I'm having issues with my truck starting up in the AM. Its about 15 degrees in the mornings here now, and when I crank it, it cranks very slowly and barely starts. Bat, reads 10ish and takes a few minutes to get up to over 14. Any ideas? Glow plugs????? I have no clue. JP

#1 how old are the batterys?
#2 any codes?
#3 how many miles, IE starter is going

have you tried plugging it in? also, changing over to a 5w-30 diesel oil will definatly help for the winter starts. i run the amsoil 5w-30HDD oil in my truck

I replaced batteries last month for the same problem. Ok now. I also run 0W40.

80K miles
New bats as of 50K miles
no codes

Dont have a block heater.

if you have an engine block heater you need to plug it up. the cord should be located under the air box between the block and the fender and have a 3 prog head on it. Works wonders in cold weather, went to crank mine in 25 degree weather and the wait to start light didnt even come on and it started great.

Well, like I said above, no block heater. I grew up in montana and we didnt plug in our trucks till it was well below zero. I cant see how 15 to 20 degrees is making it quite hard for my truck to start? ? ?

It should not be hard to start at 20 degrees. The batteries have 30,000 on them, I would have them tested (easiest place to start)

Is your glow plug light coming on, and for how long?

Take care
Mike

coldest i started mine was -30 out. and what was ambient air temp. it cranked over slow but still started.

I suspect one of your new batteries is going south.

Unless I am mistaken, all Duramax engines came with a block heater. I am not saying that plugging it in will solve the problem, just that your should have a heater. It sound to me like a bad battery. Mine did this when I only had one good battery.

i though they all did too????

Well, like I said above, no block heater. I grew up in montana and we didnt plug in our trucks till it was well below zero. I cant see how 15 to 20 degrees is making it quite hard for my truck to start? ? ?

My truck was just like yours last winter, i run 15w 40 diesel oil in mine all year round though. I plug mine in this winter and it starts to do the same about 10 F or below. I would say its normal. Just remember these are very cold blooded, they do take a little bit more work in the winter. Just keep it out of the cold breeze and you should be fine.

i though they all did too????

On the LB7, the block heater cord is located on the negitive battery terminal on the pasenger side, about a foot or two away from the battery. The LBZ and LLY, they were an option to get them. My gues they were able to get the motor to respond better in the cold.

My glow plug light comes on for about 10 seconds or so. Wondering what your bat read is before you crank in the am....? Mine is about 11 to 12. Then after runing for a minute or two its over 14. IS THIS NORMAL.

WHAT! All come with a block heater!!!!! NICE. I will go look. Sorry for my ignorance. But I still think its warm out. -30 is more like when you need to plug it in. LOL.

Check for the block heater cord to be zip tied up somewhere on the passenger side of the engine. Mine was a PITA to get at. I wish they would have thought about cord placement! Anyways, 14.5 after a few min. is normal. Though 10v before you crank sounds like a bad battery. Have each battery load tested. Make sure each is tested separately. If they are still hooked together it will throw the results off.

Your volt meter is reading that low when you start it due to the intake warmer and glow plugs or something like that, then when the warmer licks off you see the rise in the volt gauge, it takes anywhere from 15-40 seconds or so. The time is shortened the warmer the engine is, and the warmer will not come on at all when the engine is at operating temps.

I believe this was the question you were asking?