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Topic: Cold Start Question  (Read 692 times) previous topic - next topic

Cold Start Question

I have a cold start question. I think it was around 30 today when I 1st tried starting my 1996 U296 8.3 Cummings. I turned the block heater on for 3 hours before trying to fire it up. I turned the boost switch on, turned the key, and waited for the wait-to-start light to go off. It took way longer than normal, about a minute. It always starts right up. When I turned the key it tried, but within seconds stalled. I turned the key off after each try, waiting for the wait-to-start light to go off. Each time it took about a minute for the light to go off. It took about 4 attempts to get it started. When it did, it was rough for the first minute, then ran at a high rpm of 1500 (15000) normally it is around 5500 (550) for the first 3 or so minutes. Then it came down to 1000 (10000). I gently pushed and let off the gas pedal a few times and it dropped down to normal and I took off. Everything was good after that, all temps were normal.

Re: Cold Start Question

Reply #1 –
I turn my block heater on the night before, when it's that cold.

Re: Cold Start Question

Reply #2 –
It takes longer in the cold for the grid heater to get hot, that's why the wait light stays on longer.
If you run your generator you will get extra amps from the inverter charger. It you have a heat gun
or a hair drier heating up the intake manifold will help getting the engine started. Having the block
heater on longer also will help.

Re: Cold Start Question

Reply #3 –
30 F isn't that cold.  I suggest you check your engine block heater.  They can burn out.  With your hand, you should be able to feel some heat close to where the heater is after a couple hours.  Sometimes the block heater might be unplugged from the outlet due to the fear of it being switched on accidently by someone's foot. (BTDT)

I also suggest verifying that the grid heater is working.  I'm not a Cummins owner, but the grid is 12 volts and when the dash light (and the grid) goes off you should see the voltage bump up very slightly.  Maybe others in the know can chime in on this subject.

Maybe I'm reading it wrong, but it sounded like the engine would crank but then come to a stop? (with the key still turned in the crank position?)  That shouldn't happen with good batteries and and good cable connections and being plugged in overnight (thus fully charged batteries). 
The cold does a triple whammy for starting: 
- harder to turn engine due to oil thickening
- more cranking is needed to generate compression heat (the grid and block heaters helps this part a lot)
- batteries have less effective capacity. 
In warm weather a weak starting system will seem 100% fine because it's not being taxed much, but the cold will show it's true colors.
I would read this as a warning that something is not 100%

Re: Cold Start Question

Reply #4 –
Rotational speed is critical for starting a diesel engine. Sounds like your battery capacity has decreased, cold increases starting loads.
Coach wont start trouble shooting (Battery)

Re: Cold Start Question

Reply #6 –
Please note "Bobw" s  battery post charging Q and see reply 4.