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Should I let my 3.0 warm up?

11K views 21 replies 12 participants last post by  Wiley75 
#1 ·
So I've had my '15 GC for 2 months now, and put on 6k miles already. I'm up in Wisconsin where the Winters are cold, and the summers are for road construction, so I'm used to letting my vehicles warm up at least to minimum temps before driving them, but am new to the whole diesel scene.

My question is this: Should I let my diesel warm up in the morning before driving it? I know with the EGR and DPF systems, idling for long periods of time is bad, but I also know that Diesels run off of compression and heat, which may incorrectly lead me to believe that I should let it warm up before driving it for the day, especially when my temps are regularly single digits. My routine is to turn on the remote start 3-8 minutes before I plan on driving it, and usually want the engine oil temp to be somewhere between 80-100F because anything lower and the turbo seems to have a little bit of trouble spooling up. Is this nonsense? Am I doing it completely wrong?!
 
#2 ·
Engines warm up best when you drive. I let my vehicles gas or diesel idle till the tach comes in around a grand. But i don't live in WI. Next time you fire it up see how long the tach takes to reach a grand. I like that number because the trans isn't slamming into drive or reverse, and I'm not glazing a clutch taking off.-Rockydee.
 
#6 ·
I've noticed that by putting my foot on the brake while in park, the engine will actually bring down the RPMs so that it can shift without risking any damage to the Trans/Clutch. Pretty neat technology

Get in the car, start it up, put on your belt, check your mirrors and then just drive off. Keep your right foot "under control" for the first few miles and you will be just fine :thumbsup:
I typically keep my right foot under control until my oil and water are at least 100, and usually won't step on it until I'm 170+ on the oil temp. Am I babying it too much?

Diesel fuel can gel up when it gets real cold.The injector pump on a diesel motor will have a return line to the fuel tank.The extra fuel not used by the motor is warmed up from the motor,returned too the fuel tank and this cycle will warm up your fuel and your diesel will run better when warmed up!:thumbsup:
You know, I thought that the fuel tank in the diesel came with a 12V heater to prevent gelling, but that may have just been my salesman talking out his ass. He also claimed that sport mode limited the gearbox to 6 gears, and that the diesel could tow over 10,000 pounds (after he asked me to convert tons to pounds for him)...
 
#3 ·
Start, wait 15 seconds or so then and drive away, it will heat up way faster. I just don't gun the car in it's first seconds of operation under ultra low temps...we usually see -15 to -20 these days...by the time I get to the highway ramps, the car has taken some heat...
 
#4 ·
Get in the car, start it up, put on your belt, check your mirrors and then just drive off. Keep your right foot "under control" for the first few miles and you will be just fine :thumbsup:
 
#5 ·
Diesel fuel can gel up when it gets real cold.The injector pump on a diesel motor will have a return line to the fuel tank.The extra fuel not used by the motor is warmed up from the motor,returned too the fuel tank and this cycle will warm up your fuel and your diesel will run better when warmed up!:thumbsup:
 
#7 ·
my father is a retired master mechanic and he has always said do not let a vehicle sit and idle for more than a minute at most. Condensation builds and obviously water is not good.
My routine is as stated previously - start - belt up shift to reverse and because the diesel has so much low end I drive way and you should never have to exceed 2k rpm until you have driven a mile or 2. This allows ALL components to warm evenly- trans, diffs, transfer case etc. Imagine a warm engine - then you take off and 3.5k rpm will full power of the rest of the components.
make sense to me but what do I know :)
 
#8 ·
Nah! Not babying it too much at all. Like yourself, I like to see my temps rising before "getting into it". We also tow a trailer, so I like to see temps near normal iin our JGC before using more throttle. Of course, if I NEED to, that's another matter entirely :D.

Same with my motorcycle, I like to see at least 3 bars on my RID display before exercising my wrist further ;)!

The Jeep has synthetic engine oil as standard, which is great, but I also use synthetic lubricants in all our vehicles. Even down to our travel trailer wheel bearings and the gearbox and final drive of my motorcycle :thumbsup:.
 
#9 ·
Yes just start and go, but take it easy until she warms up. Once warmed up, accelerate as hard as you want.

