Cold Start Performance
 

Just thought I'd add a data point. Went to work today, parked the car in the parking lot. Worked ten hours, plus a half hour lunch, plus got there a little early, so the car sat for about ten hours 45 minutes. Temperature 11 degrees F. Elevation about 4700 feet. The car is an '83 300D with 336,000 miles, compression unknown (I'm afraid to find out.), about 17,000 since the last valve adjustment (I know:o), 5W40 Rotella T6 synthetic, no block heater (not that my work has any place to plug in), battery not the newest, starter originally purchased from Auto Zoo in 2010 for the 240D I had at the time. Three tries, tons of smoke, and a slower than normal but consistent cranking speed, and I got it going.

Excellent.

I read on here that the engine will lose all its retained warmth in about six hours, in those conditions.

Sounds to me like your starter is working better than mine (and your battery is still in good shape). The lynchpin is the synthetic. Oh and you must have done a bang-up job on that last valve adjustment :D.

what is your exact starting procedure?
"three tries and tons of smoke" did you actually attempt cranking three times?

the best cold weather tip I know for starting a diesel without block heating is...

RUN THE GLOW PLUGS TO THE LIMIT UNTIL THE RELAY CLICKS OFF 3 times in rapid succession, then hit the starter, and hold it until the motor fires and accelerates beyond the starter.

if the fuel spray injected into the cylinder is allowed to cool, it will be doubly hard to start on the next attempt.

also, glowing after the starter has attempted to spin will further deplete the battery making it that much harder for the starter to begin spinning all the motor mass.

once the motor is spinning, the mass helps the starter overcome the compression, and the maximum rototation is achieved, resulting in the most heat for the best possible burn.

Also hope that one's foot is on the floor, there's a youtube video of someone trying to start a 617 and nearly melting the starter all while the accelerator linkage is still in the idle position...

617.95 observations over 22 yrs starting below freezing -40 degs C good outdoors for 4 hours and starting with 2 glow cycles before cranking for 5 seconds.
-30 degs C good for 5 hours again 2 glow cycles required.
-20 degs C good for 6 hours with 2 glow cycles required.
Extend the time and some sort of heat is required.

They tend to start easier and better than vw diesels of the same era.

-40C..now that's cold!:santa3::santa3::santa3:
The one spot on the thermometer where Fahrenheit & Celsius are the same.

Don't forget to make sure you have good glow plugs, too.
Mercedes Diesel Glow Plug Repair

Jeff

First try, the usual for cold weather, since I didn't realize how cold it was: Turn key to glowplug position, wait for the light to go out, then wait a few more seconds, then crank. After about ten seconds cranking no cylinders were firing and I decided to start over.

Second try: Turn key off and back to glowing. Wait for the light to go out and then wait a few more seconds, then crank. After ten or fifteen seconds of cranking cylinders were firing to the point I thought the engine would run on its own. Nope.

Third try (while thinking about the jumper cables in the trunk and wondering if I'd have any trouble getting a jump): Cycle glowplugs again. Wait a few seconds after the light goes out to begin cranking. Crank while giving it half accelerator travel for a few seconds, then floored, then going back to half while getting a bit of cylinder firing the whole time. After about 20 seconds of cranking the engine began to overrun the starter and I let go of the key.

At this point I realized I had covered half of a rather large parking lot in white smoke. I drove away wondering why I'd had such a hard time starting and got a clue several miles down the road when one of those signs that tells you the temperature said 19, and that one always reads suspiciously high. I determined the actual starting temperature from weather.com.

Yall know that you can mix 20 percent gasoline in your tank for Really Cold operation....

and that the FSM has a chart showing the temperatures the glow plugs get to all the way up to at least 45 seconds.... and they suggest leaving them ON that long in really cold weather..
I do not know whether the plugs get turned off automatically when your light goes off... or when you hear a click...or if you leave the key in the glow position the plugs will continue to their designed high temperature... and I wish someone with gravitas would answer that question.. it might help a lot of people in the cold...

They stay on after the light goes out. How long? Not sure. Today I tried waiting until I heard a click before cranking. The car started right up, but it had only been sitting three hours.

I wouldn't say that's the best procedure unless you're trying to prove something. Why not glow 2 or 3 cycles BEFORE you even crank?

That's what I do. Glow until I hear the click (25 seconds or so). Immediately glow another full cycle. Then glow until the light goes out and start. If it's in the 30s I might skip the second cycle.

Of course, I try to remember to use the block heater when it's in the mid-20s or colder. I hate the idea of that cold oil thickening and not lubricating as well as it should.

I observed in both a 123 euro 300tdt updated GP and my 124 2.5td chillier than -20 they glow for 45 seconds and remained on for an additional 90 seconds after starting. During cranking they are on. This is with a cold engine. The specifications I once checked long ago were in agreement.

In colder temperatures it is not uncommon to see equipment run for several months continuously in fear of a no start and construction would have to wait. Many half tons seem to fall into that category also.

Because the wind wasn't blowing and I had just been doing some heavy manual labor so I thought it was maybe mid 20's out.

I timed timed my daughter's 84 SD and my 83 300D. Both the glow plug relays quit around 26 seconds. Fwiw.

I replaced some champion glow plugs recently that I discovered afterwards were still functional, however it took them a little over 20 seconds to get hot enough to glow. No wonder the car was so hard to start!

Regards,

W

That starter is not as strong as one for a 300 turbo, but works.

The attachments are from the owners manual.

I wouldn't use gasoline at all.