Why Wont you start?? Stuck on side of road - HELP!! - PeachParts Mercedes-Benz Forum

wilburtual · #1 04-09-2012, 01:16 AM

Ok, so I went for a beautiful hike in the Pasadena hills and came back to my 1977 240d and it won't start so here I sit at the side of the road..( posting this from my phone)
Anyhow, it has power, cranks fine, just no signs of fuel burning, no stutters, just cranking.
I was parked uphill so I neutraled a crazy back flip downhill, and am now facing downhill. I have fuel, I put my 5 gal emergency fuelfrom trunk in too...
Primary fuel filter is passing a gush of fuel, so not clogged, secondary filter spits fuel from the top bolt when loosened so I assume not clogged, I loosened the injector lines at the injectors and all 4 spit fuel when cranking... So I assume this means fuel is getting to the injectors, and thus the IP is working... And there are no fuel clogs ..
So why no start???
But, I am not getting and glowplug indicator (which i usually do)when turning the key... But the block feels warm and Ive been cranking a lot formthe past few hours and it seems to have gotten warmer (the block by the GPs)
Luckily I have some tools with me ... Tested voltage when key turned to GP position and get 12v to ground before the flat fuse and get 12v to ground after the fuse. I get 0-1kohm resistance along the GP chain and get an unbroken circuit from the last GP to ground so it seems tue GP circuit is on when turning the keys... But I guess I don't know If the GP are actually glowing... Im in Los angeles so it was hot today and not that cold now and like I said the block feels warm around the GPs....
What else should I try or look for?? Why won't my buddy start??

JamesDean · #2 04-09-2012, 01:56 AM

Verify 12V at the glow plugs on the block, perhaps they are not turning on or have gone bad?

The idiot light nor working properly might indicate something else is wrong internally.

A bad idea probably, but if the GP relay is not working, you could bypass it and run 12V straight into the glow plugs for like 30-40 seconds. If you've got some spare wire with you, something reasonably thick.

You could try to pop-start it going down hill? That might be scary though.

sleepstar · #3 04-09-2012, 02:24 AM

this happened to a friend.. just like you describe, we checked everything like you did and thought it couldn't be a fuel delivery issue, but it ended up being the spin-on filter.

Scout-Ranger · #4 04-09-2012, 02:30 AM

Do you have manual tranny? If you are facing downhill, check there is no traffic on your lane, turn your key to position two, dont crank it just yet. step on the clutch, put the shifter to second gear, release parking brake, get the car rolling and at speed, slowly release clutch and your car might start doing this procedure.

I think your glowplug is the culprit. You can limp back home and sort out the problem there or a repair shop of your choice. Good luck

sleepstar · #5 04-09-2012, 02:34 AM

oh i just see you have a 240.. i think with the amount of miles on your motor, if even 1 glowplug was out, it would be hard to start. also the 77 had the gps wired in a series, if one goes, they all go

kerry · #6 04-09-2012, 09:32 AM

I'm guessing a glow plug problem. You should see the heavy squiggly wires get hot with the key in the glow position. A certain test would be to put your finger on one of the squiggly wires after the plugs have been glowing for about 30 seconds. If the flesh burns, the plugs are working. If not, you've got a bad glowplug which will take out all of them.

Biodiesel300TD · #7 04-09-2012, 11:28 AM

He's in LA, they don't even need GPs down there. It barely even gets chilly down there!

Try unplugging the vac line from the shut-off valve. Sometimes the vac doesn't bleed off like it's supposed to and keeps the IP in shut-off mode. Also make sure your stop lever is jammed to the shut-off position.

Phillytwotank · #8 04-09-2012, 01:29 PM

could be onto something with the series type GP's. The Vac shut off might be something too.

reinventthewheel · #9 04-09-2012, 01:34 PM

Quote:

Try unplugging the vac line from the shut-off valve. Sometimes the vac doesn't bleed off like it's supposed to and keeps the IP in shut-off mode. Also make sure your stop lever is jammed to the shut-off position.

I second this

wilburtual · #10 04-09-2012, 02:46 PM

cool, thanks for all the suggestions, i'm heading back over to the car (had to leave it on side of road and call a friend to rescue me)
Right before i left i tested voltage at the tip of the GP closest to firewall (not sure what # technically that one is) but, the first one to get power.. anyhow, there was 12v there, but when testing the tip of the next in line, no voltage.. so maybe that guy is the problem, also , the curly wires were not getting hot when the key was turned. so i'm gonna grab a couple GPs and head over there.
I'm just surprised that all my cranking and that it wasnt that cold out I could've got it to at least stutter a bit, i never knew GPs being out was a for sure no-start. but then again my other 240 is an 81 and has the other type of GPs so even though a couple were bad when I bough it, it started,,just rough after a lot of cranking.
in the future, is it possible to jump past a bad GP and try to get 3 working etc? I had jumper cables with me last night and was thinking after I got home maybe i coulda tried jumping past the GP by clipping the jumpers to the squiggly wire before and after the bad GP?

If replacing a GP doesnt do it, I'll check try vac line at the shut of valve.or wait, maybe i'll try that first since that doesnt require as much work as replacing GPs..

I'll report back

vstech · #11 04-09-2012, 03:06 PM

jumping one may work, but it will feed higher voltage to the others...

wilburtual · #12 04-09-2012, 03:29 PM

ah, so it appears the older style GPs arent avail at any local parts stores

so I'm gonna have to order one, or more.. but I gotta get the car off the street where it sits, so Im trying to figure a way to get it home while i wait for the GP to arrive. can i jumper past a dead GP? i keep reading different threads where people say you can, some say you can't because each GP wants a lower voltage and relies on the voltage drop of the other plugs and resistance wire... so, if i can jumper a GP where and how do i do it? can i connect a jumper to the resistance wire on each side of the dead GP?

kerry · #13 04-09-2012, 03:37 PM

Yes, a heavy jumper wire bypassing the bad one would work. If there's only one bad one, you could put it in the front most hole, leaving three goods ones in the back, and then ground the one closest to the front to get power thru the back 3. figuring out which one is bad requires testing the continuity thru each one. The test you described didn't prove that the one nearest the firewall was bad. If you take the wires off, look closely at how they are attached and where the insulator goes. They will need to be reinstalled exactly the same way.
You may also have low compression which means it would need the glowplugs to start more than an engine with healthy compression.

reinventthewheel · #14 04-09-2012, 03:47 PM

Quote:

ah, so it appears the older style GPs arent avail at any local parts stores so I'm gonna have to order one, or more..

If you're going to order glow plugs, just upgrade your system. The new pencil plugs are about $16 each plus a few bucks for wiring. Definitely worth the upgrade. You can use the existing relay.

Quote:

but I gotta get the car off the street where it sits, so Im trying to figure a way to get it home while i wait for the GP to arrive.

No AAA? With the economy as it is, lot's of independent folks are doing tows for $50 or so. Check auto services on craigslist.
If it has a block heater, you can plug the block heater in for a few hours and that should do the trick. But I'm guessing there's nowhere to plug it in where it's sitting.

Quote:

You may also have low compression which means it would need the glowplugs to start more than an engine with healthy compression.

I've started cars with good compression without glow plugs, might be a good time to check your compression as half the job (removing the plugs) will already be done.
If it's warm enough out you an engine with good compression will start without

kerry · #15 04-09-2012, 03:53 PM

You'll have to get the 'retrofit pencil plugs', not the standard pencil plugs which replaced the loop plugs in later years.