I do the same on my motorcycle too, an R1200RT. Looks like we have the same (good) taste in vehicles.
 
#13 ·
I let mine warm up, 5 to 10 minutes from cold start. just hit the remote, many reasons behind this, both engine and transmission related. I am an engineer for an OE Diesel engine mfg.


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Hey C175,
Could you please elaborate on the "many reasons" that are "both engine and transmission related?" I'd like to know why the 3.0 VM engine and ZF 8 speed transmission need 5 or 10 minutes, from your perspective as an OE Diesel Engineer

Wiley75
 
#11 ·
Here's a good explanation on letting the engine idle. See the video.

Lot of old school folk say don't let a diesel idle, old diesels had flat tappet cams and P&B mechanical injectors that didn't control fuel at all. Dump the engine full of fuel and wash the rings. Todays engines are high fuel pressure, computer controlled injectors and overhead camshafts, idling for minutes at a time is no problem at all, specially since you can take your engine to full load and clear out the carbon. One thing to keep in mind a diesel engine makes 1 gallon of water for every gallon of fuel burned. Creates what they call Soup.. wet stacking.. slobbering you see from a diesel exhaust.

https://www.youtube.com/watch?v=91Rv2jxDkhk
 
#12 ·
Idle a few minutes before take off and minimum load until water temps get to normal conditions, just remember both the oil and atf heat at a much slower rate than the water. Engines and trans operating at less than optimum temps will experience more wear. If you only keep you cars a few years this would not matter though
 
#14 ·
When the engine is warming up the transmission is coming up to temperature. With a cold transmission you can have slippage, seals leak etc. Engine wise I'd rather see the engine warm up no load to 100*F before driving, 160*F before full load. The pistons swell up with heat as do the rings to fit the bores. Running a cold engine the pistons are slapping around and getting additional blowby with the ring gaps wide open, without any warm up.


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#16 ·
It takes forever for this engine/transmission to reach operating temp. I usually let it warm for 2 min in the driveway and go, per the manual. I won't see 160+ until 10-15 min, and operating temp of slightly over 200 around 20 min, and that's while driving. The transmission however takes an hour. It usually settles in the 190s. My daily commute is 30 min so it's never getting there. The engine will warm the transmission, but I doubt to any reasonable temp for a while, and then you're redirected to the threads about excessive idling.
 
#18 ·
I should have clarified that my emphasis was on the transmission taking forever. Just took a 43 min trip engine start to stop, with two idle breaks while I ran in two stores. Took readings every min but here's the breakdown:

Before starting
Outside temp 40
Garage temp 43
Oil 42
Trans 44

Min/oil/trans
Start+
1/48/48
2/59/51
3/69/55
Left garage after 3 min idle
5/102/68
10/161/86
15/192/102
idle break min 15-19
19/194/107
20/195/109
21/197/113
Idle 21-25
25/195/118
30/201/136
35/201/149
40/199/159
Parked
41/197/161
42/197/163
43/197/163

Noticing the idle times the trans temp still rises meaning its being warmed by the engine. Still had 30 or so degrees to go after 43 min.
 
#20 · (Edited)
Dude I can tell you the only reason you don't want to idle for a long time is carbon deposit buildup, but in actuality any operation outside of recommended temperature will cause more wear, and this wear is proportional to the amount of load the engine experiences. Again like I said before if you absolutely want to make the engine itself last the absolute longest, ie cams, valves, rings, bearing, wall roundness, etc you should operate your car at standard operating temp only and use fuel injector cleaner to combat any carbon buildup. Can you idle for 3 minutes and go? Yes. How much more wear will this cause vs idling till operating temp? Very low. Will you notice in a leak down test after 100k? Yes. Will it still be in within specs? Yes. It's your car only you know how long you want to keep it for and if you engine is still 100% and the rest of your car is falling apart.....

I idle for 3-5 minutes before driving, because I don't plan to keep the truck forever and also because I'm cheap and don't want to burn fuel. As long as you don't load the engine much before fully warmed up you will be fine, that is the worst thing you can do.


Hope this helps.
 
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