I knew this day would come - glow plugs on the Benz

"RamblinRover Luxury-Yacht" (ramblininexile)
12/16/2014 at 10:37 • Filed to: None

What I didn't expect was that apparently anything wrong with the system may cause it not to function... at all. This includes such things as just a single plug out. I found this out yesterday trying to leave work...

I don't know with certainty it *is* just a plug out, because (shockingly) it wouldn't start without the glows. It could be a failed relay - which would suck. However, it seems to be most commonly the plugs themselves. The ones under the intake crossover pipe.

DISCUSSION (36)

Funktheduck > RamblinRover Luxury-Yacht
12/16/2014 at 10:45

Don't you just love it when you have to disassemble half the car to do a relatively minor task?

Agrajag > RamblinRover Luxury-Yacht
12/16/2014 at 10:45

Is this the one with the manual you're trying to get rid of?

/stilltrying

RamblinRover Luxury-Yacht > Agrajag
12/16/2014 at 10:46

This would be the W124 300D auto that I drive. Very good try, though.

Twingo Tamer - About to descend into project car hell. > RamblinRover Luxury-Yacht
12/16/2014 at 10:47

Whoever had my car before me must've had issues because my car has 4 shiny new glow plugs. Hopefully that puts me in the clear for the next few years.

CB > Funktheduck
12/16/2014 at 10:48

And everyone with a Volkswagen nods in agreement.

Arch Duke Maxyenko, Shit Talk Extraordinaire > RamblinRover Luxury-Yacht
12/16/2014 at 10:48

Should have bought a gas engine

JR1 > RamblinRover Luxury-Yacht
12/16/2014 at 10:48

It is time:

Kinja'd!!!

RamblinRover Luxury-Yacht > Twingo Tamer - About to descend into project car hell.
12/16/2014 at 10:53

Mine have probably not been changed in over 150,000 miles, so it's not a shock, just irritating that apparently the whole system shuts down.

RamblinRover Luxury-Yacht > Arch Duke Maxyenko, Shit Talk Extraordinaire
12/16/2014 at 10:54

Kinja'd!!!

RamblinRover Luxury-Yacht > JR1
12/16/2014 at 10:56

It's always time to push a 2CV in the drink, because lulz.

Chris Clarke > RamblinRover Luxury-Yacht
12/16/2014 at 10:58

w124 should have pencil style plugs wired in parallel and the remaining should still operate if one happens to go bad.

Twingo Tamer - About to descend into project car hell. > RamblinRover Luxury-Yacht
12/16/2014 at 11:02

It is strange it shuts the whole system down. My grandad had one go on his Mondeo and it still ran, although very badly.

RamblinRover Luxury-Yacht > Chris Clarke
12/16/2014 at 11:03

You'd think that, but you'd be wrong. The glow control relay is no simple relay - it detects defects in overall resistance and sometimes decides for the safety of the system not to operate them. Shorts are the easiest way for it to trip into that mode, but apparently ordinary burned out/open plugs can do so as well. I also don't know it's *not* the relay, the power to the relay (though fuse 7 *looks* fine), nor the ground to the relay, but plugs are first. The relay *is* a suspect, being as it is on a 400,000 mile vehicle... that being said, the plugs apparently do cause this often enough that they need to be checked.

RamblinRover Luxury-Yacht > Twingo Tamer - About to descend into project car hell.
12/16/2014 at 11:04

*That* is the typical way for a system to operate, hence my disgust. Apparently, however, the system can disable itself if plugs are dead - quite unlike the typical.

Chris Clarke > RamblinRover Luxury-Yacht
12/16/2014 at 11:06

The more you know. Very interesting. Plugs are cheap and easy on a relative scale. Always a good place to start. Do you have an ohm meter? Pretty easy to check resistance of a shorted plug.

Grindintosecond > RamblinRover Luxury-Yacht
12/16/2014 at 11:08

Amazing how it disables the whole system if one doesnt work. I woudl suspect if that didnt happen, the other cylinders would work and eventually once the compression heat rises enought the last cylinder would catch. Of course that would be some wretched vibration until then. A strange system of bulletproof reliability crippling itself horribly with it's not absolutely perfect.

RamblinRover Luxury-Yacht > Chris Clarke
12/16/2014 at 11:09

I do have access to a multimeter, I just haven't been able to check them yet. I'm familiar with the process. Funny thing - even with needing to remove part of the intake manifold, I think it's still an easier job than the plugs on my 1.6 VW diesel that I once changed by flashlight in the snow.

Twingo Tamer - About to descend into project car hell. > RamblinRover Luxury-Yacht
12/16/2014 at 11:10

Maybe Mercedes remembered they're german while designing it and made sure the system was strangely overcomplicated.

Chris Clarke > RamblinRover Luxury-Yacht
12/16/2014 at 11:10

Keep us informed. I'm curious what it turns out to be.

