Cold Weather Operation

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Cold Weather Operation
and the GM Diesels
Updated for 2012: Operating a diesel engine during the cold winter months demands that all diesel fuel and electrical systems operate normally. Included here is list of precautionary measures and cold weather strategies that will help your diesel pickup operate reliably throughout the coming winter. If you're new to the GM diesel, the information found here should help to answer your questions as well as reduce any anxiety you might have about cold weather operation. It's really easier than you think.

USDP's 2012 Dyno Day
USDP's sixth annual Dyno Day was held this past June 2, 2012 here in Missoula Montana, and the crowd just keeps getting bigger each year. From morning till late afternoon, 3 dozen of the Big Three's diesel pickups rolled across the Mustang dyno rollers and kept everyone entertained.

[DennisG01]

Concerning the fuel cap... I had always thought that a fuel cap kept a constant vacuum on the fuel in the tank. I did not realize that, instead, it was designed to keep a slight pressure OR vacuum on the fuel. Thanks!

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Concerning the fuel cap... I had always thought that a fuel cap kept a constant vacuum on the fuel in the tank. I did not realize that, instead, it was designed to keep a slight pressure OR vacuum on the fuel. Thanks!

That's right! Every fall, we get a number of reports of engine running problems that can sometimes be attributed to a faulty vent in the fuel tank cap. When summer temperatures transition to fall there can be large temperature swings between the daytime highs and the overnight lows. This large swing causes the fuel in the tank to expand/contract more than at other times of the year, which can produce more pressure or vacuum in the fuel tank. The vented cap is supposed to deal with it.

Combine a bad cap vent with a weak fuel filter seal or problem with a fuel line, and a fuel or air leak can result. Caps are cheap, but be sure if you do replace it to buy a genuine "diesel" fuel cap (preferably one from GM). A gas cap isn't vented at all or isn't vented the same (a gas engine powered vehicle uses a fuel vapor recycling system). Jim

[EdHale]

Jim,

In your Cold Weather Operation update that you posted a couple of weeks ago, you state that "2001 and newer Duramax equipped trucks came with a grill cover tucked away under the rear seat". Was this cover included with all Duramax trucks or only ones that were originally shipped to norther dealers?

I'm asking because I have a the 2006 LBZ in my signature and if there is a cover under my rear seat I need another clue to find it. Now living in Alabama I certainly don't need it, but if it is there I would like to know it. You never know, since I'm retired I might go visit Mark up in the north country some day.

Thanks Jim.

[Mark Rinker]

Ed - that would be fun for sure, but you better hurry because we are headed for Seattle next spring...

If the cover isn't there, it isn't there - they aren't hidden, just sitting in a plastic bag under the seat.

They always seem to be missing when I buy trucks - I have purchased new on Ebay, from people in TDP that live in the south regions, and (lastly in desperation) over the counter at a GM dealer.

The BEST reason to use these covers (beyond the obvious quicker warm-ups, better fuel economy, and moderated engine operating temps) ???

They keep all the grit and sand and salt that covers the roads in these winter conditions OUT OF YOUR ENGINE BAY, and OUT OF YOUR COOLER STACK.

Bugs eventually get wet from rain and break down with heat. It they get bad enough, you can easily use compressed air and water to flush them backwards out of your coolers.

Grit, sand, and salt? That stuff does a lot more damage and is harder to remove from the fine slits of the coolers, in my observations.

I use my covers anytime weather drops below 10F.

[EdHale]

Thanks Mark. My 2006 didn't have one, or the dealer "borrowed" it before I came along.

10F? I can't tell you the last time it was that cold here. This past winter I don't recall it ever getting below 20F? Two years ago I remember a couple of nights in the 13F range. Now the local "fuzzy worm" weather forecasters down this way are predicting a much colder winter. We shall see. I do remember our last snow (other than just a few flakes) was in 1993.

I just plug my truck in when it is going to get that cold.

[AKMark]

My 05 has a Block heater, a small automated battery tender (only works when the batteries need a few amps, not full time) an oil pan heater, a transmission pan heater, and at -50 or worse she fires right up.

The 99 has the same except that instead of the battery tender, it has two heating pads underneath it's Optima's to keep them warm and operating at max amperage. It's a toss up which system works best, because as long as either truck is given 1-2 hours of plug in time, they'll fire right up at -50.

The 6.2 has 2 block heaters, battery warmers, and the oil pan pad. It's a stick so I don't warm the transmission on it, however, I've found I have to sometimes leave it in neutral when it's cold. At -50 the oil is so thick, if it's not in neutral, I have to put the T-case in neutral so I can let the clutch out. Which can also be a chore. I've had days where I had to drive around the block (luckily it's only got a few houses on it and little traffic) in first gear to get the fluid warm enough to move the shift lever. I always leave it in a gear I can use before shutdown now. (I usually back into my parking spots, and leave it in first, just in case)

All three of my trucks have cardboard blocking the radiator, and the 6.2 has dual electric fans that are manually triggered. In the winter, the only time I use the fans is on big hill climbs while offroading in low gear. Once you're moving, even with the radiator blocked off, it doesn't need the fans to maintain 195.

[Subzilla]

Wow! Extreme stuff! I can't imagine 80 degrees below freezing. It just doesn't register to me.

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In the "for what it's worth" category, GM sent several Duramax prototypes to Fairbanks in late 1999 to be tested during the extreme cold of an AK winter.

The factory-included "winter front", cold warmup/glow system programming and other mods resulted from their time spent there. At the time, the engineers I spoke with said getting the engine to warm up was a challenge because so much of the design and development of the engine had gone into ensuring it ran cool while towing heavy in the summertime desert heat. Jim

[93GMCSierra]

Wow! Extreme stuff! I can't imagine 80 degrees below freezing. It just doesn't register to me.

I used to live in North Dakota, and while -50 is extreme late dec to early feb temps were generally below -30 with times of colder.