Cold start - loud knock - bad glow plug - PeachParts Mercedes-Benz Forum

Warren C · #1 01-05-2009, 01:50 AM

1999 E300D

I've had a glow plug problem for a couple of weeks now....light stays on after startup. Also...of more concern...is a very loud knock on a cold start up. it goes away after a short while...and does not occur on a warm start up.

Can this be caused by a bad glow plug ....causing no combustion in that cylinder on cold start up.

It's a really loud knock....quite alarming...but goes away at higher rpms or about 15 seconds of engine running.

Can one bad glow plug cause damage if not fixed right away.??

Warren C.

JimSmith · #2 01-05-2009, 10:04 AM

Yes - a bad glow plug will cause a much less calm start up. Knocking and smoking are pretty much to be expected. I doubt it is a long term concern, but it also can't be good for anything. Check using the electrical connection on the relay at the left side, inner front fender. Pull the plug and check for continuity. Chances are you have more than one gone bad if the knocking and smoking is really dramatic.

If you are a DIY'er read up on it here. Not a difficult job if the glow plugs don't break off.

Jim

TMAllison · #3 01-05-2009, 12:03 PM

X 2

Go to dieselgiant.com for a good write up (for a W123) of how to check the GP's and relay with a multimeter. Our W210 relay is different but the principles remain the same.

DTC's P1365, 67 & 69 are bad GP's at Cyl's 1/2, 3/4, & 5/6 respectively.

Warren C · #4 01-05-2009, 12:17 PM

Thanks guys....I've recently read the DG thread on testing.....will test today. Sure to find some needing replacing. Car has 183K.

Yes I'm a DIYer...although I've been dreading this job....since the manifold has to come off....not to menton all the horror stories of plugs busted off in the head.

What's the best source ....and brand.....for new glow plugs...DieselGiant wants $170/set. Should I order the reamer tool too?

In the Parts catalogue here....there are two types listed.....one called "Duraterm" for $26 each..other one, not named by manuf., is more expensive. Expected to see them by Bosch.

I'll make sure I have a good stock of PB blaster on hand and I'll use a torque wrench. What's the maximum torque I should apply?

Warren C

TMAllison · #5 01-05-2009, 12:40 PM

Beru GP's were OEM. Their head/nut is a little larger than the Bosch plugs. Dont know if that makes them stronger or not but is what I've gone with previously.

You ought to ream the hole. The 606 reamer may be avail for loan here.

Warren C · #6 01-05-2009, 01:53 PM

Quote:

Originally Posted by TMAllison

Beru GP's were OEM. Their head/nut is a little larger than the Bosch plugs. Dont know if that makes them stronger or not but is what I've gone with previously.

You ought to ream the hole. The 606 reamer may be avail for loan here.

Terry,

Does "available for loan here" mean from you? Where you located in N. CA? I live in Mill Valley but have a workshop in Richmond.

Warren

TMAllison · #7 01-05-2009, 02:34 PM

I don't have a reamer. If/when I have to do it next I'll prob use a drill bit of the appropriate size.

IIRC AKLIM has used the brass brushes from a gun cleaning kit.

JimSmith · #8 01-05-2009, 04:04 PM

Warren,

I don't know how aggressively you drive, but I have made it a practice of giving mine a serious "Italian tuneup" before getting into the glow plug removal job. Long hills with lots of load and high rpm, loses lots of black crud in big clouds out the rear. I have been lucky so far and have replaced each plug more than once in about 150k miles.

Never happens in the summer - always a winter event. Just the way Mother Nature works. Good luck and be sure to follow Lightman's intake manifold removal procedure - not a problem and you can actually get good at it.

Jim

Skid Row Joe · #9 01-05-2009, 06:48 PM

Good advice, Terry and Jim. 'preciate the extra tips.

Diesel911 · #10 01-05-2009, 08:14 PM

Besides Reaming how about some Never-Seez type stuff for the threads on the new Glow Plugs.

TMAllison · #11 01-06-2009, 12:41 AM

Quote:

Originally Posted by Diesel911

Besides Reaming how about some Never-Seez type stuff for the threads on the new Glow Plugs.

This 606 issue is kind of like an oil thread. Others will disagree with what I say. Vehemently!

The issue of anti-seize is evenly split 50/50 amongst the techs I respect and have personally polled on this forum concerning the issue.

MB didnt use it OEM and didn't go to it on the CDI's during the next 10 years after the first 606 came out either. They apparenttly didnt feel it necessary?

Mine didnt get it at 110K (the last time they were done) and although they squeaked a bit, thye did come out easy. If/when i have to do it again I'll use Beru's (again) and fore-go the anti-seize.

If I lived in a very cold winter climate rather than where I do, I might decide differently.

FWIW - Beru does make a high temp grease that they recommend; not for the threads, but for the metal shaft of the GP body.

Warren C · #12 01-06-2009, 02:07 AM

Do you guys normally replace all 6 each time...after all the trouble to remove the manifold, etc........or just the failed one(s)
?

Warren C.

TMAllison · #13 01-06-2009, 12:05 PM

"If it aint broke why fix it"; there is risk of one breaking each time it is touched.

The IM comes off in 10-15 minutes after you've done it once. You'll want a new IM gasket and to clean the gunk out of it while its off. May as well get a new EGR seal ring (oring) too.

e300D97 · #14 01-06-2009, 04:03 PM

I dont know if the 606 turbo has them or not, but I got bit when disassembling the IM, one of the wires cracked to the control for the intake flaps. At least on the NA 606 I recommend just replace all while in there, you have to remove the crossover pipe and IM with those damn electro/vacuum flaps

JimSmith · #15 01-06-2009, 10:37 PM

Quote:

Originally Posted by Warren C

Do you guys normally replace all 6 each time...after all the trouble to remove the manifold, etc........or just the failed one(s)
?

Warren C.

I side with the "if it ain't broke don't fix it" philosophy noted by TMAllison. I can get the manifold off in less than half an hour now, so it really is not the impediment I first imagined it to be, and I believe we all have (and know I do) this thread: http://www.peachparts.com/shopforum/showthread.php?t=88574
by Lightman to thank for making the job seem as straightforward as it actually is.

I also use a high temperature anti-seize coating for the threads and the barrel of the glow plug. As already noted I give it a healthy "Italian tuneup" before starting the job in an attempt to burn off and blow out as much built up carbon as I can. I can't say the anti-seize is doing anything in particular, good or bad, but I have not had a stuck plug yet.

As already noted by TMAllison, if the intake manifold has not been off recently (like in the last 100k miles) you will be surprised at how much crud is inside, choking off the air flow. This stuff is really not easy to get out. I cheat and take the manifold to a high pressure car wash and after soaking it in solvent for several hours, I blast it clean with the wand. The local car wash does not endorse this as it makes a big mess. I pressure wash the floor and anything on the walls in the stall to make it so the next client doesn't get that tar like stuff all over his feet. It works though.

Good luck, and be patient. Jim

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