“No-Start” Something Other Than Glow Plug-Related? - PeachParts Mercedes-Benz Forum

wcmartin75 · #1 07-10-2010, 01:54 PM

1982 300 TD (Turbodiesel Wagon)

Based upon the information reported in my previous post here (yesterday or the day before) entitled, “Blowing 80A Strip Fuse in Diesel Glow Plug Relay” and the kind replies to it, for which I am grateful, I have all but concluded that my problem is in the Glow Plug circuit. I have ordered out the necessary parts, including a Reamer, and will report back on the results of my repair.

However, I am haunted by the prospects that the Glow Plug circuit, while perhaps contributing to the problem, may not be the root of the problem causing my “No Start” condition. For those of you who are more gifted diagnosticians than I, please consider the following events that happened moments before the No Start condition presented itself:

1. I had been out running errands and the wagon was at normal operating temperature when I pulled into my driveway and shut her down.

2. Moments later (she was still at operating temp.) when I attempted to restart, I heard a “Pop” (like a firecracker!) soon after I turned the ignition and she began to crank. However, the Pop did not prevent her from catching and firing up.

3. I drove two blocks to the Library and shut her down.

4. A half hour or so later, when I came out of the Library, she would not restart. The engine just cranked, and cranked. I noticed I had no lit Glow Plug lamp in the Instrument Cluster. When I pulled the cover off the Glow Plug Relay, the 80 A Strip Fuse had burned through.

5. What bothers me is that after all that cranking, I could not smell any Diesel fumes under the hood. After all that cranking, wouldn’t the smell of Diesel be pretty strong under the hood? To make sure she was getting fuel, I loosened the Fuel Union Bolt (on top of the Main Canister Fuel Filter Housing) and hand-pumped the Primer Pump to make sure fuel trickled out around the top of the bolt. Is this the best way to make sure she is getting fuel?

6. I guess the reason why I am suspecting fuel supply is that it hurts my feelings that my beloved wagon, I call her “Leigh”, would not start-up without the Glow Plugs at all, given the fact that it is 85 degreed F. here in Texas (although, in all honesty, my valves are ready for adjustment!).

6. Was that “Pop” the sound of the Strip Fuse burning through? What else might it have been? Could it have been anything fuel supply related?

Any thoughts you have would be greatly appreciated.

-Bill

leathermang · #2 07-10-2010, 02:39 PM

Please go to the user control and put your location in the upper right of your posts.. it makes a difference on starting problem answers and AC answers...

Why do you feel that diesel fumes should be in the engine compartment... at the tail pipe I can see... but in the engine compartment... ?

It is not my opinion that that is the correct place to check for fuel delivery... I think loosening the line at the injector is the correct place.. and that also allows any air which might be in the lines causing vapor lock to be expelled.. I have to do this on my tractor to get it to restart if I run out of fuel in the field... ( 1978 with no fuel gauge )

Start at your negative battery terminal and take apart and clean each and every wiring junction... burned fuses can and are often caused by too much resistance in the ground circuit side of electrical stuff...

Adjust your valves immediately. ( which will afford you the chance to look for something like a chain rail guide,etc broken)

That pop might have been something like the timing chain... but hope for the fuse burning in the mean time...

and you are correct that it should have started even without the glow plugs working...

Rick Miley · #3 07-10-2010, 04:01 PM

I'm going to have to disagree with Greg about the engine being able to start without the glow plugs. My 82 starts within 1 second with the plugs hot. Without them, you could crank all day in the Florida sunshine and get absolutely nothing. Even my 99, which is far newer and fresher than your car, needs the glow plugs to start.

I've seen a number of people chase after no start problems with these cars and screw up a bunch of stuff that wasn't screwed up to begin with. So my advice is to not mess with anything until you've repaired the glow system. You're already 100% sure that there is a problem there - the fuse is burned through. So fix that before you start chasing.

barry123400 · #4 07-10-2010, 04:39 PM

Some diesel engines demand some glow plug activity to fire off. They otherwise run normally as far as I can tell. Had a couple of them myself over the years.

The glow requirement was so small with those engines hot I wondered if there was even time for them to glow. Also if the glow circuit went out they would not start when hot.

On the otherhand I have 123 engines that sit all winter. I might forget to allow for the glow cycle on the first one I start. Three or four revolutions at 60 plus degrees and they are runing. Suprises me as well.

leathermang · #5 07-10-2010, 05:16 PM

Ok.. certainly it makes sense to address the glow plug problem since it is already known to exist... or at least the burned fuse and what caused that..
My gut level feelings are still that at 85 F with normal battery,starter speed that one of our engines ... if the compression is half way intact... with 21.5 to one compression ratio... ought to start. But I have no proof of that...

Brian Carlton · #6 07-11-2010, 11:31 AM

Quote:

Originally Posted by leathermang

My gut level feelings are still that at 85 F with normal battery,starter speed that one of our engines ... if the compression is half way intact... with 21.5 to one compression ratio... ought to start. But I have no proof of that...

