Is this okay? Holding the Pedal to Start? - PeachParts Mercedes-Benz Forum

#1 10-30-2002, 08:33 PM

It's been cold in Jersey these days and my 300 has been hard to wake up. Frankly, I don't blame her, but she is hard to start. The only way I can get it to start is to lightly hold my foot on the gas pedal. Is this okay? I mean, the valves have been adjusted, I use DFC. What else is a commuter to do????

kerry · #2 10-30-2002, 08:40 PM

No wonder it won't start. You need to push on the 'diesel' pedal and not the 'gas' pedal.
Seriously, if you have the older style glow plugs, wait 40 seconds after the light goes off and see if it starts any easier. On my 77 that delay makes all the difference in cold weather starts. Make sure you have synthetic oil in it. Plug in the block heater if those tips don't help.

Ridge · #3 10-30-2002, 08:55 PM

Randal,

All the older 300Ds and 240Ds had a small twist knob to the left of the steering wheel so that you could dial in a little throttle before starting the car on a cold morning. So what you're doing certainly shouldn't hurt. In fact, you may want to look around for one of those controls and retrofit you car. They're very easy to install in if you were to look at the backside of your dash in that area, you'd probably find that all you'd need to do is cut through the black vinyl to install the unit in the dash. In any case don't worry. Two of my five MBs have the adjuster.

Ben

rickjordan · #4 10-30-2002, 09:27 PM

Mercedes stopped using the manual idle adjustment in 1979. Randall, are you plugging in the block heater yet? What weight oil are you using? Even though your glowplug light may be working normal, check the glowplugs with a meter anyways.

diesel don · #5 10-30-2002, 10:00 PM

I start all my MB's with the pedal fully depressed. If this is incorrect, someone let me know.

Don

Holson Adi · #6 10-30-2002, 10:17 PM

I don't but maybe that's because last winter wasn't so cold and now it's garaged.

Anyway, the Toyota Landcruiser Turbodiesels have this 'idle-up' feature too... I always wondered what it was for. Stupid me.. we never needed it in Jakarta, Indonesia where it is 89F all year long.

#7 10-30-2002, 10:49 PM

Yeah, I remember those old idle adjustment knobs. I liked the feature.... So, I guess I'm not all too crazy.... Just, I know that in old Porsche 911s, pumping the throttle while starting will blow up the air box. Clearly not the case in the 300Ds.... I believe my car now has sythetic 10w30 oil, no block heater... Thanks guys!

#8 10-31-2002, 06:46 AM

'79 was not the last year for the dashboard idle adjustment. This was on most all 123's. My '84 has it, my daughters '81 has it.

Have a great day,

dieseldaddy · #9 10-31-2002, 08:09 AM

...As does my 83 240D (even though it is not functioning)

wheelguru · #10 10-31-2002, 11:01 AM

I was perusing my owners manual last night to find out how much transmission fluid goes into my car and came across the official starting instructions. For my '78, the manual says that if it is between 64 and 32 degrees you push the pedal halfway down. under 32, pump it once and leave it halfway then turn the key, under 4 below, pump it three times and leave it down when you turn the key. Don't know if it would be any different for a turbo model.

kerry · #11 10-31-2002, 12:59 PM

In very cold weather(10 degrees and below) I have found that holding the accelerator about halfway down while cranking is helpful. A few cylinders will fire and I keep the starter running until the rest kick in. I would not do this on a gasoline engine but I read somewhere (perhaps in my manual) that Mercedes diesel starters are designed to be used in this manner.

#12 10-31-2002, 01:11 PM

I do not have an owners manual , and was very surprised to read here where the manual recommends pumping the pedal. Is that correct? Does the IP have a sort of fuel pump that works like carburated gassers?

wheelguru · #13 10-31-2002, 05:42 PM

it really says it, but from the little that I understand of the IP I can't imagine why either. maybe someone else knows. I have tried it both ways when it is really cold out and I can't tell a difference. -andy
ps, the manual says to pump it three times before you turn the key, you just keep the pedal down after you engage the starter.

dabenz · #14 10-31-2002, 06:38 PM

Randall, no problem to hold the foot throttle in when starting. Pumping won't do any good when the engine/injector pump is not turning. I wouldn't pump when the engine/injector pump is turning either, even though some of these pumps are built to give an extra shot when starting. Iit won't be enough to keep it running. Just push the foot throttle in a bit more if/when it stumbles and hold it there until things steady out. Also: did you change your fuel filter as part of your winterizing stuff? Check glow plugs? Glowing many times takes less juice than cranking a cold engine. Engine oil? Somewhere around here I put up some winter fueling tips.

Now, if you have a newer drive-by-wire engine like the VWs and new trucks then the best place for the throttle foot is the passenger seat when cold starting, because the computer does all the thinking.

jcd · #15 11-01-2002, 06:27 AM

"At ambient temperatures of less than -4F, depress the accelerator three times before starting."

"At ambient temperatures below +59F and with the engine cold, depress accelerator at least half of its travel while starting"

"At ambient temperatures below +23F and with the engine cold, depress the clutch pedal completely and the accelerator at least half of its travel while starting."