100K mile glow plugs? - Page 2 - PeachParts Mercedes-Benz Forum

funola · #16 05-20-2009, 10:26 AM

Quote:

Originally Posted by Diesel911

....
I nticed when I hooked up a single Glow Plug to an automotive Amp Meter and connected it to a Battery I noticed it pegged the Meter at 60 amps for a second or 2 and as it got hot the amps went down to aroubnd 16.
So when the GP was cold it pulled high amps=high resistance, hot GP= Low amps and Low resistance.
....

You probably did not mean what you wrote but it is incorrect. Should be:
High amps = low resistance,
hot GP= low amps and high resistance.

My theory of carbon encased glow plugs having a shorter life is that the carbon insulates the glow plug and the glow plug gets much hotter than if it were not encrusted in carbon, thus shortening its useful life. I have no proof, just a theory and I'm open to other theories.

Diesel911 · #17 05-20-2009, 11:29 AM

Quote:

Originally Posted by funola

You probably did not mean what you wrote but it is incorrect. Should be:
High amps = low resistance,
hot GP= low amps and high resistance.

My theory of carbon encased glow plugs having a shorter life is that the carbon insulates the glow plug and the glow plug gets much hotter than if it were not encrusted in carbon, thus shortening its useful life. I have no proof, just a theory and I'm open to other theories.

Actually, I could just be wrong; I am not so swift on the finer points of Electrical stuff.
If the plug pulls higher amps until it is hot a Plug encrusted in Carbon is conducting heat through the Carbon into the Cylinder head would maintain a Higher Amperage due to the Plug tip being cooler over a longer period. Maybe the extended high Amperage is what damages them.

sixto · #18 05-20-2009, 01:15 PM

The glow plug theory doesn't address the propensity for the #1 rod to bend.

Sixto
87 300D

compress ignite · #19 05-20-2009, 03:37 PM

No, But the fact that MB made available (for a short time) "Improved" Stronger
Thicker[in some areas] Rods does.

Jeremy5848 · #20 05-20-2009, 03:48 PM

I have never added up all of the service records but estimate that our '96 E300D is on its 3rd set of glow plugs in 260,000 miles. I personally have replaced #2 and #3 once each. I would think that the number of starting cycles would be the biggest cause of failure; too bad there isn't a counter in the system somewhere.

Edit: I went through my records. Assuming they are complete, in 260,000 miles,

#1 (frontmost) glowplug has been replaced 1X (at 205,000 miles)
#2 3X
#3 3X
#4 2X
#5 2X
#6 2X

Statistics:
Number of glowplugs used: original 6 from the factory plus 13 replacements in 260,000 miles
Minimum miles to failure: 45,948
Maximum miles to failure: 205,548
Average miles to failure: 102,151
Median miles (middle of distribution): 80,417

Comment: at 205,548 miles all six glowplugs were replaced although only one was bad (unknown which one). So the average should be higher.

Jeremy

TMAllison · #21 05-20-2009, 04:19 PM

Quote:

Originally Posted by Jeremy5848

too bad there isn't a counter in the system somewhere.

Jeremy

When DAS stops working and you need a complete ignition system and key replacement you'll know it hit 200k turns of the key......

Jeremy5848 · #22 05-20-2009, 04:39 PM

Quote:

Originally Posted by TMAllison

When DAS stops working and you need a complete ignition system and key replacement you'll know it hit 200k turns of the key......

Not sure was DAS is,Terry, perhaps not in the 1996 model year?

TMAllison · #23 05-20-2009, 05:46 PM

Drive Authorization System - The seurity features varied through the years (yours is simpler than later versions) although to my knowledge all were designed to be replaced after 200k initiations. Requires new door locks too if I remember correctly.

Jeremy5848 · #24 05-20-2009, 07:27 PM

Quote:

Originally Posted by TMAllison

Drive Authorization System - The seurity features varied through the years (yours is simpler than later versions) although to my knowledge all were designed to be replaced after 200k initiations. Requires new door locks too if I remember correctly.

AFAIK, 1996 model year does not have DAS, at least I hope not. Among other things, DAS cars have an electronic ignition switch, right? The 1996 model-year got a simple mechanical switch. I've had mine completely apart; all it is is a fancy rotary switch with no electronics at all.

Jeremy

TMAllison · #25 05-21-2009, 10:08 AM

You got it, or a variant to my knowledge. Your key has a chip in the key fob too right. You can't bypass your ign switch and hot wire it right?

Jeremy5848 · #26 05-21-2009, 11:49 AM

Quote:

Originally Posted by TMAllison

You got it, or a variant to my knowledge. Your key has a chip in the key fob too right. You can't bypass your ign switch and hot wire it right?

The only chip is in the "switchblade" key fob, which is infrared and is used to lock the car and activate the alarm. We also have a plain metal key like the older cars and it works just fine to unlock the doors and start the car. It doesn't have a chip in it and there's nothing under the dash that a chip would talk to anyway. I've never tried to hot-wire the '96 so I can't comment on that.

I know that there's a big computer module that has to be powered up or it won't let the IP deliver fuel but if I could get at the wires that go to the ignition switch and crossed the right ones, yes, I think I could start and drive the car if I broke the steering lock.

Jeremy5848 · #27 05-21-2009, 11:59 PM

There's a DTC in the FSM (DVD version) for the W210 series. It states that Mercedes started using DAS in the 1996 model year but that a limited number were produced w/o DAS. These few, the DTC goes on to say, can be told by SA code 38 in the datacard. And, as it happens, our '96 has SA code 38, which is described as "Power supply RCL control unit for immobilizer." This may be because we have an early '96--the delivery date is 10-26-1995 and the VIN is 005422.

Jeremy

TMAllison · #28 05-22-2009, 12:45 AM

Quote:

Originally Posted by Jeremy5848

There's a DTC in the FSM (DVD version) for the W210 series. It states that Mercedes started using DAS in the 1996 model year but that a limited number were produced w/o DAS.
Jeremy

Well, I didn't know that. I guess YOU can turn the key w/o regard. Although, turning it 200k times is a considerable amount. At 1 mile per start is 200K miles, at 10 per is 2mil miles, so doubt anyone will ever actually reach the end of its programmed life. Wonder if SDS can tell you how far along in the process one is at?