It appears that the no-start condition was present after a one-half hour soak. This condition is dissimilar from a cold start at 85°F. I'd definitely conclude that a 617 should start without plugs in the former..........the latter is inconclusive and depends on engine condition. Some will start..........some will not.

Note that the 603 is especially sensitive to functioning glow plugs. This engine will not cold start without them...........even at 90° ambients.

leathermang · #7 07-11-2010, 11:44 AM

But on a 617.952 not overheated then shut off.. just the normal ' heat soak ' due to the active cooling of the radiator not being available... that should increase the chance that the engine should start since it means there is no chance the cylinder walls are cold .. impeding the heating of the air by fast compression...
So I still do not understand why it would not start... even without glow plugs working... Unless that pop had something to do with timing or fuel delivery to the injection pump...by an electric fuel pump...

Brian Carlton · #8 07-11-2010, 11:53 AM

Quote:

Originally Posted by leathermang

But on a 617.952 not overheated then shut off.. just the normal ' heat soak ' due to the active cooling of the radiator not being available... that should increase the chance that the engine should start since it means there is no chance the cylinder walls are cold .. impeding the heating of the air by fast compression...
So I still do not understand why it would not start... even without glow plugs working... Unless that pop had something to do with timing or fuel delivery to the injection pump...by an electric fuel pump...

Agreed..........the point is that it should start without glow plugs after a one-half hour soak...........but might not start after an overnight soak..........independent of ambient temp.

bobodaclown · #9 07-11-2010, 12:41 PM

Just covering the basics.. Fuel, Air, Ignition source. You've got the first two covered. If it didn't start the first time. I'd think fuel might be the problem. I'd check your you wiring to the glow plugs and ohm out each plug. You can do it in place or though the wiring. Sounds like one of the glow plugs has an internal short.

Check this link: http://www.dieselgiant.com/glowplugrepair.htm

The fuse melting might have been the pop. I don't know the compression values on you engine or mileage but it might be a little worn and is needing the glow plugs to get things started.

DISCLAIMER!!!
Before ya'll jump on me on the ignition source I know that a diesel engine uses compression for the ignition source. The glow plugs assist during initial start up. http://en.wikipedia.org/wiki/Glowplug

But an engine of unknown compression/condition you need to assume the glow plugs will be required to get it to start.

BoiseBenz · #10 07-11-2010, 06:43 PM

Quote:

Originally Posted by Brian Carlton

It appears that the no-start condition was present after a one-half hour soak. This condition is dissimilar from a cold start at 85°F. I'd definitely conclude that a 617 should start without plugs in the former..........the latter is inconclusive and depends on engine condition. Some will start..........some will not.

Note that the 603 is especially sensitive to functioning glow plugs. This engine will not cold start without them...........even at 90° ambients.

Our cars have never been plugged in. Both run B100 unless its below 10 dF. We are at 2900 feet, which reduces effective compression.

The 617a will start at 50 dF in four seconds sans plugs. The 603a will start at 35 in three. WITH plugs either will start on the third compression cylinder regardless of ambient. The 617a hot starts instantly for about 90 minutes. The 603a hot starts on the ninth cylinder, even if you shut it down and INSTANTLY restart.

The "junker" 617a will NOT start without plugs.

Something is wrong with the car in question. Are you certain the starter didn't suddenly poop out?

wcmartin75 · #11 07-12-2010, 11:13 AM

Thanks for all the great replys.

Leathermang, I don't think the "Pop" was timing chain related. Remember, I said the engine caught and ran after the sound of the Pop. If the Pop had been the timing chain, I don't think the engine would have fired up after the Pop and let me drive to the library, where she would not restart.

As to those comments that relate to fuel starvation, I will loosen the connections at the individual injectors and see if I have supply there. What a coincidence that would be, though, huh?. That a fuel-related issue would crop up just when, for the first time, I think, I have a failure of the Glow Plug light to light up in the instrument cluster!

Thanks again, I appreciate all the good input.

barry123400 · #12 07-12-2010, 11:54 AM

Releasing an injector line nut is okay. Better in my opinion is to remove and submerge the return line from the injection pump in a jar of fuel. Bubbles should be minimal and the height of fuel should gain in the jar with cranking. Use a small jar or container so the cross section of it is small enough you can see the level rising.

kerry · #13 07-12-2010, 12:43 PM

I would spend no time speculating and worrying about any additional problems until the glow plugs are functioning. If it fails to start once the glow plugs are functioning, then it would be worth pursuing other possible causes. In the meantime, just take a Prozac and wait for the glow parts to arrive. If that's not possible, just jump 12 volts to the plugs and see if it starts. If it does, it will save you the cost of the Prozac.

vstech · #14 07-12-2010, 12:49 PM

yeah, we ought to have a cheater that has the female prongs to fit the glow harness for testing of the glows/ bypassing the relay. a simple #10 wire jumpered into all the sockets might do it...

vstech · #15 07-12-2010, 12:51 PM

Quote:

Originally Posted by BoiseBenz

The 603a hot starts on the ninth cylinder, even if you shut it down and INSTANTLY restart.

wow, you have a BIG 603 BC!!!