Here We Go! - PeachParts Mercedes-Benz Forum

#1 11-10-2003, 05:05 AM

I warned you all that I would be posting ....So here we go. I have an 83 300D (W/ 175,000 miles) that is an incredible car to cruise with (@100mph+/-). However, getting up to that speed is another story. Sometimes ( and this is what is strange) the car can't get out of its own way..."SPUTTERING, Coughing, and belging out blue/gray smoke until about 2500rpm, and then it clears its throat and is ready to run. I've noticed that when the car is started cold and driven for the first time (any given day) the problem is not so bad, however, if I park and then start it again (warm) it is very bad. So bad, almost don't want to drive it for fear of causing an accident. Recently, 2-weeks ago my glow plugs died ( no light), but the car fires right up, however, problem been with me for 2-years.
I live in the Northeast (New Paltz NY) and last winter I had absolutley no problem starting it up in the mornings (did'nt have to plug in until temps dropped below 15 degree F). At high Rpm's no problems. When the car is at idol no smoke no sputters....purrs like a kitten. A shop by me said could be transmission problem i.e. linkage, another shop said could be injection pump ( bad or out of sink).
Oh-ya currently city=25mpg...highway=29mpg.
Any insight will be greatly appreciated.
Thank You
Matthew

diesel don · #2 11-10-2003, 07:51 AM

A couple of suggestions were given to me when I acquired my first 300TD (wagon). At that time it would barely (and i mean barely) make it up our hill.

Disable EGR
Tighten Throttle Linkage
Clean out bolt/bango fitting at the rear of the intake manifold. Same for switchover valve
Fuel Filters
Valve adjustment
Lubro Moly Diesel Purge
Bypass overboost Protection relay
Adjust wastegate settings, but only after measuring current boost pressures
Tune the ALDA fuel/air settings. Be cautious...adjustment springs break

Of course, these all sounded overwhelming but I found most of them to be easy. As I worked my way through them, the car began to jump.

As I've now acquired 8 of these diesels, I always do the following order because of its ease and results:

1. Clean out bango bolt at the rear of the intake manifold. Just unscrew it (two pieces to the bolt). You might have to break the clear plastic that is attached to it (no problem, just splice with rubber). Soak it in some cleaning solvent until the hollow parts are clean.
2. Adjust valves
3. Fuel filters
4. Adjust the ALDA (this almost always makes a difference)

Don

leathermang · #3 11-10-2003, 08:25 AM

The good news is that many of the descriptions of your car's performance indicate you have a car in very good condition. Things like it starting fine without block heater down to 15 degrees.... and the mileage is wonderful and right on the mark....
It is important to distinguish between the ' light' and the actual glowplug operation... and it sounds like only the light is out....
All of Don's suggestions are very prudent and should be done to any diesel just on principle anyway...

R Leo · #4 11-10-2003, 09:45 AM

Quote:

All of Don's suggestions are very prudent and should be done to any diesel just on principle anyway...

Excepting this one:
Bypass overboost Protection relay

IMHO, I'd check the overboost valve/relay and make sure that the tubing wsn't plugged or leaking. If you do decide to operate 'sans protection', make sure you have a boost gauge where you can see it during normal operation.

leathermang · #5 11-10-2003, 10:50 AM

Those sorts of misses happen when 240 guys review turbo threads....I agree with RLeo... CHECK the bypass relay to make sure it is working....

diesel don · #6 11-10-2003, 11:32 AM

I agree with the two prior statements. It should be noted that such advice came to me only. I have not attempted the overboost deal. I don't even understand it.

Regarding the one thru four post that I made, that I can stand behind.

