How long to get motor hot?

Hi all,
Just a quick question on how long it takes to get your cummins warm, seems like mine takes forever, Leaving for home on my 30 mile commute last night it was about 40 F out and let it idle and warm for about 5 minutes, drive is done at 40mph on cruise control. Temp just slowly came up, after the first five minutes it was giving me somewhat warm heat out the vents but not full temp. But took about 20 miles to finally get just a hair under operating temp. Is this normal or time to look if the thermostat is stuck? Im sure Id get better mileage if the motor was at operating temp sooner

That sounds about right. It's getting up to full operating temperature, right? Just make sure. Hit the water neck on the intake or some good spot with like a temp gun and see what you get. Some vehicles have multiple temp sensors, one for the gauge, another for the ECM. The gauge temp can look good, but the actual engine temp could be lower. I'm not sure what RAM uses.

I don't have a 5.9, but have diesel experience in other (past) vehicles. There's a lot of additional mass in a diesel engine due to needs of higher compression/vibration, etc. Secondly, diesel's are more efficient (less waste heat). Consequently it's going to take the engine longer to warm up and since the HVAC heat is essentially engine coolant, it's going to take longer to throw meaningful heat. In addition, depending on how the heater core is sized, some diesel vehicles' heaters don't run as hot because diesel engines in general don't run as warm. Diesels are terrible for short commuting trips, but great for long ones! Or if yer in your truck all day for work, etc. Ok, you probably knew all that, but just throwing it out there.

I drove a Jetta Diesel for years. On average winter days around 20 to 25* F it used to take a solid 10-12 minutes of highway time (55-60 mph) until the engine would get warm enough to 'start' throwing some heat, and 17-20 minutes where it was throwing real heat. 5 minutes later I was at work just when it was 'starting' to get warm! That sucks when yer wearing steel toes! On really cold days where it would get down to -10 F or lower, I would put a small electric foot heater in the pass footwell plugged into an extension cord (by the garage) and turn it on for 10-15 minutes before heading out. Made a huge difference. On Jetta's they put seat heaters in every diesel for this reason. You put it on #5 setting and it would cook yer a$$! I didn't usually let it warm up for more than a minute or two. Don't really need to ..that stuff has been engineered out. Just a waste of fuel. Many diesel's actually cool down when sitting idling so it doesn't make sense to just let it idle for a long time. I'm sure all the diesel guys are going to flame in now. In my case I would make a lot of trips an hour or so, sometimes the whole afternoon driving ...in which case the heat situation wasn't always a big deal. On the plus side, if you come back to the vehicle in 15-20 minutes or so, it'll still retain some heat and you 'get' heat where you wouldn't in a gas engine. If someone was a 20 mile a day commuter in the N. states, I'd say drive a car with a 4-banger that heats up quick, save the diesel for camping trips.

Keeping it in a heated garage helps but the diesel fumes in a house garage become overpowering especially when the wind blows the wrong way and fills the whole garage with soot! Secondly, if you live in an area where salt is used, storing the vehicle in a warm environment increases the oxidation process and accelerates corrosion (a lot!). Some guys block the radiator and that may be something to look into when it gets really cold and there are different vinyl covers for that which you can open/close just like semi-drivers use.

I love the heat my 5.7 produces..

Ok, sounds normal then, just seems odd to me being used to my old jeep with the 4.0 I6 that thing gets hot in 5-10 minutes no matter what. Dad just bought a 17 with the 5.7, seems like a nice truck and motor. Has me driving the diesel to keep her on the road so when we need it for work its good to go

ej132 said:

Ok, sounds normal then, just seems odd to me being used to my old jeep with the 4.0 I6 that thing gets hot in 5-10 minutes no matter what. Dad just bought a 17 with the 5.7, seems like a nice truck and motor. Has me driving the diesel to keep her on the road so when we need it for work its good to go

Click to expand...

Yeah man, it's totally normal. If you have an outlet near by you can plug in the block heater instead of starting and letting it idle. I have mine hooked to a timer that kicks on 2 hours before I leave for work. I found that to work much better.

Greg
2012 | RAM 2500 | CCSB | Custom tuned by Double R Diesel
2016 | Heartland Pioneer | DS310

Power247 said:

Yeah man, it's totally normal. If you have an outlet near by you can plug in the block heater instead of starting and letting it idle. I have mine hooked to a timer that kicks on 2 hours before I leave for work. I found that to work much better.

Greg
2012 | RAM 2500 | CCSB | Custom tuned by Double R Diesel
2016 | Heartland Pioneer | DS310

Click to expand...

For sure, once it starts getting under 20 F when Im starting I start doing a timer and plugging for an hour or two before