10-15 degrees behind of the gauge at operating temps, the gauge is not very good. I noticed it is very sensitive to stats opening and closing, so the gauge sensor is probably the one right on top of the stat, if so, poor design.

Know that 205 on the gauge is anywhere from 180-200 on the attitude.

I am certain the edge picks up data from a diff sensor.

JJ, do a search on this board - there are instructions for how to enable high idle without the DIC.

It's something like:
1) Turn key to ON. Engine OFF.
2) Hold gas pedal to floor.
3) Pump brake pedal 3 (or is it 5?) times within 5 seconds.

You should then see a message appear that says "HIGH IDLE ENABLED".

If it's below 32, the truck is cold, and the truck has been idling for more than 30 seconds, the idle will creep up to ~1200.

Or just sleep later JJ

Thanks mp2. I found the instructions in the Duramax Diesel pamphlet for the non-steering wheel mounted controls. Outside temps of 32*F or colder and the engine coolant below 150* F before it engages. I don't believe it was below 32* when I started the truck. If it is not engaging there is a way to manually engage and disengage. Thanks again. JJ :)

this A.M. it was 18* and it took mine 7 miles of backroads driving (50-60mph) to get hot (185*) The heater and defroster start to work when engine temp reaches around 170*. No winter cover.
Cruising at 60mph it will reach 205*F after the initial 5-7 mile warmup period. It then cools back down to 185*F at idle. I've been averaging 16.7-17.7 mpg around town-no highway miles to and from work but I do have a couple of stretches where I get up to 60mph for 2-3 miles at a time.

I run Rotella 5w-40 synthetic so oil pressure is usually 50-60 within 3 seconds of starting up.

MGMACK, ever thought a remote start system. I have one on my truck, it allows me to start the vehicle 5-10 minutes before I'm ready to leave. Truck is usually warm when I get in it, gets up to full operating temps quuicker. There's some good info on the site about them. JJ

I run Rotella 5w-40 synthetic so oil pressure is usually 50-60 within 3 seconds of starting up.That must be idle?? Mine is higher, on a 40 degree morning. What is it when warm??? I run the same oil and It doesn't get down below 60 on the road (over 1200 rpm) till the truck is warm.

JJ what remoter are you using? features?

I purchased one from Circuit City so that I could have nationwide service if needed. My previous truck had a remote start that left Mama JJ stranded up in Murpheesboro, Tennessee at 10pm at night. Not a pretty sight! :eek: That one was a Viper.

The CC system has a lot of features. I can set the truck to turn itself on/off at different time intervals throughout the night. Also can set the cab temperature and the truck will start itself, warm or cool to the pre-set temp, then shut itself off. Kill switches on hood and doors. Tailgate is wired as well. So far I'm pretty happy with it, though it has its moments when I'm around airports with radar interference. The remote is an FM transmitter so evidently it can get interrupted by a stronger signal. The system has a diesel engine setting and a gas engine setting. I had mine set for gas since the LLY's glow plugs heat so fast. No problems so far. I do need to have some adjustments made for the glass breaking sensor. It operates off changes in cabin pressure, so when I leave the windows cracked it gives some false reads. One thing I really like is the horn blows really obnoxiously versus a siren that everyone just blows off.

Those considering a remote start system should do a search on this site. There are several brands that appear to be of high quality. JJ :)

I'd like to get a remote start, for the really cold mornings. JJ thanks for the tip on CC.

mgmack, the CC system has settings for gas and diesel engines. The LLY glow plugs are so quick I use the gas settings. The diesel has about a 10 second delay, gas about 5, plenty of time for the LLY in most cases, though you may want to time it in extreme cold weather to ensure adequate delay before starting. I checked mine this morning at 42* and it took about 1 second for glow plug light to go out. JJ :)

mgmack, the CC system has settings for gas and diesel engines. The LLY glow plugs are so quick I use the gas settings. The diesel has about a 10 second delay, gas about 5, plenty of time for the LLY in most cases, though you may want to time it in extreme cold weather to ensure adequate delay before starting. I checked mine this morning at 42* and it took about 1 second for glow plug light to go out. JJ :)I noticed yesterday with outside temp at 22*F my glow plug light only illuminated for 2-3 seconds. So I think the gas setting with 5 seconds should be plenty of time. It rarely gets below the teens here in Fort Bragg.

I'm familiarizing myself with how long it takes the glow plugs at different temps. We're supposed to hit the low 20's this week, good time to check em at that temp. JJ :)

Time to look at citrus futures JJ?

BTW, yes the avatar has something to do with what you said.

7.8 degrees outside yesterday morning, I hit the remote starter from inside the house, the truck cranked up and ran for 12 minutes as programmed. I'm using a Valet remote starter (DEI brand), which utilizes the factory remote keyfob, and was installed by my Chevy dealer.

While the truck isn't really fully heated when I get in, it's well on its way. There is a built in feature to cycle the truck on for a 12 minute run every 3 hours. Just an FYI.

http://www.directed.com/security/valet/default.asp

Site has a feature to find and speak with installers. Shop around.

32* temp this morning, remote started, glow plug indicator took about 1.5 seconds to turn off, starter engaged about 2 seconds later. I'm waiting for some really cold temps to see if a significant delay in glow plugs is encountered.

Question: If the truck tried to start just before the light goes out could there be serious damage to the truck? JJ :)

I have noticed that using tow/haul during my first few miles of driving helps the engine to heat up quicker since it operates at higher RPM's and downshifts using the engine. FWIW. JJ