'99 E300 Cold Start Difficulty
 

And so begins the story of my baby's latest problem...... :(

My E300 (OM606.962, W210) has difficulty starting on a cold engine every morning (~45F here in Sac), it doesn't really have a hard time, just that it stumbles a little bit.
Symptoms include rough running for 5-10 seconds and grayish-black smoke, all of which go away after about 10 seconds and then it idles perfectly.

My guess is a blown glow plug or two, which wouldn't warm the prechambers enough in one or more cylinders, causing those cylinders to idle poorly and thus affect overall idle quality. After the prechambers warm up the problem goes away.

Any thoughts?

Time to change the glowplugs!

Remember, do NOT force them out.

I guessed as such, seeing as it's wintertime and they haven't been changed in all of 155,000 mi (!)

My number one fear is the fabled "606 glow plug breaking off in the head" problem.

To find out which ones are bad, can i use the OBDII system or must i remove the intake manifold to test each plug?

That and loose O rings on your fuel lines,particularly the pre-filter.

Know all about it,went thru it all.

If they're original you might as well change them all...you'll just be pulling the intake off again in a few months to change the next one if you don't. The most time consuming part of the job is R&R of the intake...it takes 5 minutes to R&R a plug. My tip is to do it with the engine warm to minimize the chances of breaking one. You can even run the engine with the IM off, though it will throw a CEL with a P0400 code for EGR error if you do, but you can easily reset that with an OBDII scanner once it is all back together. Once you have the old plugs out, ream the holes with the proper tool and put some anti-seize on the new ones and you'll be set for another 8 years.

Alright, I'll probably order parts this week and possibly do the job next weekend.

I have the MB-WIS DVDs and i'm sure i've seen instructions for replacing glow plugs, those'll probably have the part# for the reamer; is there a specific anti-seize i should use?

I figure i can R&R the intake pretty quickly seeing as i've already learned the hard way how to put it back on :D, but i don't think i'll run the engine w/o the manifold (the last time it was off one of those little plastic retainers broke off and fell into a runner, luckily that cylinder's valves were closed!) Ouch that would hurt!

I used a copper based anti-seize on mine. The reamer Samtag sells is $158...I bet the MB one is less. The MB tool number for their tool is 901-0053. You can email Phil at Fastlane and ask him the cost or call your local dealer. I'd use only MB OEM glow plugs too.

http://www.samstagsales.com/mercedes.htm#diesel

Mercedes doesn't even include a reamer in the WIS instructions for replacing glow plugs.
The process is, in a nutshell, remove intake, remove glow plug, install new glow plug, reinstall intake. DUH! :D

There is, however, a special "Glow Plug Repair Set" for "removing broken off glow plugs out of cylinder head as well as thread repair," part#: 611 589 00 99 00.
Includes about 20 various bits, taps, depth stops, thread cutter...."Special Order, Price on Request" from Samstag Sales.

Yes, I have heard that some dealers have them, some people have claimed that they have been able to succesfully drill out broken plugs and retapped the threads while others claim they have had to have the heads pulled so the stubs could be removed at a machine shop. It's all the luck of the draw.

That's why I said I think a good tip is to work on a hot engine, shut it down and as fast as you can remove the intake and start pulling out those GPs. If you're lucky, like me, you'll get them all out without breaking one.

I've heard it is the carbon built up around the tips that causes them to stick in the holes not the threads being seized so the reaming is recommended to prevent that and also open up a hole for the new plugs to work well and last long. The anti-seize is just extra insurance to help the threads from stikcing the next time you have to change them.

The first time my car had the symptoms you are describing, it was air in the lines. The second time it was the glow plugs.

If the starting problem is related to the glow plugs, wouldn't the glowplug light indicate a problem?

Are you sure that air isn't getting into the fuel lines?

Change the GP's certainly
 

However, I am also in agreement that if a GP is bad you will be notified electronically.

One bad glow plug triggered a check engine and glow plug light for me. I'd sure test them all with an ohm meter before tearing into them. Good ones will measure about 0.6 ohms cold. It is possible that you might have a small fuel leak causing your problem. But if it turns out to be a glow plug, then I'd change them all as well as any fuel lines and O rings leaking under the manifold.

BTW, I'm one of the ones who was successful in drilling out a broken glow plug. A search for my user name and glow plug will bring up the details of my experience. There is no question that I'd give it another go should it happen again.

Len
'99 E300TD 97,500 miles

So from what I've gathered I should be seeing a Check Engine light and be able to pull a code if a glow plug is bad....I was wondering, are the electronics in these W210s very reputable? I've had no major problems but once or twice it gave me false low-oil-level readings or ABS failure warnings, etc. I'm just not sure if I should trust the computer to tell me if a plug has failed, just like I wouldn't trust a computer to tell me my oil level is low if the motor has no dipstick (new CDIs, etc.)
It certainly would help not to have to remove the intake to diagnose a blown GP but there isn't a way to tell for certain without removing it.....
:dizzy2:

On the other hand....
 

If it's not glow plugs it might as well be a small air leak into the lines, not that bad because the motor has never failed to start because of this.

(I could see air as a possibility with all the biodiesel i've been running...straight-up B100 for over a year now .. even though I had the lines replaced before I started using it)

Regarding the glowplug light not illuminating being an indicator of bad plugs, I know that at least on the 60x engines it's not quite that simple.

It says in the manual that if the GP light does not come on, that means the #1 GP is bad, or two or more GPs are bad elsewhere. Meaning that if only one GP (#2-6) is bad, your GP light will still come on.

I'm sure this has changed by 99, but this is how it works on my 87. Figured I'd mention it to see if people can confirm that this is correct.