I have 341,000 on my 85 300D. It got to about 28 F here for the past 2 mornings. I almost could not get the car started and am afraid of low compression. I have listed below what I did/have done. Another important question is should I be expected to use the block heater when the temperature gets this cold and this many miles on a turbodiesel engine?

1. Valves adjusted 8,000 miles ago.
2. New battery 2 weeks ago
3. Pre-glow through 3 cycles (until the relay clicks off before trying to start).
4. Hold the accelerator completely to the floorboard while cranking.

Any suggestions greatly appreciated!

Richard

Have you actually checked the glow plugs to see if they are all working?

It probably would not hurt to use the block heater at temperatures. I have not plugged my 91 300D in, it started this morning at 8F without incident.

Its entirely likely that you have one or more glow plugs dead/not working.

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82 300SD 145k
89 420SEL 210k
89 560SEL 118k
90 300SE 262k RIP 5/25/2010
90 560SEL 154k
91 300D 2.5 Turbo. 241k
93 190E 3.0 235k
93 300E 195k

Have you tried cranking without touching the pedal? I know it's contrary to the procedure in the manual, but I find my car starts at low temps better if I leave the pedal alone, at least until it starts running--then it helps to up the RPMs just slightly until it smoothes out.

But JamesDean is right about the glow plugs. I put a new set of Bosch Duraterms in this past fall and the difference is huge.
Mercedes Diesel Glow Plug Repair

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05 E320 CDI - 175K miles
82 300D - 200K miles (sold)

I live in Canada, and often have to start car in much lower temperatures than that.

If car is in a garage, as mine usually is, it will start without block heater at 28F. If outdoors it seems engine gets colder and battery output is lower. then block heater is needed.

Essentials:
- Good compression
- Properly adjusted valves (I once had shop do them and they had them all wrong)
- Properly working glow plugs. May need to ream out pre-chambers
- Good fuel.

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Graham
85 300D,72 350SL, 98 E320, Outback 2.5

If you wait until the relay clicks off, the glow plugs will not be energized when you turn the key to the start position. You should move the key to 'start' before the relay kicks off so that the plugs are on while the engine is turning over.

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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

You don't mention the age of the glow plugs. If you are glowing multiple times and it barely starts, I think you either have weak glow from old GPs, or at least two not working at all. As long as the #1 plug is working, the glow light will show on the dash. That doesn't mean you have adequate heat.

My experience has been that here in cold eastern Canada, valve adjustment issues often show up before the temp you describe. As Graham pointed out, around here 28 F (-2 C) is hardly even a cold day at this time of year. The motor would have to have very low compression figures to refuse to start at that temp. (I know -- I drove a high-miler 300sd with a pooched motor through one winter.)

Tonight in my area we are going down to -31 C (-24 F) and the windchill factor will be -42 F.

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Mac
2002 e320 4matic estate│1985 300d│1980 300td
Previous: 1979 & 1982 & 1983 300sd │ 1982 240d

“Let's take a drive into the middle of nowhere with a packet of Marlboro lights and talk about our lives.” ― Joseph Heller, Catch-22

As mentioned, good glow plugs are a must.

Synthetic oil too.

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83 SD

84 CD

And a good starter!

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