M939 Winter Storage

[sandcobra164]

I thought I'd bounce some ideas off some smart guy's heads. In the past, I'd put the deuce to bed this time of year and I did the same thing with the 5 ton as well for the last 2 years. The deuce always started easy and of course the 250 in the 5 ton does not. I started the 5 ton up this afternoon at 41 degrees after sitting for who knows how long. I hooked the jumper cables from the CUCV just to be sure. I let the 5 ton run for 15 minutes to warm up and circulate the oil. I then put it at a 1,600 fast idle with the hand throttle and let it run for an hour at that speed.

Now to the question, would it be better to just let the engine wait out the cold weather or is it better to run it weekly at a high idle? I know letting a diesel run at normal idle (600 rpm) is bad. Tonight, I finally heard the shutterstat engage the fan and the truck finally hit 200 degrees on the gauge. It's never gotten that hot before running down the road but that's got to be better than letting it sit still.

 

[98G]

I mentioned this in your cucv idling thread. I failed to convince you there.

https://en.m.wikipedia.org/wiki/Wet_stacking

Note that wet stacking is NOT rpm dependant. It is load dependant. Idling, even at 190-200* and 1600rpm with no load is more harmful than just letting it sit.

My opinion - take it for a drive every once in a while, uphill and WOT at 2000rpm. In the meantime let it sit.

 

[sandcobra164]

98G,
This is where I want you to take me to school. I agree that running a diesel engine hard is best. I would like to know why running one at a high idle with no load vs letting it sit is a better idea. My observation in regards to the cucv idling low while burning all of the old fuel out was that he did just fine. I filled him up with 10 gallons of fresh diesel and he did just fine on the way home as well. My better half drove him in the Leesburg Christmas Parade and still good to go. I know the NHC-250 and the 6.2 are very different engines.

 

[simp5782]

From an article i have read:

The genesis, I think, is from seeing unoccupied long-haul trucks with their engines running, and the practice does have some basis in fact. Diesels do burn very little fuel at idle because unlike gasoline engines, their throttles do not restrict the amount of air they ingest. As for truckers, the practice seems to have stemmed from the need to keep diesel fuel from getting too cold in winter and gelling. In any case, letting your diesel idle for anything more than a short duration is a bad idea because while the engine will use little fuel, what fuel it does burn will not combust completely because the operating temperature is too low. Unlike gasoline engines, diesels need to be under load to reach optimum operating temperature—if they’re not, unburned fuel can cause needless pollution and even can dilute the lubricating oil, increasing wear. Plus, every time a piston travels up and down a cylinder, the rings and cylinder walls wear just a little bit. The best rule is, if you’re*not underway, shut it down.

On another note. When i am on the road i never shut mine off when its below 25.

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[red]

Raising the idle rpm doesn't really help with wet stacking, all it's really doing is increasing the wear on the cylinders and using a little more fuel. That's just diesel engines in general.

Put a load on it, or let it sit. It's only a couple months, worst case scenario just have to reprime the fuel system in the spring.

 

[98G]

I would like to know why running one at a high idle with no load vs letting it sit is a better idea. .

Let's examine what happens in each case -

Sitting unused : seals dry, lubricant steadily drains into the crankcase, batteries trickle down.

Idling without a load, even at high rpm : the heavier portion of diesel fuel is left unburned and condenses on the cylinder walls, and on all exhaust components from the exhaust valve to the exit. Frequently, condensed fuel serves to dilute the lubricating oil and increases crankcase volume. Lubricant is contaminated with acidic volatiles. Cylinder walls can become scored.

This is all very gradual. It's nothing you'll notice after a few hours of doing it, and running the truck hard in the spring will likely reverse much of it by burning off the deposits.

But I am firmly of the opinion that periodic maintenance idling does more harm than good.

 

[98G]

I've seen trucks started after 15 years of sitting, with no ill effects.

I've seen a diesel engine nearly ruined by monthly maintenance idling for an hour per month. It poured black smoke for hours after being started, and was unable to run at capacity. Over a period of hours it was gradually able to run close to rated capacity, and the black smoke went away as the deposits burned off. (Granted, this was a large generator powered by a large Cummins, not a truck. Generators ate generally much more susceptible to wet stack than trucks are)

 

[98G]

Delete

 

[wheelspinner]

My experience is they are like bears. Feed them well ( good fuel additive to prevent algae etc) then let em sleep. Just put continuous charge to the batteries so the alternator isn't over taxed at restarting. They will be plenty happy. And that is from some pretty old northern winters.

 

[clinto]

I understand why many collectors of special interest vehicles (be they a '65 Mustang or a military vehicle) "put them to bed" in the winter.

In places up North, where winters are more severe, there is more chance of traffic accidents and corrosion is an issue, both in terms of anti-snow and ice agents used on the roads. No one wants to drive their antique car or truck through that stuff and risk corrosion.

The other issue is the large amounts of snowfall-no one wants 3' of snow sitting on their canvas top.

