Per Brian's recommendations in reply to my first "cold weather freakout" thread, I'm running fresh 5w40 Mobile1 Turbo Diesel synthetic. The one bad glow plug was replaced, and all glow plugs now register under .2 ohms resistance.

Good point with regard to jumper cables Brian. Mine are 8 gauge heavy duty, but the clamp connectors are always awful, and these are no exception. Still, its sometimes the difference between being able to start and not being able to start for me. I always have the other driver keep his engine revved, which keeps the baseline voltage an extra volt higher, and I swear by that little difference (even though I dont have fast enough tooling to measure whether it actually has positive impact counteracting the voltage droop of crankover).

Yes a battery replacement is in order. However I've noticed the starter sounding really pathetic for a while, and the local Benz shop commented on its sound the last time I brought it in. At this point, I feel the starter is in worse shape, and am going to replace it first, before the battery.

Let me see.........time to R & R battery: 30 minutes.

Time to R & R starter: 2 hours.


If it were me..........I'd do the battery first...........you cannot judge a starter's performance when you have a weak battery.

With respect, I see the breakdown in slightly different terms:

Money spent replacing battery then starter: $240
Money spent replacing starter: $170

Per time, yes, replacing the battery is the most logical next step. Looking at monetary risk though, I think this battery still has another couple years left in her, assuming that power is going somewhere useful, so replacing it can be delayed.

How are you drawing a distinction between a bad sounding starter from a weak battery and a bad sounding starter with a strong battery?
Why not test the battery by swapping in a known good battery and giving it a try?

__________________
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

Brian & Kerry,
You are on the money!! Always try another battery, clean terminals, tight connection on starter & good leads. All these things need doing anyway. If that dont work, then maybe starter is a problem.

Even if the battery itself were non-optimal, the steps I've taken to counteract any badness certainly should be enough for the starter to have a very reasonable chance to prove itself.

Having been saved from a number of over-cranked low-battery situations by jumps, I still believe getting a jump-- particularly with good cables, from a high revving vehicle with a known really-good 200+ amp alternator, with considerate clamp mounting-- offers a very significant leveling between a perhaps-bad/drained-power battery and a nominally operating power supply for the starter.

Taking every measure I can, including overnight battery charging of the "bad" battery with a very good intelligent 50a charger and then doing a Best-Effort jump first off, the starter still cant so much as blip the tach.

I've managed to jump one of our diesels with the other, with good cables....but I let the power-donating vehicle idle connected to the dead car for a good 10-15 minutes before I even tried cranking. That was in moderate temperatures....25-35F or so....

I've jumped my car at -15F before with my charger/starter unit. I connected it at a 20Amp charge for about 25-30 minutes, then I flipped it to 100A start mode, quick glowed, and cranked, and it turned over faster than ever before! I had it running in about 3-4 rotations at less than -10F!

__________________
-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)