Thanks

Don

#7 11-10-2003, 08:47 PM

Ok...You all are over my head. What is the Alda, what is boost, where is the relay? I'm a biologist not a mechanic, however, with proper guidence I can manage to get through just about anything. (I managed to keep my 1995 Chevy blazer on the road, and she has 185, 000 miles all orginal, bought her with 8 miles).
I guess I should start with some literature to bone up on the lingo. As for the glow plug issue, the car does have trouble starting especially first thing in the morning, however, when warmed up will fire right up...so I am planning on changing out the glow plugs (only about $60 if I'm not mistaken).
As for the other things should I attempt them on my own or have a mechanic look into them. I have a guy I believe is reliable, not a diesel head (an Audi Guy) but he is mechanically sound. Or does anyone know of a good shop in the Hudson valley (NY) area.
The other thing I omitted from the first posting was that I'm having trouble with the vacume system....locks won't always work, tach jumps erratically, sometime car won't shut down (good thing for the KILL button). However this is when the car sits for a while and is only driven around town, when I run her on the highway all vacume problems go away.
Agian thanks for the info...You all ROCK!!!
Matthew

KPMB82 · #8 11-10-2003, 10:01 PM

OK I'm new here too. I'll try to help out. I'm sure I'll be corrected if I'm wrong. What is the ALDA? The ALDA is the mushroom shaped device on top of the Injector Pump. it adjusts the amount of fuel the pump injects as the Boost pressure rises. What is Boost? Boost is what you get from your Turbocharger, the turbo forces air into the intake manifold and actually builds up a positive pressure measured in Bar, or for mormal people pounds per sqare inch (PSI). The overboost protection relay is mounted on the fire wall on the drivers side just to the right of the power brake accumulator. First let's check the Boost sense lines. Start at the very back of the intake manifold, Find the bolt and "banjo fitting" with the clear/whitish plastic line. The line runs to the overboost prot. relay on the firewall. Another clear/whiteish plastic line runs from the overboost prot. relay to the ALDA. Got it? Ok disconnect the bolt/banjo fitting, there should be a washer on each side of the banjo fitting don't lose them. Now remove the line from the over boost prot. relay there is probably a clamp on the rubber connector to the relay. Clean the removed bolt and line with a piece of wire and some brake cleaner. Put it back together, do not over tighten the banjo fitting bolt, that's bad. Now remove and clean the line from the relay to the ALDA, same deal. You should clean out the holes into the relay also just with the cleaner, not the wire. I sugest you clean the over boost sense switch too. it's on the intake manifold about 8 inches from the back and on top, got a wire attached to it. disconnect the wire, don't break the connector. Now unscrew the switch with a wrench. clean out the hole that goes into the intake with cleaner. Put that back toghter, don't over tighten. Right that's that all done. You can disable the EGR valve for off road use only of course. mine leaked vacuum and didn't shut off any way. the EGR valve is the mushroom shaped thing on top of and at the very front of the intake manifold. easyist is to put a bb or some thing in the rubber vacuum line at the EGR valve so you don't get any vacuum signal to the EGR. If your EGR leaks like mine did you should make a "blanking" plate, a piece of metal plate to fit between the EGR valve and the intake manifold. It's easy to remove the EGR 2 bolts (allen head) you really dont have to dissconnect the flexable metal hose to put in a blanking plate. Use the EGR vavle gasket to make up you blanking plate, it should be the same shape and have the bolt holes but not the big hole in the middle. use an EGR valve gasket on the top and bottom of your plate and put it between the EGR valve and the intake manifold and bolt it all together. Valve adjustment is not too difficult check out THOMASPIN"s DIY site from the top of the Diesel page. He's got a great site. If you are going to change your Glow Plugs you might want to concider using a Glow Plug Reamer to clean out the holes so the plugs are not covered over with carbon inside the head. Running Diesel Purge is also covered on THOMASPIN"s DIY Site. Adjusting the ALDA and The Turbocharger waste gate you should have a Boost Gage and and exaust temperature gage to ale sure you don't get carried away. The Boost gage is not too expensive but EGT gages do get rather costly. I'm going to put one in when I run out of thing that really need to be done. Fuel filters PRE and MAIN are easy and not too messy or expensive. Make sure you bleed the air out after the filters are changed. I'm going to quit now I'm not used to all this typing my fingers are going to fall off. Good luck