But here in the deep South, with our mild winters, I don't really see a need to put stuff to bed for the season. The coldest weather we'll have will maybe be some nights where it goes down to the teens and a few days here and there that are sub freezing.

I think any vehicle should be able to be used year 'round here. Drive the thing once a month. Take your kids somewhere and buy them a cup of hot chocolate. This eliminates the debate over wet stacking and such. It keeps all the seals nice and wet. Helps keep tires from flat spotting.

I think this also helps keep the truck "mission ready"-with the predicted snow this weekend, I didn't even have to do anything to my M35A2C because it gets driven a couple times a month. All I had to do was give it a once over and check fluids, fill it up with diesel, etc.

All vehicles, but especially older ones share one important tribute: they hate to sit. And this is a real problem with antiques and classics. I have lots of customers who own $100K vehicles, that are magnificent restorations, where every single component was replaced or rebuilt. And the owners let them sit for 3, 4, 5 or 6 months at a time. And these vehicles, which are theoretically brand new, constantly have leaks, carburetors that clog up and just various little things like this.

I liken this to your lawnmower: You mow with it all summer without issue but then it sits from October to say April and in April it needs all this work to bring it back to life. Cars and trucks are the same.

So I say drive your 5 ton. I know the 250 is cold sensitive, so keep a battery tender(s) on it with an outdoor extension cord and install a block heater for super cold nights when you might want to use it the next morning.

 

[Karl kostman]

I used to be in my younger days a bib believer in starting trucks at least twice over the winter, well it was a pain in the butt every time to get them going because they are in a unheated warehouse so it was about 1/2 a day per truck to then lit it sit at high idle for an hour STILL knowing that its never going to get warm enough to benefit anything. I researched the subject a lot and came to the final conclusion that when year end comes treat the fuel, keep the batts charged and make sure the coolant mix is good! And when Spring comes and the weather gets a little warmer every truck fires up like I had it started yesterday, although the Unimog certainly SMOKES like nothing I have ever seen before on its first start of the year!
KK

 

[simp5782]

You can also add a bypass oil system that will burn off any fuel and water that may get into the oil system while running at idle. It runs the oil across a heated diffuser plate at 6gph. Plus it puts additives back into the oil that pass thru the less than 1 micron filter. It helps on excess idle.

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[USAFSS-ColdWarrior]

A good lively, almost livid discussion here. We're all entertained when simple information becomes inflammatory.

Just remember that pickling MV's over the winter suspends operational readiness.... if that's critical to your operational scenarios.

 

[rosco]

I don't bother to start my diesel equipment, unless I need it. Of course everything I have has a good pre-start heating system on the engine. If I do run them, even when idleing them, they are covered so that they are at operating temperatures, regardless of the extremes temps. They may not be shut down, simply because they must keep the operator warm. We are blessed with straight diesel here, because the additives that cause fits (alge) elsewhere, freeze here. Winter fuel, otherwise is straight #1. I had 400 gallons of fuel capacity on the truck in the picture. I had to be careful tanking up, say in Washington State, as their fuel does have additives & is chemically treated there for their conditions & not the far North.

I will maintain the batteries with several trickle charges per winter, if I don't operate the engines. Fully charged batteries don't freeze. If a battery system is discharged, before the engine starts, then it needs to be re-charged to keep it from being ruined by freezing, so I take "engine starting" seriously. I still get 5 to 7 years of service from good batteries.

 

[sandcobra164]

Took my truck for a few runs today. Guess it is much different having a true diesel as opposed to a multifuel powered truck and I've been doing it wrong. Towards the end of each run, it would pick up speed to the point it'd run on the governor in 5th. After the third run, it idled without smoke. I put 25 gallons or more of fresh diesel in due to the 75 dollar cut-off at the pump halfway through the 3rd run. No more 50/50 filtered ATF/Diesel mix for me.

 

[sandcobra164]

I'm going on a shopping trip in the morning. New fuel filter, rubber lines, and such for the 5 ton. Good thing I still have the CUCV around for slave cable power if it takes too long to prime and crank. I also need to pick up a belt and some new light bulbs for the Tahoe so both lights are on when going down the road. After I get the big boy running again, I'm going to hold him on the floor and get a few hours of driving to ensure he gets everything sorted out.

 

[simp5782]

I'm going on a shopping trip in the morning. New fuel filter, rubber lines, and such for the 5 ton. Good thing I still have the CUCV around for slave cable power if it takes too long to prime and crank. I also need to pick up a belt and some new light bulbs for the Tahoe so both lights are on when going down the road. After I get the big boy running again, I'm going to hold him on the floor and get a few hours of driving to ensure he gets everything sorted out.

Let it idle the whole time you are gone to get the stuff. When you shut it down wrap the IP with a towel. Itll keep it warm and easy to bleed itself out for about 2 hours

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[sandcobra164]

Negative Simp,
I'm going to run it hard after the line and filter swap. Probably about 1/100 of the duty cycle you run yours at but 2 hours of hard running on fresh fuel should make this old Cummins happy!