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Well...

I can't say what the lower cold limit for starting is, but here's what I've observed with mine:

At 50°F+, the starter "grunts" one or two times (and I assume that each "grunt" is the slowdown that happens when a piston comes up on compression..) before it's running. So, 1/2 to 1 turn of the crank and running.

The other morning, when it was 28°F (coldest it's been since I got it this summer, and y'all up north can quit laughing now..), I went out to start it just to see how it'd do. Didn't plug in the block heater, no grids, nada. I counted about 5 "grunts", so 2.5 turns of the crank, and we were running. So, 28°F doesn't appear to be a problem.

I'll share this trick, too:

If you're starting in the cold, keep cranking for about 10-15 seconds, especially if the thing is just barely cranking over. If you don't start on the first attempt, don't panic. Wait about 2-3 minutes, then try again. I'll bet it cranks MUCH faster on the second go, IF YOU WAIT..

What you're doing is heating the batteries (and pre-heating the engine a bit, as well as putting a little more lube to the bearings..) on the first try. Takes a couple of minutes for it to have a positive effect on battery output. If you don't wait and just try again after only 30-60 seconds, or just keep grinding the thing, it's not going to help.

Of course, optimum is to have a setup that provides enough oomph to do the job at whatever temperatures you operate in.
 

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crewcab59 and i have started and I drove a breadvan back from North Carolina when it was in the 20s. Started just fine
 

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The 4b have block heaters ,not grid heaters unless they have been installed from the 6b.The 2 Vans started just fine @ 20 * .

My 6b will start @ 15 * under that I have to use the grid heaters.

Scott
 

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Started mine this past winter @ 18*F, no heaters, forgot to plug in.
Carl
 

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The first Dodges that came with the non-intercooled Cummins engines had a thermo switch that did not turn on the grid heaters until the temperature was less than 20° F or -6° C. Of course these engines were also equipped with the electric jacket water heater which is a diesel engines best wintertime friend. If you have a situation where it is impossible to plug the heater in then you should try to always have a battery and starter in good condition, a set of jumper cables, and clean oil. A diesel rated synthetic or synthetic blend oil will also help considerably.
 

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I'll be traveling to North Dakota for Christmas, so I installed both the block heater and a Grid heater on mine. I plan to use both devices if temps will be below 0*F like they often are.
 

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Had -5C here so far. I get one "re-er" out of the starter and it's running. 1/2 crank and it's running, battery is the original 525CCA Mopar battery that came with the truck in 2000 (half life reading on load test). Not on the block heater, no grid heater either.

Apparantly there's a 'flame tube' heater for the 4bt. Takes fuel out of the return line and burns it in the intake manifold to heat it up. I want one just because it sounds cool.

Fire!!!
-Scotty
 

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I just pulled my engine out of an wonder bread van. It had no grid, no block heater and a group 24 battery. It started quicker than a gasoline engine on a couple 20* mornings.
 

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Apparently there's a 'flame tube' heater for the 4bt. Takes fuel out of the return line and burns it in the intake manifold to heat it up.
Yanmar Tractors use that, it is called "thermostart".
The flame is right inside the intake - - - NEVER use ether!!!
 

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The coldest morning I started mine was about -10*F, you could tell that was about it. That was with no block heater or starting aid, and two group 24 searies batteries. This winter Im hooking up an intake heater for good measure.
 

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Discussion Starter #13
Had -5C here so far. I get one "re-er" out of the starter and it's running. 1/2 crank and it's running, battery is the original 525CCA Mopar battery that came with the truck in 2000 (half life reading on load test). Not on the block heater, no grid heater either.

Apparantly there's a 'flame tube' heater for the 4bt. Takes fuel out of the return line and burns it in the intake manifold to heat it up. I want one just because it sounds cool.

Fire!!!
-Scotty
I like the idea of this, can you update us when you get one?

Jeepcummins -10f, I think thats -26C , thats cold for non assisted starting, don't think I have anything to worry about here. Can anyone beat this?

Gaza
 

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I'm hoping that mine is as easy to start with the sub zero temps we get here.:(
 

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I'm hoping that mine is as easy to start with the sub zero temps we get here.:(
Install a block heater. It took me about 10 minutes total once I spun the oil filter off. ;)
 

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Mine has started reliably in temps below -15F with the wind chill something like -40F.
 

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Install a block heater. It took me about 10 minutes total once I spun the oil filter off. ;)
My 94 bread van came from Chicago so it came with one. I was thinking of adding a grid heater from a 6Bt, think I'll need it?
 

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I was thinking of adding a grid heater from a 6Bt, think I'll need it?
It depends on your needs and actual climate.

The 6BT grid install was kind of a pain in the ass, a lot of the injector line support brackets can't be reused unless you do a little cuttin' and weldin'.

Need pics?
 

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The 4b have block heaters ,not grid heaters unless they have been installed from the 6b.The 2 Vans started just fine @ 20 * .

My 6b will start @ 15 * under that I have to use the grid heaters.

Scott
Two of the vans I have dont have grid heaters but they do have the square intake to install grid heater, its Cummins part, not chopped 6bt intake. But havent looked at part #
 

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I can't speak for the 4bt, but I haven't had any real problems starting my '96 6b on -30 f. mornings. I use the block heater when its below zero, and cycle the grid heater twice before cranking it. Because it works so well, I'm using a block heater and modified grid heater on my wife's Durango 4bt swap.

For those who have done it, what exactly is supposed to need welding on the modified 6b intake plate/grid heater? I cut mine down to a cast-in rib and it looks like it will seal just fine without doing anything else. I might use JB-weld to widen the rib a bit to ensure proper sealing, but I don't think its really necessary. Also, what else is required to have the automatic timer for the Dodge grid heater (temp. sensitive)? I have the heater and relays, but don't have a wiring schematic. I may just wire it up to a push button and have her hold it on for several seconds. I'll also have it wired in to the remote starter I'll be installing for her (with accessory solenoid wired in for high idle during warmup)

Jim
 
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