Cold weather diesel starting

Yes, I know, this topic has been done to death. But still...
What is the lowest temperature one can reasonably expect a 617 engine to start given new glow plugs and an average battery?
Dropped to 10 F. here yesterday. It would not start. Called road service. Guy showed up with a dinky booster battery pack, no jumper cables. Well, of course it would not start. It would barely turn over at all with that booster battery. Later in the day when it was slightly warmer, we called road service again and this time he showed up with jumper cables. Took about thirty seconds to start.
Seems to me cold weather is a double whammy for a diesel. Even if the battery is in good shape at low temperatures it just does not have the capacity it does when warmer. So cranking runs it down really fast. If you cycle the glow plugs several times you are depleting the battery so the heat from the plugs is canceled by inability to fast turn over, which is essential. A slow cranking engine just will not start, unlike a gasoline engine where a spark just might get it going even if it is cranking slowly.
So, below what temperature is starting a diesel in otherwise good shape problematical?
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I would say it is your battery that is weak to begin with. I have started my diesel 609 in teens without any problem or any heater hooked up. I never used my engine heater.
If you have an engine heater, I suggest you use it... takes about an hour or so if it is outside.
That dinky booster battery pack is powerful... I have one myself and that started my diesel when my battery is dead. Yes, I changed my battery afterward.
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If I expected to be starting at those temps, I'd definitely want a relatively new battery, not an average one. Also, when were the valves last adjusted? The colder the temps, the more critical everything becomes. MB recommends a different valve clearance for use in areas where very cold starts will occur. If you have so-so battery, valves off, old injectors that are less than optimal, aged engine with less compression, etc, it all adds up to make it harder to start.
I've started mine quite easily in the high single digits, but that was years ago when the engine had a lot less miles. on it. More recently, I've occasionally started it at times in the teens. When starting at low temps, I apply partial throttle, which helps.
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In article
snipped-for-privacy@optonline.net says...

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We have had a very mild winter here. The 10 degrees yesterday is the first in two years. I used to actually take the battery out of the car and bring it home to keep it at room temperature. That always worked. But this time everything just got cold togther after a day running aroud in the rain with lights, wipers and heater on. Valves were adjusted in November. As the jump start from a battery in a car with the engine running showed, the battery just wasn't up to it.
How many time do you key the glow plugs in very cold weather?
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Only one time for my car... 95.
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This is something I've always wondered about too. Many here recommend cycling the glow plugs several times before trying to start the car in cold weather. I've rarely done that and can't say I noticed any difference. And if you think about it, I'm not sure it will do any good. All the glow plugs are really designed to do is get the very tip hot to serve as an ignition source. The indicator light is designed to go out about the time that has occured. After that, they stay on for probably another 2 mins or so anyway. So, I'm not sure what cycling them several times is going to accomplish. Certainly they can't raise the temp of the cylinder head much at all. And any air that is heated is quickly expelled and refilled during cranking.
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wrote:

Only one for my car as well. 84 with over 268k miles on it.
Although the glow plugs aren't an ignition source. They are a pre- heater. They heat the pre-chamber (a smaller cavity above the cylinder), which is where the fuel is injected into, and they heat it very well. They don't have to heat the whole block or head, just this pre-chamber.
As far as cycling them goes. I don't think it helps to do this. As you said, they stay on for a couple of minutes anyway. I have noticed that the light stays on longer when the ambient temperature is lower, and it stays on a very short period of time when the engine is warm, or outside air is warm. I have found on my car, that in below freezing temps, I need to wait a few more seconds after the light goes off, or just give a slight throttle when it starts. Otherwise, it starts first time every time.
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The glow pluigs are ambient temperature dependent. The light stays on much longer in cold weather than in warm. How much of a draw on the battery are they? If yu key them several times are you paradoxically ensuring that the car will not start because you have depleted the battery?
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Well, it certainly takes more juice out of the battery. Which is another reason I don't think it makes sense to do extra cycling. The glow plugs draw a whopping current, think it's like 80 amp range.
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What makes you think they even heat the pre-chamber? My understanding is they serve as a point ignition source. The very tip gets to around 1000 deg and that is what ignites the fuel/air mixture. I find it hard to believe the very tip of a glow plug tip is going to heat anything substantial that is made of metal, whether it be the pre-chamber or the cylinder head in 15 secs or so.

