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Cold Starts, Winter Prep
With the approach of each winter in New England, and having driven a 123 diesel since 1997, I have over time developed my ongoing list of winter preparation measures....here it is....in general order of importance
Part I - Diesel Engine Starting...there are many things that work in concert to facilitate reliable winter starting...also note, on these old cars, there are some factors that we must simply "work around" trying to maximize cold starting. Very few of us are going to rebuild and calibrate the fuel injection pump. And very few of us are going to rebuild the engine (lower end) or even do valve job (upper end) to maximize compression. But with good general maintenance on these cars, for the life of the car, you can get 500,000 miles without engine rebuild or injection pump rebuild, and maybe even without a valve job(?). For those of us who have cars that were not treated well in their earlier years, we may suffer the unavoidable consequences now. But for those of us who inherited cars that were well maintained, there are many things we can do to maximize cold starting and general engine performance. 1. Compression - regular valve clearance adjustments are critical. I do mine around three times each year...with 375,000 miles, I am hoping to get a half-million miles without ever needing to remove the head (for valve job). Note that if lower end is shot (rings, etc.), valve adjustments aren't going to have much impact on improving compression. 2. Glow Plugs - nice new glow plugs heat fast and hot. After a few years, they start to lose their "oomph". As a general rule, I replace glow plugs every 3 years. For general maintenance, every fall, I remove glow plugs, clean off carbon, and ream holes to remove carbon....(carbon buildup absorbs heat reducing effectiveness of glow plug). 3. Battery - a nice new battery will turn the starter faster (and longer). After a few years, I find that the starter rotates a little more sluggishly. (I replace my battery every three years.) Rapid turning of the starter will give better/faster "kick" (compression buildup) in combustion chamber to start the thing. 4. Injectors - simply stated, if one or more of your injectors are squirting a stream of fuel rather than a nice atomized cloud, starting will be more difficult (not to mention carbon buildup, poorer performance, etc.). A couple years ago, I got new Monark nozzles, and had the pop pressures set to spec. at a local diesel shop, and I couldn't believe the dramatic improvement - better cold starting, nice smooth idling, better fuel economy, etc. I would bet that the majority of people driving these old Mercedes diesel have poor injectors.....by replacing injectors (or nozzles) and making sure they are adjusted properly will have a greater impact on performance than any other one thing you can do! Torque properly with new heat shields. 5. Synthetic Oil - during warmer months, I use regular dino 15W-40 oil (5K mi intervals). But every December I put in 5W-40 synthetic to facilitate rapid turning of the motor during cold starts. I don't change it till beginning of March, even if I have well over 5K mi. (extended oil change interval is OK with synthetic, but you may want to throw in a new filter at around 4-5K if you're going push the interval to over 8-9K) 6. Electrical - Make sure all your electrical connections for the starting system are clean....battery terminals, neg. battery cable to body ground, pos. battery cable to starter, both ends of ground strap, and wire connections in that little box on the wheel hump just forward of the battery). (This may be a little overkill, but a couple years ago, I upgraded battery cables and ground strap to 2 gauge size....I used welding cable and other materials, with soldered copper 2 gauge connectors....my main motivation was to facilitate max. current flow for cold starts....probably overkill, but fun to do. The main thing is clean all connections.) 7. General Maintenance - regular oil changes (5K mi), fuel filters (annual), engine timing (start of fuel delivery), diesel purge (annual). Its also good to make sure your fuel tank screen is not clogged, and put in mold biocide once a year...do this about 2 weeks prior to annual fuel filter change. 8. Proper starting procedure - when its very cold (approx. 10 deg. F or lower), you want to maximize your chance that the engine will start before killing the battery or frying the starter. Go through 2 or 3 full glow plug cycles (not just when dash light goes out....go through the FULL cycle...wait till you hear glow plug relay click off, then repeat). Then with pedal to the floor, turn the starter and hold till it "catches," but try not to turn the starter more than 10 seconds, or you risk frying it. Also, make sure all other electricals are off, to minimize unnecessary draw on the battery. 