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-   -   Diesel Cold Start (http://www.peachparts.com/shopforum/tech-help/54969-diesel-cold-start.html)

kpfmpf 01-18-2003 12:42 PM

Diesel Cold Start
 
I HAVE A 1979 240D. UNFORTUNATELY THE PREVIOUS OWNERS FAILED TO PUT A BLOCKHEATER. WHEN IT GETS BELOW 24* F THE CAR SIMPLY WON'T START (IT HAS LOOP TYPE GLOW PLUGS) I TRIED TO OPEN THE SPACE BEHIND THE STARTER TO INSTALL A BLOCKHEATER, BUT CANNOT BREAK THAT BOLT. WILL CONVERTING TO PENCIL TYPE BLOCKS HELP AT ALL? SOMEONE TOLD ME TO CONNECT A SECOND BATTERY IN SEQUENCEWILL FIRE THE CAR UP AT ANY TEMPERATURE IS THIS TRUE?:confused:

ILUVMILS 01-18-2003 03:38 PM

If all is well your car should start with no problem at 24F. When starting problems occur on MB diesels most people immediately look at the glow system. This is logical, but valve adjustment is quite often the cause. I've seen it dozens of times over the years.

RandyR 01-18-2003 07:09 PM

Well I hate to say this , but when we had a fleet of garbage trucks (including two Mercedes garbage trucks) we gave them a shot of either. A shot, always started,
20 below, 5am, always started.

Now I know that either is against the religion of many of you but, I also know you'll have sinned before and I'd rather give a shot myself than let a tow truck driver do it. Keep a can in your trunk incase you have the need to sin.

Now, if your out of town and the weatherman is saying 30 below and you know it isn't going to start in the morning . Get an extra key and let your diesel idle all night. One in the ignition and one in the pocket after locking the car. Just run it up the highway the next day and get rid of some of that carbon.

Regards,

Randy Roeges

ThrillBilly 01-18-2003 09:35 PM

"summer" diesels
 
i feel your pain! i have a 300 turbo that would NOT start when the temp went below approx 20 deg F. i installed a block heater (the plug and wiring was already in place) and plug her in when really cold temps are present. that solved all my cold starting problems.

when the prob 1st showed, i went to my trusted mech, and he said: "your bought yourself one of those "summer" diesels." :eek:

anyway... the problem is mostly related to compression. i could crank forever with a great battery to no avail. if the compression is not high enough, it will NOT generate enough heat to fire when the block is REALLY COLD. it also helps to add a D-fuel additive such as redline during the winter.

get a heater installed, plug it in, and sleep well KNOWING that your diesel will fire instantly whenever you desire to go!

i seem to remember paying about $35 for the heater installed.

or... i was in key largo last week, and im sure your diesel would fire any day in a similar climate! :cool:

Robert W. Roe 01-19-2003 03:46 AM

Switching to a synthetic oil helps the engine crank faster when it's really cold. Since switching to the Rotella Synthetic I haven't "had" to use my block heater at all. I just started the SD in 15 degree weather after it had been sitting a couple weeks. No problem. Before, with 15W40 dino Rotella, I had to crank about 20 seconds at 8 degrees once to get it to kick over.

jcd 01-19-2003 09:51 AM

Check the owners manual for starting instructions in cold weather
 
My 1977 300D sat for two days in NJ with temps at night in the single digits. It was around 10 degrees when I gave it a crank, and my battery is a little low on juice.

Owners manual states, "at ambient temps below +23 F, depress the accelerator at least half of its travel while starting".....also "at ambient temperatures below -4F, depress the accelerator three times prior to starting".

I used the -4F approach and it fired right up.

Althought I think a block heater is a good thing and synthetic oil helps, but if the valves are adjusted properly, glow plugs are operable, the beast should start.....but the method used does make a difference.

JCD

artpb 01-19-2003 10:38 AM

Re: Diesel Cold Start
 
Yesterday Morning it was 4 degrees here in Buffalo. My procedure for the 1983 3oosd is to Double Glow then depress the pedal 1/2 way once and turn the key. Started right up. I do use Mobil 1. Prior to this my car had sat for a week.

I feel glowing twice is important because you have to overcome the effects of moisture in the combustion chamber. More pronounced in cars that don't have everything just right or have less than optimal compression. Cars parked outside seem to have more of a problem starting then those that are garaged.

Prior to my current ownership I have owned a 1975 240D and a 1979 300D. Both these cars would start ok down to abt 20 degrees. So I used a block heater plugged into a timer and determined they would both start up great after abt 2 hours. The big plus here was almost instant heat.

Good luck - art

Ed Richardson 01-19-2003 04:12 PM

According to Frank King, the former guru of the MB Club, the glow system remains active for several seconds after the glow light goes off, or until the starter is activated. Therefore, double glow and leave the system on for for 30 seconds after the light goes out, then start.
Another item, in addition to valves, etc, is to check the starter. It turned out that was my problem, my starter was tired.

kerry 01-19-2003 08:28 PM

Use synthetic oil. Make sure battery is strong and starter spinning well. Then wait 40 seconds after the glow light goes out before starting. That extra 40 seconds makes all the difference in the world in my 77 300d. It won't start without that 40 second wait. Don't be afraid to keep the starter engaged if it initially only fires on a couple of cylinders.
Also, adjust the valves. If all else fails, do a compression check.
I have heard repeatedly that it is not wise to use ether in a diesel with prechambers. I would not use ether myself. You could introduce some hot air into the combustion chambers with a heat gun or a propane torch shooting into the air intake.

kpfmpf 01-21-2003 10:09 PM

Thank all of you for your great advise. I switched immediately to Synthetic. It really made a difference. I also practiced to wait 20 seconds after preglowing twice, and the car starts up now. Tomorrow morning we will be at 11*F and I will run the car tonight around 11p for 10 minutes. If not I will try the "illegal" shot. I tried to remove the plug behind the starter to install a blockheater, but since the engine is the original 79 and has about 330k on it, the plug won't budge, including paint thinner, Caramba and torch. My neighbour works at an autoparts store and has told me that there is a heatable dipstick insert that will warm up the oil. He says the hot oil will in turn warm the engine after only a few cranks. He says he hasn't seen one in years and will hunt one down for me

THANKS AGAIN TO ALL OF YOU

KARL ;)

rbauman 01-23-2003 03:45 PM

In cold weather, a block heater will provide a rapid start ( of course it does). Inaddition, it will reduce engine wear and provide earlier heater use for occupants. Without a block heater in my 1983 300CD, I could start it with most of the already mentioned procedures (preheat, synthetics, etc.) in temp down to zeroF. Good thoughts guys


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