Diesels and Block Heaters

Johnny Quest

Web Wheeler
Location
West Jordan
In case you haven't noticed, its getting a bit chilly, especially in the morning, and my Duramax didn't want to start this today. I did not have the block heater plugged in, but after struggling with it for a while, I plugged in the block heater, and what do you know, it fired right up. I was under the impression that diesels didn't need to be plugged in until sub-zero temps, but apparently I was wrong,

So whats the rule of thumb when it comes to block heater use? Below freezing? Below 20*?
 
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Spork

Tin Foil Hat Equipped
Depends on the vehicle, my VW doesn't have a block heater and always starts. My folks had an old 80's rabbit and it had to be plugged in anytime it got below 50. If it's struggling to start I'd plug it in. If you have a timer you could set it to kick on an hour before you leave if you don't want it running all night.
 

Houndoc

Registered User
Location
Grantsville
I have never had one on any of mine. No problems with cold weather starts.

I was most surprised a number of years ago when I traveled in the winter onto the tundra in Northern Manitoba and the old snowcoach had been converted into diesel. 100 miles from nearest town, temps-30 or less.
 

boogie_4wheel

Active Member
Check/replace your glow plugs and maybe the glow plug relay. It isn't cold enough to keep one from firing if a majority of the glow plugs are functioning.
We had a 90's 7.3 PSD that was horrible in the cold until all the glow plugs were replaced. My Cummins (grid heater in the intake) has not been a problem at -25, but it took a few seconds for all 6 to contribute.
As for the block heater, stick it on a timer to come on about 3hrs before you plan on driving. If you daily the Duramax, consider a winter cover for the front to aid in it getting to operating temperature. I'm a cheapskate so I use a foil windshield sun shade in front of the intercooler. It gives me an easy 20+ degree jump on intake temperatures.
 

Mouse

Trying to wheel
Supporting Member
Location
West Haven, UT
I only use the block heater if it's in the 20's or below. I also make sure to let the glow plugs run a bit longer
 

Gary T

Registered User
Location
Draper, Utah
I had an 03 Duramax, and occasionally it didn’t like to start on cold morning. I would do the prestart cycle twice sometimes to get the glow plugs nice and warm. Never did anything else to it.
My 17 Duramax has no problem with the cold, but I don’t dd it.
 

xj_nate

Doctor, economist, polical expert, poser
Location
UT
I haven't had an issue with starting but I do have the block heater just in case. I hope I never need it. If I were you I'd run an extension cord to it and rock a smart outlet of some sort to turn it on with your phone a couple hours before you need to start it. Seems like a good solution.

I put the cold weather cover on my '20 Ram and it's amazing how much of a difference it makes when it's running.
 

Rot Box

Diesel and Dust
Location
Smithfield Utah
Yep totally depends on vehicle. There are some things to keep in mind though.

Battery condition plays into it a lot. The highest cca batteries that will fit make all the difference.

I run 5w-40 year around but it really helps in the cold months. You don’t have to worry about heui but the 5w would help you crank over faster especially if it sits for a length of time.

If you do find yourself needing glowplugs and relays please run oem for your truck. Aftermarket parts store glowplugs suck so bad it’s not even funny.
 

J Kimmel

Registered User
Glow plugs and batteries.
My 6.0 starts anytime any temperature. My old 7.3 would start at -35 and so would my Duramax. I had a friend with a 7.3 that refused to start at 40 degrees.
If I plug mine in it’s like starting it on a 60 degree morning and if I don’t it’s a little angry but it fires all the same but my batteries are reasonably new and glow plugs all work.
 

Rot Box

Diesel and Dust
Location
Smithfield Utah
Also if you do go with a timer for the block heater be sure to get a heavy duty one. Most block heaters are 1000-1500 watts so the ol’ timer will need to handle that.
 

glockman

I hate Jeeps
Location
Pleasant Grove
I am daily driving my 6.0 recently. I have it plugged in every night. This morning it was 16 degrees and the coolant in the engine was 98 when it cranked for the first time. Warm air by the time I hit the end of the block is worth the $0.50 in electricity. Also, if you leave the heater control on defrost, the block heater defrosts the window pretty well.
In the Fords, the glow plug light only stays lit for about 20 seconds, but the glow plugs stay hot for about 20 more seconds. Cycling them twice has always resolved any starting issues I've had even in sub zero temps without the block heater.
 

skippy

Pretend Fabricator
Location
Tooele
I have owned cummins trucks for the last 15 years and I have never had an issue with cold starts, They also sit for a month at a time. I plug in my truck if its cold enough to want the heater though. Its just so much easier on your batteries, starter ETC. Not to mention its way easier for the engine to get oil pressure to the top end when its not the consistency of molasses. Also when you get in your truck and its already blowing hot air is a nice bonus.

With that being said is truck is parked inside 100% of the time.
 

1969honda

Premium Member
Supporting Member
Location
Cache
I'm a big fan of the block heater for exactly what @glockman and @skippy mention. It saves the batteries and starters a lot of work as well as ensuring good oil flow thru the entire engine and high pressure oil circuits. That being said, I hate 6.0L Powerstrokes with a passion and how hard they are on batteries, injectors, etc... but man they sure pay the bills and the check cashes every time! 7.3s IDI or Powerstrokes are cold blooded beasts, but dead reliable; almost as much as a 5.9 cummins. I don't have a lot of hands on experience with the Duramax engines, but the old GM 6.2/6.5 in the HMMWVs and CUCVs are another cold blooded, hard starting bastard. The CUCVs seemed to be harder on the glow plug ballast resistors and glow plugs on average.


Side note however, if you converted the CUCV over to a scavenged Case M400 skid steer intake grid heater,/polaris SxS starter relay/ manual toggle switch setup in between the air filter housing and j-code intake manifold they started the first time, everytime in the Afghanistan winters! 😇
 

Gravy

Ant Anstead of Dirtbikes
Even though it starts really well in winter (oweing to it's Belarusian manufacturing), I still plug in my tractor the night before I want to use it- 16 quarts of oil takes a long time to warm up. I figure oil pressure at start up is worth the electricity.
 

Rot Box

Diesel and Dust
Location
Smithfield Utah
Story time: I remember years ago my friend had Dodge/Cummins and when we went to leave work it was so cold the truck started fine but it pumped all the oil (15w-40) to the head and ran the sump dry 😳. No oil pressure and all the alarms were going off—not good.

I’d say plug in when you can.
 

ID Bronco

Registered User
Location
Idaho Falls, ID
I plug my duramax in every night when it's below freezing. It helps a lot. It will start without it but sounds much smoother when it's been plugged in. I actually replaced the heater last weekend, and the old one had burn't through on one side. It was good for 18 years though.
 

RockChucker

Well-Known Member
Location
Highland
I plug my duramax in every night when it's below freezing. It helps a lot. It will start without it but sounds much smoother when it's been plugged in. I actually replaced the heater last weekend, and the old one had burn't through on one side. It was good for 18 years though.
I’ve noticed that about mine too. My logical but probably wrong conclusion is that the oil is thinner at the block heated temp and flows better. I’ve also thought that maybe it is a valve lash thing.
 
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