9. Battery Pack - I built a battery pack using a 12V 26.0 Ah rechargeable sealed lead acid battery. On real cold cold mornings (0 or below), I connect this to the battery before even trying to start the car, maximizing the chance that I can start the car before I kill the battery. 10. Block Heater - obviously, if you plug in a block heater at night, all the above measures become moot. I built a little box on the outside of the house for my extension cord, and the outlet in the box is connected to a timer in the basement. I plug car in every night during cold weather, and timer goes on at 3 am. I do this even with low temps in the 20s...as a long-term measure to minimize engine wear from daily cold starts. Part II. Other things to do to prepare for winter 1. Engine coolant - I use Mercedes antifreeze, 50/50 mixture, change and flush every three years. 2. Snow tires - I am a firm believer in running four snows in winter...I like Firestone Winterforce (without studs)...cheap, aggressive tread. I have them mounted on separate wheels, and change them myself (I'm not going to pay for mount and balance twice a year!). I get three seasons out of a set of snows. 3. Jumpers - I built a nice set of 22 foot jumpers using 2 gauge copper welding cable, and keep them in the car all winter, just in case. Best for these cars is 2 gauge copper or larger. I also like long jumpers, in case you parked facing in, and need to reach vehicle behind your car. The long length of the jumpers is another reason for heavy gauge. 4. Monovalve - I find that the monovalve fails about every 3 to 5 years. So, within a couple of years after installing a repair kit, I make sure I have a spare in the car at all times. I do this because one winter, the monovalve failed right when I had a 6 hour drive home....that was a LONG, COLD ride home! Installing a monovalve repair kit on the road is very easy. 5. AC maintenance - Most people think of AC as a "comfort factor" for summer driving. This is true, but AC is also a very important safety factor for de-fogging windows especially in winter....occasionally, if my AC performance is marginal, and is in need of a recharge, I will "top off" refrigerant in preparation for winter, and delay the full maintenance (vacuum, recharge, change receiver/drier) until the following summer. 6. Lights, Flashers, Flares, etc. - Having spare bulbs (headlights, brakes, flashers, etc.) and having some emergency flares, reflectors, etc. on hand is important all year long, but especially in winter when visibility and road conditions are worst. 7. Lock cores for doors & trunk/hatch - take out cores, remove and clean leaf tumblers & springs, and lubricate. These are notorious for freezing up in winter....keep a little can of lock de-icer and/or a propane lighter in your pocket at all times in winter! 8. Wipers - I never liked those sealed winter wipers...they just don't work that well. And I do not change wipers in preparation for winter, because the icy windshield just tears them up (I change wipers in spring). But in preparation for winter, I do adjust spray pattern, clean out spray nozzles (stick a pin in there, or blow out with compressed air). In winter, I also add a little dry gas (pure methanol) to washer fluid. 9. Fall Preventative Maintenance (PM) - Fall is the time to check several things on your car....for those of you without garages (like me), you want to avoid major repairs in winter (one year, I changed a starter motor at night in January out in my driveway with temps in the teens!) Some winter repairs are unavoidable, but Fall PM can save you some real headaches. - Check your brake pads when you put on your snows - Exhaust system, hangers - Engine belts - Vacuum system (especially that damn footwell vacuum element!) - etc. Anyway, that's enough for now...I'm sure I forgot a few things. Also, please note that the intervals for various things are my own personal choices based on my own experiences, the harshness of my winters, the fact that my car is my daily driver and I rely on it for work, and other things...these aren't necessarily applicable to everyone...for example, if I was in Florida, I wouldn't be changing the battery every 3 years! Please add to the list! Happy Holidays, and Safe Winter Motoring! Mark
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1984 300TD Wagon, 407,800 mi (current daily driver) 1985 300DT Sedan, 330,000 mi (gone to that great autobahn in the sky) |
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10. on how to prepare for winter...Fly to Hawaii
Thanks for the great list though. I was amazed how much better my 7.3 started last winter when I went from Delo 15w40 to Mobil 2 syn 5w40, it was like a completely different animal and fired up like it was the middle of June. It really is great stuff. |
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X 2 on both counts!
