I did state If everything is perfect:

Durability testing proves that excess thermal loading begins/happens after 60 seconds of full load cranking on a perfect NEW starter.

If it does not start by then = there are issues that need to be fixed..

Copied verbatim from original MB “Owners Manual” for 240D/300D

"At temperatures below 0°C and with the engine cold, completely depress accelerator and clutch pedal while starting. Actuate starter until the engine fires regularly and engine speed rises. Then ease off the accelerator slowly."

This is a standard V cold start practice (< -10°C) and applies equally to all old indirect injection Diesel engines equipped with glow plugs and inline fuel pumps.

There is a very good reason for this – It ensures that you are getting sufficient fuel injected on all 5 cyl’s on that critical first cycle. Fuel volume @ full boost full throttle is 44mm³ / cyl on the 617 engine (about the size of a 4mmØ ball) and at idle just a very small fraction of that!

Regarding The Pre-glow:

Quote FSM - “After a glow period of 9secs a temp. of 900°C is attained and after 30secs the max. temp of 1180°C is reached. Cut-out between 30 sec and 1 min depending on ambient temp.”

There is little point in glowing for more than 15 sec and in any case it should be less than half the glow cycle time to allow start before cut out. The glow plug is the primary source of ignition for a very cold start and after cut out you will be relying solely on auto-ignition.

Just BTW: The auto-ignition temp of #1 Diesel is 210°C, almost 40°C lower than #2 Diesel.

__________________
Beagle

That is on a NEW "PERFECT" engine.

The FSM also tells you to use gasoline for better cold starting, there is a TSB that superseded that, and now specifies kerosene.

As to the extended glow or double glow, my data is correct.
Later models incorperated the after-glow function into the glow plug relay for easier starting and emissions.

The hotter the pre-chamber = easier start.

__________________
ASE Master Mechanic
asemastermechanic@juno.com

Prototype R&D/testing:
Thermal & Aerodynamic System Engineering (TASE) Senior vehicle instrumentation technician.
Noise Vibration and Harshness (NVH).
Dynamometer.
Heat exchanger durability.
HV-A/C Climate Control.
Vehicle build.
Fleet Durability
Technical Quality Auditor.
Automotive Technical Writer

1985 300SD
1983 300D
1984 190D
2003 Volvo V70
2002 Honda Civic

https://www.boldegoist.com/

I don't see that method working with mine; any throttle at all makes it more difficult to fire initially. I have started mine at about -5F, but I had to pre-glow several times and crank for a while (with no throttle).

Last week It got down to 17 gegrees here. Car sat out all night and was not plugged in. My battery was very weak, thus no starting. New battery and car fired instantly after glowing two full cycles. I did squirt WD-40 in the air inlet just before cranking. I'm not sure if the WD-40 did any good.

__________________
www.myadvoforum.com
http://advopal.com

My car stars fine, but if I leave the car in park or neutral the idlestarts lobbing ( goes down and up). I figure this is the lift pump. Any ideas?

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-Typos courtesy of my mobile phone.

This is interesting Craig.
There is a good explanation for your experience.
On some old diesels You have to get them spinning before you fuel them or they wont get sufficient cranking speed & compression to start. It sounds like the same principle is working for you.
At some stage in the start cycle extra fuel is needed as the idle volume may not provide enough to maintain the running of the motor at the start. This fits well with your use of the throttle once it starts to kick.
Given the number of variables in play its not surprising that there are nearly as many starting techniques as there are cars!!

Adam,
Your observation of "hunting" is not that uncommon.
What may be happening is that the idle speed is dropping low enough for some sort of anti stall fueling to be triggered in the IP. That could be set at too higher speed or your idle could be too low. It happens some times on tractors with a similar types of IP. A good IP technician could adjust it. I think its an adjustment inside the back of the IP. There are way too many springs & leavers in there to DIY !!

__________________
Grumpy Old Diesel Owners Club group

I no longer question authority, I annoy authority. More effect, less effort....