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single digit starting, never a problem. I get in, turn on the key, close the door, put on my seat belt, then turn it on. Occasionally, I'll have to cycle twice, but that's it.
-- Message posted using http://www.talkaboutautos.com/group/alt.auto.mercedes / More information at http://www.talkaboutautos.com/faq.html
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I've got a 240D, OM617, I think. If the engine soaks to 5-7F, that's it for me, even on a fresh charge. It's started fine after windy nites in the teens, maybe have to crank it twice, or keep a foot on the pedal for a minute in the teens. I'm not sure what my fuel is like at that temp either, but I've got cetane boost /anti cloud additive in the tank. I should probably cut w/ K1, that was our second cold snap like that.
In absence of a block or coolant heater, you might try leaving a hair dryer turned on in the engine compartment for a couple few hours.
Andy

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I've got a 240D, OM617, I think. If the engine soaks to 5-7F, that's it for me, even on a fresh charge. It's started fine after windy nites in the teens, maybe have to crank it twice, or keep a foot on the pedal for a minute in the teens. I'm not sure what my fuel is like at that temp either, but I've got cetane boost /anti cloud additive in the tank. I should probably cut w/ K1, that was our second cold snap like that.
In absence of a block or coolant heater, you might try leaving a hair dryer turned on in the engine compartment for a couple few hours.
Andy
When I was a kid (1950s/60s) my father had a small keronsene lamp type of arrangement, except the glass was replaced by copper mesh. He would put this under his car at night and hey presto it would start evry morning, Sounds like there's a market again!!
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I have a 1982 300 TDT with a 617 Turbo Diesel. I had the engine remanufactured at Metric Motors in the San Fernando valley last summer and I have about 6,000 miles on the new engine. It runs great. Starts instantly like a gas engine in a Toyota when it is warmed up, and starts pretty darn fast even when it's cold. I live in the Eastern Sierra, and our coldest temperatures in winter here at 4,000 feet don't usually go below 15 F or -10 C, but I have seen 0 F or -17 C. The new engine will start at on our coldest morning without a block heater, I think, but when I had the engine remanufactured I mentioned to Mike at Metric where I live and that I would like to get a block heater installed. He said he would just install one as part of the deal and did not charge me for it. It is installed in place of one of the freeze plugs on the right side of the engine just above and in front of the starter motor. It is the type which has a pump in it to circulate the coolant through the engine as well as heat it. If I know I am going to use the car in the morning I plug the heater in the night before.
I would highly recommend getting a block heater of that type installed if you frequently start your engine in cold temperatures. The engine starts as quickly and runs as smoothly right away as when it is 70 F or 20 C outside, which puts a lot less strain and wear on the engine. When you start your engine cold it takes longer for the oil to start lubricating everything and this causes a lot of wear on the engine. A friend of mine and his family own large commerical fishing vessels, and he tells me that they have block heaters on those engines that run all the time so if they need to start the auxiliary engine it is already warmed up and they do that because of concern over lubricants being cold at start not lubricating the very expensive large marine engines properly.
I try never to start my new engine without it being warmed up now. With the block heater plugged in I think this engine would start even if the outside temperature was -30 F or -34 C if you could get the fuel to flow.
I installed the new type glow plug relay from Bosch that comes back on when the engine starts and keeps the glow plugs on for the first 3 minutes of engine operation. This also helps the engine run smoothly from the start, which also lessens wear.
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Block heaters are a great idea. However, we park the car on a Manhattan street and there is no place to plug one in. I have seen provision for block heaters at parking meters in Fairbanks. You park the car, plug it in and feed the meter. I don't expect to see anything like that anytime soon in New York.
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wrote:

there is little reason to ever need a block heater in NYC, you can count on your hand the days it's gone below 10 degrees in the last few years there. In all my years of driving a diesel the only time I needed the block heater was when I was in Lake Placid NY and some of my glow plugs were out __________________________________________ Never argue with an idiot. They'll drag you down to their level and beat you with experience.
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Lots of ideas. Here are a couple more...
Lead acid batteries lose capacity as the temperature falls and motors become harder to turn as their oil thickens.
Battery: the size for a diesel is a Group 49 - this is a big, heavy battery, about 12" long. Be sure yours is this size.
If the existing battery is the correct size, you might consider buying some kind of smaller 12V Battery that you can (more) easily keep in the apartment and carry to the car to use as a booster (+ to +, - to -) for such cold start occasions.
Engine oil: The engine's oil ought to be diesel grade (CH-4 or CI-4 or CI 4 Plus) SAE 10 - 40. Single weight oil like SAE 30 or SAE 40 will be like tar at such low temperatures and really the cranking speed.
The 1980 300SD Owner's Manual instructs us on cold starting:
At ambient temp below 32 degrees F and with engine cold, completely depress accelerator while starting. Actuate starter until engine fires regularly and engine speed rises. Then ease off the accelerator slowly. Cranking times of up to one minute will not harm the starter.
At ambient temps below -4 degrees F, depress the accelerator three times prior to starting.
Check the oil pressure immediately after starting a cold engine and don't speed up the engine until pressure is shown on the gauge.
And if all this fails just park it over a steam grate!
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