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Brad 1981 300TD - daily driver 1963 Chevy II 2001 F-250 7.3 Power Stroke |
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Thanks....that's really helpful.
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14 E250 Bluetec "Sinclair", Palladium Silver on Black, 153k miles 06 E320 CDI "Rutherford", Black on Tan, 171k mi, Stage 1 tune, tuned TCU 91 300D "Otis", Smoke Silver, 142k mi, wastegate conversion 19 Honda CR-V EX 61k mi Fourteen other MB's owned and sold 1961 Very Tolerant Wife |
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In reference to putting the pedal to the floor when cranking...is this benefitial?
I've never done it. I was under the impression that it was unnecessary in our old diesels. Maybe not doing so will explain why mine catches but dies a coughing death a few seconds later. Thoughts?
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1974 240D "Boldie" 170K.- New timing chain/freshly rebuilt IP/replaced valve seals/injectors/upgraded stereo/new Bilsteins with Yokohamas/fresh paint and rocker panels plus lots of welds. |
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Agreed
Agreed on trip to Hawaii....sorry to say though, that I have to settle for something a little more frugal for winter prep....like maybe a flask of single barrel Jack!
Another winter prep item for these cars, since I don't think you can install a remote car starter, is: "teach wife how to go out and start the car for you on a cold winter morning" One thing I was thinking of doing is install a little box for a spare key, and maybe a "lock thaw kit", on the cowl-like platform just forward of each front wheel....something bigger and better than one of those magnetic key boxes. Maybe a small waterproof pelican box. I would spray paint it flat black, and maybe put a few "decoy electrical wires" or something on it so its out of site and looks like a regular vehicle component. In addition to spare key, that would be a good place for can of lock thaw, propane lighter, etc. ...maybe a peanut butter sandwich. I know what happens....when I really need to thaw the door lock, I don't have anything with me to do it. As far as proper starting procedure, e.g. pedal to the floor or foot not on pedal, that was one of the items on my list I wasn't sure of...I will check for proper MBZ recommendation and get back. Anyone else know? Mark
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1984 300TD Wagon, 407,800 mi (current daily driver) 1985 300DT Sedan, 330,000 mi (gone to that great autobahn in the sky) |
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On the pedal to the floor: In my experience, this has been a bad idea. It floods the cylinders with a lot of cold diesel, cooling it down and inhibiting starting. I don't touch the pedal unless it starts running on one or two cylinders, then I hold it to the floor to keep it running on those cylinders until the other start firing while keeping the starter turning.
Mercedes is explicit about keeping the starter going until the engine can run on its own. You don't want to think of these starters like gasser starters. They were designed to work hard in cold weather and assist the one or two cylinders with rotation until more cylinders resurrect. Your best shot at getting 616's or 617's started in really cold weather is the first one in my experience. Second or third attempts are much more likely to be futile. Give it all you've got on the first round. Multiple glows and a commitment to keep the starter turning until the engine runs or the battery dies. Any weakness of will on that first attempt will likely ultimately result in failure to fire.
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1977 300d 70k--sold 08 1985 300TD 185k+ 1984 307d 126k--sold 8/03 1985 409d 65k--sold 06 1984 300SD 315k--daughter's car 1979 300SD 122k--sold 2/11 1999 Fuso FG Expedition Camper 1993 GMC Sierra 6.5 TD 4x4 1982 Bluebird Wanderlodge CAT 3208--Sold 2/13 |
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Agreed
Quote:
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1984 300TD Wagon, 407,800 mi (current daily driver) 1985 300DT Sedan, 330,000 mi (gone to that great autobahn in the sky) |
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