300SDL: -10F start today, no block heater

[lotzagoodstuff]

I double checked all the GPs in the fall, and I do feel like the fuel system is 100%, but I am really impressed with how well this car starts in the cold here in Northern Illinois.

I am especially impressed when I consider that I am running Delo 400 15W-40 oil

Gotta love the old mechanically injected junk

 

[Shadetreemechanic]

I certainly don't have a benz that will do that. It was -1 this morning (i am at inlaws in upstate new york) and the benz fired up great after three hours with the block heater.
It has over 400K on it so once you get into the single digits it just spins and spins without even trying to fire. My guess is the compression is just too low at those temps to light off.

 

[lotzagoodstuff]

When it’s really cold, I’d say near 0 F or colder, mine cranks differently. Its hard to describe, but it cranks “faster” and “smoother”, which seems counterintuitive as one would think heavier cold oil would be harder on the starter. I always cycle the glow plugs twice when it’s that cold, and despite the fast spinning and somewhat lower initial idle it has never failed to start, even as cold as -15 F two years ago.

 

[Shadetreemechanic]

Mine does the faster smoother starter thing too. I have always guessed its because the rings are shrunk and the compression is lowered. Mine spins over fine, but never even tries to light off below zero.

 

[lotzagoodstuff]

I agree with your “shrunken due to the cold decompression” synopsis.

To further support your theory, it is absolutely the only time I feather the throttle when starting, which I compare to dry vs wet compression testing: wet is always higher.

Give it a shot with your Benz, you got nothing to lose.