82 300D Suspension, Alternator Air-in Fuel Questions - PeachParts Mercedes-Benz Forum

imgolden · #1 09-09-2020, 06:55 PM

Hi all,

I am solving a few different problems on my 300D, your help is very much appreciated.

-I need new outer tierod ends. I see they are available in left or right-hand threaded. I assume I purchase one of each?

-I need lower control arm bushings. I read somewhere that W126 bushings are compatible and easier to install, is that true. Also, what else should be replaced when doing this job?

-My brake warning light, parking brake, and low-volts light all stay on when started unless I tap the gas or pull the parking brake. Additionally, under a heavy load (lights, radio, blower), the battery reads 12.5v, under no load it reads 13.6v - is this a bad voltage regulator?

-My #4 cylinder injector hardline keeps filling with air. No fuel leaks, but after the car sits I have to bleed the line for a few seconds and it runs better. I assume I need to replace the line? I inspected it and I couldn't see any cracking, but, it's probably small.

Thanks very much!

Sugar Bear · #2 09-09-2020, 09:19 PM

Tie rods, depends on what is in there now. Look at the angle of the threads that will tell you L or R. Compare the angle to any regular bolt, that is R (common) thread. IMO, solve the problem by replacing the complete tie rod assembly v just the outer ends. Use the best steering parts you can afford.

Lights staying on, extinguishing when releasing the brake may be a poor connection/weak instrument cluster ground.

Voltage going to 12.5V with a heavy load, is the 12.5V @ idle? Sounds normal unless the voltage doesn't increase with RPM. Does it? As current demand/amperage increases the voltage will drop as long as the alternator output voltage exceeds the battery voltage, the current/amperage is flowing toward/charging the battery. This was the beauty of old school dash ammeters, if the ammeter was not in the negative you were good to go.

Is the voltage regulator ok? Probably yes but without being able to measure amperage output and voltage simultaneously it is hard to tell. Replacing the VR on these is good maintenance.

Lower control arm bushings, perfect time to replace lower ball joints if needed. Use the best suspension parts you can afford.

Good luck!!!

imgolden · #3 09-09-2020, 09:43 PM

Thanks Sugar Bear.

Tierods:
I originally thought I'd replace the entire assembly as well, but it looks like the inners (and drag link) were replaced not too long ago, seemed like a waste I suppose.

Voltage Regulator:
I'm getting 12.5v on the alternator at idle, slightly more when I play with the throttle. Not a whole lot more. I may just replace the VR just to be safe. The car has never left me stranded, so the charging system seems fine.

LCA:
Good idea on the lower ball joints. I might just do them anyway. I am buying all Febi Bilstein, are they pretty good for this? I can't afford OEM, so this is the next best from what I can tell.

Diesel911 · #4 09-09-2020, 10:46 PM

Quote:

Originally Posted by imgolden

Hi all,

I am solving a few different problems on my 300D, your help is very much appreciated.

-I need new outer tierod ends. I see they are available in left or right-hand threaded. I assume I purchase one of each?

-I need lower control arm bushings. I read somewhere that W126 bushings are compatible and easier to install, is that true. Also, what else should be replaced when doing this job?

-My brake warning light, parking brake, and low-volts light all stay on when started unless I tap the gas or pull the parking brake. Additionally, under a heavy load (lights, radio, blower), the battery reads 12.5v, under no load it reads 13.6v - is this a bad voltage regulator?

-My #4 cylinder injector hardline keeps filling with air. No fuel leaks, but after the car sits I have to bleed the line for a few seconds and it runs better. I assume I need to replace the line? I inspected it and I couldn't see any cracking, but, it's probably small.

Thanks very much!

http://www.peachparts.com/shopforum/diesel-discussion/380871-w123-lower-control-arm-bushings-options.html

No one has posted a thread I can remember where one fuel injection hard line gets filled with air.

Your alternator issue is not as common as it simply not charging.

Loose alternator belts can cause the symptoms you posted for the alternator.

The wattage of the charging indicator bulb makes a difference because it excites the alternator to charge. Some sources I have read say 2 watts some 3 watts.

remove and clean the contact areas of your ground cables and of course the battery posts. The Engine to Chassis ground is on the left side under the car.

The Brushes are built into the voltage regulator but can be changed. If they are 2mm or less the brushes are worn out. Also when the voltage regulator is out look inside at the slip ring and see if it is badly worn.

One side of the voltage regulator is grounded to alternator's housing that has to be corrosion free and inside with the voltage regulator out there is a metal fingers that also contacts the regulator. See the fingers in the attached picture.

ALTERNATOR DIODE check with volt meter

With your meter across the battery, on Volts DC, you should read 12.5 - 14VDC

If not, set your meter to Volts AC and you should have a reading of ~100mVAC.
If the VAC is too high, then look for a rectifying diode failure. If VAC is OK but the VDC is not correct, then the problem is with the voltage regulator.
See post 20
http://www.peachparts.com/shopforum/diesel-discussion/332195-1980-300td-alternator-diagnosis-s-2.html#post3097790

Diesel911 · #5 09-09-2020, 10:55 PM

Quote:

Originally Posted by imgolden

Thanks Sugar Bear.

Tierods:
I originally thought I'd replace the entire assembly as well, but it looks like the inners (and drag link) were replaced not too long ago, seemed like a waste I suppose.

Voltage Regulator:
I'm getting 12.5v on the alternator at idle, slightly more when I play with the throttle. Not a whole lot more. I may just replace the VR just to be safe. The car has never left me stranded, so the charging system seems fine.

LCA:
Good idea on the lower ball joints. I might just do them anyway. I am buying all Febi Bilstein, are they pretty good for this? I can't afford OEM, so this is the next best from what I can tell.

Lemforder ball joints and other suspension parts have a decent rep at a decent price and were made in Germany; at lest the ones I got in the past were. Febi and Meyley have a few German and Euro made parts but also have PRC made parts and parts from other Countries.

Repair Links
Fast navigation http://www.peachparts.com/shopforum/diy-links-parts-category/146034-fast-navigation-do-yourself-links.html

imgolden · #6 09-10-2020, 01:35 AM

Thanks all, I’m going to check my alternator belt tension tomorrow and report back my findings.
I had assumed the voltage regulator because the problems arose shortly after I improperly jumped another car (black cable on negative battery post) sorry, I should’ve mentioned that earlier.

Regarding the fuel line, here’s the background:
I have been trying to figure out an issue with the engine occasionally stumbling during cold start. Glow plug system is working perfect, new glow plugs too. Valve adjustment just done.
I had read somewhere else (can’t find it now) that another person had similar issues and discovered it was a crack in an injector line. So, i thought I’d test this idea by cracking all the lines while the engine is running. All lines start spitting fuel immediately, except #4. I’ll crack the line, nothing happens, bubbles, then squirting. The car will run a little smoother too if I do this little dance.

Then, I shut off and restart, everything starts over again. My thought is this may mean a tiny crack in the line, or perhaps the fittings aren’t sealing. I’ve inspected visually and found nothing, and it doesn’t leak fuel....

Does that make sense?