To drive or not to drive - E300 running rough and smokey! - PeachParts Mercedes-Benz Forum

Bcollia · #1 03-09-2009, 10:16 PM

I must say that I feel bad about my absence here as of late. It seems that the Michigan cold is not only keeping me away from working on my babies, but also keeping me away from my favorite place on the internet.

Regardless the ole E300 has been getting my through the winter, along with the wife's Lumina on really bad days, until a couple days ago. I put the key in and waited for the glow plug light to turn off, but it never came on!! So I have it a few seconds and started her up. I saw "Check Engine Electronics" on the gauge cluster and she was running like crap. Almost like a gasoline car would if it were missing. I searched the forum and googled and came across a few posts that said to check the battery charge, which I did and it was fine.

My question is, should I drive it to have the code read or get it trailered? I'd like to save as much money as I can (so I have more for the W111's). I called my service guy at the dealership and he said that Autozone may even be able to read the code and get me started in the right direction. I called them and sure enough they can. I just do not want to cause more damage. The fact that the glow plug light never comes on is a clue that they most likely need to be changed.

Any help is appreciated, I miss driving this car!

Thanks guys,
Bryan

project84300sd · #2 03-09-2009, 10:19 PM

its probably running rough because the glowplugs arent working.... does it smooth out as the car warms up?

TMAllison · #3 03-09-2009, 10:36 PM

More than likely it is PO380 which pops whenever its started on cold GP's. I'd guess the relay is suspect not knowing more.

Go to dieselgiant.com and follow the GP tutorial thereon for the W123; you'll need a mutlimeter. The relay is a tad different but the principals remain the same.

Report back on the code or the GP resistance and you'll get more help.

Bcollia · #4 03-12-2009, 05:14 PM

Sure enough it was the glow plug relay. Just left a message for Phil to try and get my hands on a new one. I was hoping to get it today so I may just see if the dealer has one in stock. Thanks again for the help guys!

Anyone know what the part number for that beast is?

Bcollia · #5 03-14-2009, 02:33 PM

Phil is such a life saver! After founding out that the relay was $180 he suggested that I look at the fuse in/near the relay. I spent 5 minutes looking for it to no avail. I read previous posts to follow the wire from the number 5 glow plug, but I believe this may only be true on older models.

Off to the garage!

KarTek · #6 03-14-2009, 03:32 PM

So, all 6 GP's test out OK? Next thing I'd do is turn on the key and quickly, during the time the GP's are activated, go out and check for voltage on all 6 leads.

Fuses are inside the relay. You have to "cut" the case open with a knife by scraping out the sealant on the bottom and prying the case open.

This is the relay with the sealant scraped away:

Here, you can see the "fuses" - the metal strips. They should all be intact:

You might also want to visit the larger electrical connectors with a soldering iron and fresh solder. They were cracked on my relay causing intermittent malfunction.

Bcollia · #7 03-14-2009, 05:56 PM

Haven't checked the leads, put it on an OBD2 scanner and it was throwing the glow plug relay error code. I looked at the "box" attached to the wheel well, part number 0155453032, which looks different than the one you posted. I opened mine up only to find that it looks as though the capacitors leaked. Notice the gob of white toothpaste looking stuff coming out of them. I had to replace the caps the ECU in my VR4 recently, can I do that with this as well? If not I will be giving Phil a call on Monday to get a new one coming.

Sbean · #8 03-14-2009, 06:07 PM

The white stuff looks to me as if it were placed there and spread around the base of the capacitors. Could it be some kind of potting compound or something like that? Is it soft and pasty or rubbery like silicone RTV?
Great pics!!

Bcollia · #9 03-15-2009, 05:36 PM

It is a somewhat gummy substance. Just had a computer power supply go bad and similar stuff had come out of the capacitors. Those caps were discolored though, these are not.

Didn't want to have to spend almost $200 on the ole girl right now, but you gotta do what you gotta do. I am also going to stop by Frank's here in town and see if he wouldn't happen to have one.

Here's a shot of the outside of my relay.

Thanks for the compliment on the photo. My soon to be wife has a nice Canon Rebel xti for her business: http://www.daftstudios.com

KarTek · #10 03-15-2009, 07:24 PM

It looks like they changed the design of the relay between '96 and '98. I believe the "goo" is intended to keep the heavier components secured so they don't vibrate and fatigue the connections and solder.

I would take a very close look at the solder connections on the relay and verify that none are cracked.

Bcollia · #11 03-16-2009, 09:37 AM

Thanks Evan, Could it be something else that is causing the OBD2 to throw the relay error code? I am going to follow this tutorial to test the wiring to/from the relay when I get home to do some final testing before spending the coin on a new one.

http://www.dieselgiant.com/glowplugrepair.htm

KarTek · #12 03-16-2009, 12:48 PM

If some of the solder joints on the circuit board are cracked, that will certainly cause at least an intermittent code due to poor connections.

Bcollia · #13 03-16-2009, 12:55 PM

All of the solder joints appear to be intact. With all of the time I have spent troubleshooting this, it might have been better to just buy a new one...... Money is money though and I would rather be able to spend it on the W111!

Bcollia · #14 03-19-2009, 09:43 PM

Well I ended up completing the dieselgiant guide and it ended up being the #6 glow plug. A new Bosch one will be here tomorrow and I am going to try and replace it without having to take off the intake. Should be fun. Any tips or tricks?

Right now I am stuck driving the wife's car because the 81 is having air cleaner trouble, but that's a whole nother thread!