Old Deis,

I'm currently tracking all the superb suggestions I've received from this board and if/when I see the tech, will explain the symptoms and ask how he intends on tackling the problem. If his response matches the information I have and he can justify why he's going to try a particular repair, I'll go along with him. If he gives me some off the wall nebulous answer or starts tap dancing, I'll go to another tech. However, the guy has a good reputation, has been in business 31 years, and is an authorized Bosch repair facility so that initially bodes well for me. We'll see.

However, at this time, will hold off seeing the tech until I run a few bottles of Redline through the engine, do some high RPM trips and try some other suggestions I've received. Already, increasing the glow plug warm-up time has made a major positive difference by a quicker start, no smoking, and leaving me with only a slight miss which is resolved with increasing the RPMs to about 900.


Skip

You're welcome VirginiaDude. I'm going hold off trying the diesel purge until I run through all the potential fixes I've got listed, one at time. Otherwise, if something works, I won't know which fix worked.

By the way, came across an excellent narrative with photos included on how to perform the purge. Suggest you take a look at it.

http://www.mindspring.com/~houlihan/merc/purge.htm

Skip

VirginiaDude,

When you use the purge, would appreciate you letting us know if you obtain any noticeable improvement, decrease in engine miss, etc.

By the way, where do you live in Virginia? I lived in Arlington for 8 years and graduated from Yorktown High School.

Skip

TheVirginiaDude,

Looking forward to hearing how well the purge works.

Worked at a drugstore at Tyson's Corner way back in '67 when the place was just getting off the ground.

Skip:

Your GP relay may be getting tired -- the time the GPs stay on is determined by a temp sensor on the relay, so if it is going bad, they won't stay on long enough. New plugs won't help.

The contacts can also get burned, so you don't have enough current to get the plugs hot.

A new relay isn't that expensive. I'm fairly sure you don't have any other problems.

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

Peter,

The way the engine has responded so dramatically to extending the glow plug warm-up time, I agree with you that a defective GP relay is the number one suspect and carbon/soot clogged prechambers number two.

Thanks!

Skip

When its warm out, I don't use the glow plugs for nearly as long as soon as the light goes out. 280Kmi and no starting smoke in warm weather. Whe its cold, I glow them for 10-15 more seconds to get rid of the smoke. From what I have seen, if you need to glow 10-15 EXTRA in warm weather then something is not right. here is no afterglow in your car. Glow plugs are shut off when the starter engages. If you listen carefully you should be able to hear the glow plug relay shut off if you hold the key long enough. On my car thats 15+ seconds after the light goes out.

__________________
Brian Toscano

In my experience changing out all the glow plugs, the pre-chamber area where the glow plugs are inserted was badly carboned up. I used a glow plug reamer to clean this out in that immediate area, and it got out a bunch of carbon. Removing the old glow plugs required a lot of care because carbon was caked around then.

So that does lend some weight to the carboned-up prechamber theory.

The effect of some smoke and stumbling on cold startup is not worth it to me to pull the pre-chambers out for cleaning. And I have my doubts that Red-Line can clean this stuff out, but its worth a try.

Ken300D

Brian,

Assuming (there I go using that word again ) you didn't want me try this test with the engine running, I turned the ignition key, the glow plug light came on, and then about 5 seconds later, when it went out, I noted the time. The three times I did this test, I heard a distinct solenoid relay "clunking" sound after 27, 28, and 27 seconds respectively. Could this have been the afterglow relay turning off? If so, it sounds like that portion of the relay is functioning properly.

Skip

Ken300D,

When my mechanic (ex now) replaced the glow plugs, he never mentioned if they were carboned up or not so I don't know what condition the pre-chambers were in. But since I haven't driven the car hard since '87 when I had no problem blowing out the carbon as I slowly cruised at a constant 110 mph on the German autobahn's, it wouldn't surprise me if they were clogged up. I say "slowly cruised" because I was passed by over 25% of the drivers.

I've decided to run it hard with a few tanks of Redline Diesel Fuel Catalyst and if I still have the engine miss on a cold start and smoke without giving it the additional 20 seconds glow plug warm-up after the light goes out, I'll have my new mechanic determine the condition of the pre-chambers and glow plug relay.