1967 230-6 auto parts car. rust bucket.
1980 300D now parts car 800k miles
1984 300D 500k miles
1987 250td 160k miles English import
2001 jeep turbo diesel 130k miles
1998 jeep tdi ~ followed me home. Needs a turbo.
1968 Ford F750 truck. 6-354 diesel conversion.
Other toys ~J.D.,Cat & GM ~ mainly earth moving

My experience is similar to Craig's. At very cold temperatures, 10f and below, adding throttle makes it more difficult to start. I've found that it's easier to let it fire a few times with no throttle then slowly add fuel. Both of us live above 5000' which might make a difference.

__________________
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

0*F this morning,car outside unplugged, turn ed key until gp light was out and car fired like it was 70* out. Those 602 motors sure start nice in the cold.

I'll be curious how my new engine likes to start in the cold. I'm on my way to go pick up the car.

No problems this morning. one glow and it started like normal. I only plugged it in for 50 minutes. I will try it without the heater tomorrow. I think the Kero made a big diference. I am going to ohm the glow plugs when I can get it back in the barn. What reading is acceptable?

The Ohm test is not reliable.

0.7 is what a NEW glow plug reads.
0.8 is IMO marginal.
Any other reading = replace them.


Reading material on the issue.

Trusting an OHM test is a common diagnostic error on glow plugs.
The glow plug is a HIGH temperature heating element = the element can (and does) frequently read OK on an OHM test but is bad/shorted.
The critical factor is electrode resistance at full operating temperature, testing at low ambient is not valid.

Heating to a minimum temperature of 850°C is critical for diesel engine start-up.
Glow plugs run 1000° - 1300°C = up to "2372° Fahrenheit" optimal temperature range.
This is why many members choose to remove the glow plugs, put them in a vice, and manual glow them (often finding bad units that OHM good).

The older Mercedes Benz diesels (pre CDI) have a Pre-combustion Chamber that houses the glow plugs.
Carbon build up on glow plug electrodes acts as an insulating blanket, reducing durability life and making the glow plugs ineffective.
Every time the glow plugs on engines equipped with a pre-combustion chamber are replaced, it should be reamed out to remove any carbon build up.

http://www.wellmanautomotive.com/glowplugs.php

http://www.ngkspark.com.au/glowplug_info.php#

http://www.ngk-dpower.com/en/technik/keramik-gluehkerzen/


Excellent study material.

Glow plugs link thread All diesel models
http://www.peachparts.com/shopforum/diesel-discussion/137732-glow-plugs-link-thread.html#post1019018

Starter health is important to your diesel!!!
http://www.peachparts.com/shopforum/diesel-discussion/107318-starter-health-important-your-diesel.html#post739798

Cold weather starting links
http://www.peachparts.com/shopforum/diesel-discussion/137674-cold-weather-starting-links.html#post1018529



Have a great day.

__________________
ASE Master Mechanic
asemastermechanic@juno.com

Prototype R&D/testing:
Thermal & Aerodynamic System Engineering (TASE) Senior vehicle instrumentation technician.
Noise Vibration and Harshness (NVH).
Dynamometer.
Heat exchanger durability.
HV-A/C Climate Control.
Vehicle build.
Fleet Durability
Technical Quality Auditor.
Automotive Technical Writer

1985 300SD
1983 300D
1984 190D
2003 Volvo V70
2002 Honda Civic

https://www.boldegoist.com/

This is a great thread....for someone who lives in Northern Minnesota and brought her 240D from Cali.

Thanks guys!

Deanna

__________________
1976 300D 217k...an old car needin some love. (GONE OFF TO RUSTY CAR HEAVEN)

1982 240D probably something like 190,000 miles...was Old Yeller, but I changed the name to Buttercup

I discovered taht on my car, when the glow light goes out the glows keep glowing for at least 30 seconds (can't remember the actual time) - probably the same for all the old diesels.
YOu can check this by turning on interior light. when the glow circuit switches off the light will glow slightly brighter, and you might hear the relay click also - definitley if you open the hood.

EDIT: jsut read the whole thread and discovered the above is not such rare words of wisdom after all!

__________________
1983 300SD with bad undercarriage rust, with old greasecar 2-tank conversion. About 200K miles, just an adolescent but with premature bone disease.

I think i have my procedure down, it started with no trouble and no lower rad hose heater. I think it was about 8deg. this morning. I think with all the work to remove the glow plugs i will put new gp's in and check the old gp's and keep the good ones. Where can i get a gp reamer? wasn't there a fella on here who was making them?