RamblinRover Luxury-Yacht > Grindintosecond
12/16/2014 at 11:12

Apparently the sure sign that it's a dead plug and not something else is that the relay cycles once ("afterglow") after the engine starts as per normal, but having never cycled them for starting. That would be great and all, if it were warm enough out to start the engine without glow plugs. It's not, it's really not.

Grindintosecond > RamblinRover Luxury-Yacht
12/16/2014 at 11:15

Saw a video of some guy and a Kubota diesel tractor. He put his hand over the exhaust stack and cranked away. Trapping the air inside the cycles of compression heated the air enough to roughly start it. concept is sound. all you need now is a guy to plug up your exhaust everywhere you go.

RamblinRover Luxury-Yacht > CB
12/16/2014 at 11:15

If you don't half-disassemble the VW before doing a minor task, you typically suffer for it. Then again, the glow plug job on my Rabbit would have required pulling the injector pump to get reasonable access, and... VW? No. Just no. I'm not going to do that.

RamblinRover Luxury-Yacht > Grindintosecond
12/16/2014 at 11:19

That's quite clever. Of course, what would also be clever would be if I had bothered to get a cord for my block heater before this, so I could heat it up and start it that way. There's a block heater *in the block*, *from factory* that one just needed to have requested a cord from the dealer for to use. Sitting there, waiting. This car was used mostly in GA and SC, so guess what never happened and I've been too lazy to remedy since.

Kinja'd!!!

Hahayoustupidludditeshutupandgohandcrankyourmodeltalready > RamblinRover Luxury-Yacht
12/16/2014 at 11:23

NOOO!

Funktheduck > CB
12/16/2014 at 11:31

You had to remove the intake manifold to replace the plugs in my GS300. You could change plugs one and six with ease. The rest, nope. It was a pretty tight fit for everything in that bay. I

Working on my truck? I sit on the fender if I need to do most things that would require me to otherwise hunch over to save my back. I can almost stand between the engine and fenders there's so much room.

KusabiSensei - Captain of the Toronto Maple Leafs > RamblinRover Luxury-Yacht
12/16/2014 at 12:35

See, and all this time I said the OM603 glow system has a better reputation than the OM606.

Kinja'd!!!

KusabiSensei - Captain of the Toronto Maple Leafs > Chris Clarke
12/16/2014 at 12:36

The later build OM603s are in parallel, and so are the OM606 engines.

His is an early build OM603, so hence it's in series, like the OM617 system.

RamblinRover Luxury-Yacht > KusabiSensei - Captain of the Toronto Maple Leafs
12/16/2014 at 12:37

It's just cranky because I didn't give it its metamucil yesterday and all these people it doesn't recognize keep coming by.

rabidpenguin > RamblinRover Luxury-Yacht
12/16/2014 at 12:38

You can test them using a battery or jump starter. They are easy to pull out if you use a long extension and wobbly sockets for the middle cylinder ones. Ground the outside of the glowplug and attach the positive side to the terminal. The ones that are functioning will glow red within a couple of seconds.

The car must start real nice in cold weather without them working, amirite?

KusabiSensei - Captain of the Toronto Maple Leafs > RamblinRover Luxury-Yacht
12/16/2014 at 12:40

You also didn't give it the nitroglycerin either.

At least it's not the evil OM606 DOHC head which loves to eat teh glowplugz.

RamblinRover Luxury-Yacht > rabidpenguin
12/16/2014 at 12:50

Trust me, I know all that. I'm even familiar with the typical resistance range of Bosch 10mm hex glow plugs. These being where they are, the cross-pipe is coming off for that, I'd say.

Why yes, going from (probably most) plugs working to none suddenly is great for starting, how did you guess? I also should have gotten a cord for the heater plug *long* before now...

RamblinRover Luxury-Yacht > KusabiSensei - Captain of the Toronto Maple Leafs
12/16/2014 at 12:51

I have to say, having owned it for years and years and never changing a single glow plug, I'm not really *shocked* by this development, but even so.

Chris Clarke > KusabiSensei - Captain of the Toronto Maple Leafs
12/16/2014 at 12:52

I'm assuming he could do a parallel conversion like I did with my OM616?

KusabiSensei - Captain of the Toronto Maple Leafs > RamblinRover Luxury-Yacht
12/16/2014 at 12:55

No, but now you burn with anger.

#IllSeeMyselfOut

rabidpenguin > RamblinRover Luxury-Yacht
12/16/2014 at 12:55

NAILED IT!

I have done this job before and you don't NEED to take the cross-pipe off. It doesn't make it easier but you can finagle them out without doing that.

KusabiSensei - Captain of the Toronto Maple Leafs > Chris Clarke
12/16/2014 at 12:58

He probably could get the control system from a later OM603 or an OM606 and go completely parallel.

My OM606 Benz had a glow plug which would phone it in on occasion (only partially), and it would run on 5 cylinders for a few minutes. Instead of doing the plug, I installed the block heater cord and did that.

I really need to go find a W210 or W211 diesel again...