This pursuit is getting interesting.

Skip

Afterglow is when the glow plugs continue to operate after the engine has been started. In some cars with afterglow, the car will idle real good for 10 seconds, and then it will run rougher. It starts acting rougher then the afterglow timer turns the system off.

Is this a Euro 1987 300D?? If so, cool! US 300D's (and I believe Euros too) did NOT have afterglow. Once the starter was engaged the plugs turned off.

You might also try some Diesel Purge make by LubroMoly. Connecting it directly to the fuel lines in the engine compartment is the BEST way to run this cleaner (diluting it in full or even nearly empty tank is not as effective). I ran TWO cans of the Purge thru my car and it took away rough running at 1100 RPM. It can do amazing things!

__________________
Brian Toscano

Brian, yesterday TheVirginiaDude and I discussed the possible benefits of using Diesel Purge to clean soot and carbon build-up out of the pre-chambers and from what I've gathered from other threads and forums, the general consensus is, unfortunately, mixed.

So, while Diesel Purge is on my list of possible fixes, I'm going to see what effect, if any, the Redline has. If there's no change, I'll likely bite the bullet and take it to a mechanic. After having the glow plugs and injectors replaced already, I doubt that the cost of any further repairs will come close to what I've already sunk into finding this gremlin. Besides, with the miss on a cold engine start when it's 80 degrees outside, I don't even want to consider the trouble it would give me when I take it up to Charlottesville this coming winter when it's in the 20's so it WILL be repaired before I head north on I-95.

I picked up the car from the MB factory in Stuttgart in June of '86 but the bill of sale states it's an '87 300D because the factory rep said it normally takes 6 months to a year for the MB's to reach the U.S. and hit the dealership because the Germans get them first so we have to wait in line. It's not a grey market car and is built to U.S. specifications so I don't believe this is a Euro MB even though I purchased it there.

Skip

Skip:

Get that diesel out on the highway and drive like you are in Germany for a while. A long trip (say, Florida, maybe) at 80 in heavy traffic would be perfect.

Reason is carbon buildup from low load operation. Lots of full throttle short runs will help, too. Get the ricer boys with their sewerpipe japo puny cars to race you at stop lights (but don't get a ticket!).

I'd gladly exchange smoky starts and missing for what mine did this morning -- got in, ran the glowplugs (about 15 sec), hit the key, and got only a "thunk". Dash lights dimmed out. Tried again, same result, so bailed and drove the 280 again (what a gas hog!).

I can turn the engine in the normal direction with the bolts on the power steering pump, so my worst fear (cracked head and hydrolock) wasn't realized, but now I've come to the conclusion I have a bad starter. Dash lights don't dim with the glowplugs, so I don't think the battery is bad -- it's too small, but only a couple years old and it started fine at 0 F this winter. Made, I think, a funny crunching noise just as I turned it in the region of the starter -- hope the ring gear isn't chewed up, it's been noisy for short while when starting.

ANOTHER starter, just put one on the Volvo a couple weeks ago......

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

Peter,

Got a hearty chuckle out of your suggestion to make a high speed run to Florida to rid my engine of carbon chunks because would you believe I live in Jacksonville, Florida? But I definitely got your drift and will use it. As a matter of fact, for the past two days, due to suggestions from you guys, I've started driving like some of these 18 year olds and there's already been a noticeable difference in increased acceleration and it's not polluting the area with black smoke as it was initially when I punch it.

Will use the Redline combined with some testosterone laced driving and see what happens. And if the miss/smoke doesn't disappear, I'll take it to ye old mechanic and see what magic he can render.

Sorry to hear that your starter has gone belly-up. And here I was whining about a balky car? Wish you luck in getting her up and running again.

Skip

Skip:

If you are getting black smoke on takeoff, I'm pretty sure you need an "Italian tuneup". Go beat some ricer boys in their hopped up cars, you will both be the better for it! MB diesels carbon up pretty bad in slow driving, makes them run poorly, start hard, and smoke.

I'm going to double check tomorrow that the crank turns when I turn the power steering pump pulley (it's unlikely it isn't, but hey, it only take a minute or two) and then stop in to see my parts guy in the AM on the way to work. I spend more money there than anywhere else, even with the deal he gives me!

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!