Hey all, working on a 300dt for my friend. Already fixed leaking oil cooler line by cutting in half and putting compression fitting on (see other post).

Two other issues:

won't start off key; will start off jumping starter block to battery just fine. Tried jumping the two purple wires for NSS. No go. Ignition key assembly?

2nd: under the front right control arm, there seems to be something missing. Is it important? He claims there is some kinda clunk from front end when driving. All the bushings for the front end were replaced by PO. This is the only part that seems out of place (see pics).

Thanks!

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Sounds like a NSS issue (a new one) concerning the start problem.

It appears the guide rod front mount has slipped in the first pic.

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83 SD

84 CD

Can't be the NSS if the purple wires were jumped. Could be the ignition switch. Ignition switches have been successfully disassembled and cleaned in the past.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

With that missing, would it cause any movement or play in the front end that might lead to the 'clunk' that was heard?

Also, happen to have a link to the parts area for it? Just went through it all and found all the rest of the parts.

I'm gonna take the ignition switch apart tomorrow AM and see what going on in there.

http://catalog.peachparts.com/ShopByVehicle.epc?q=1982-Mercedes--Benz-300d-Suspension&yearid=1982%40%401982&makeid=63%40%40MERCEDES+BENZ%40%40X&modelid=6190%3AED%7C10000135%3AMBC%7C1504%40%40300D&catid=241464%40%40Suspension&subcatid=241520@@Guide+Rod+Repair+Kit&mode=PD

Guide Rod Repair Kit. $14 at Fastlane (Buy Parts link)

Yes. That part missing will cause clunking. Before doing any work on the lower control arm that involves the spring, do a little research. A standard spring compressor doesn't fit well and creates a very dangerous situation. I can't tell exactly from the pic if you'll need to move the spring.

Ok, some follow up clarification questions...

Check out this pic of the igni switch -- obviously been replaced...

I toned out the wires coming from the 4 pin connector behind the footwell for the NSS. There is a big purple, small purple, purple/white, and black/red. The purple/white is the only wire w/ 12v at key on. So, trying to check the NSS by jumping the two purple's probably won't help me... I tried jumping the purple/white to the big purple, and the motor actually turned over (without the key on), so I don't think that's a good thing.

Second, on the guide rod repair kit, would I still need to compress the spring even with the suspension fully drooped out? Can someone rate doing this job on a hardness/needed scale? lol.

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The service manual shows you need to remove the spring.

Please put your car in your sig or avatar, this will allow folks to help without having to figure out what car by going back and forth.

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guide rod 123:33-515.pdf (700.0 KB, 141 views)

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83 SD

84 CD

For the suspension:-

Just to be clear you'll need to remove the spring. If you don't use a klann spring compressor you'll probably need to file out the hole (you can see this in the engine bay) in the chassis to get the internal spring compressor to fit. Don't try and remove W123 front springs with a standard external spring compressor - you'll probably find that these ones aren't long enough.

You'll probably find it is best to remove the cup that holds the lower part of the spring in place on the lower control arm (LCA) - this makes it a bit easier to get to the bushings. When you fit the bushings make sure that they sit in the LCA "straight" - easier said than done in my opinion if you don't want to adjust the length of the guide rod.

If you change the guide rod length you'll alter the castor setting (and slightly alter the camber setting too).

I think it is best to get an alignment done after you've finished this work - but I don't think everyone will agree with that!

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1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

I bent up my Strut type Spring Compressor compressing the Front Spring.
I replaced the threaded Rod on the Strut Type Spring compressor with thicker Rod and still bent it. So it is not safe to use them on the front Springs.

After that I made a spring compressor that pulled the Spring upwards against the Spring Perch. So the Spring stayed up there whild I did the job.

Home made spring compressor not mine
http://www.peachparts.com/shopforum/showthread.php?p=987680

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84 300D, 82 Volvo 244Gl Diesel

Wow, I had no idea that this guide rod was such a big job.... I guess that still leaves the question: is it needed/worth it? Are there other options? Welding it in place etc???

Yes.

Not any good ones.

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83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 401,xxx miles
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88 Jaguar XJS V12 94,xxx miles. Work in progress.
99 Mazda Miata 183,xxx miles.

IF - the bolt is in place and the upper bushing/bearing/thing is OK -- and

IF - you can get a wrench (19 mm, maybe) under the spring seat -- and

IF - the replacement guide rod kit threads on cleanly to the old part -- and

IF - you can torque down the guide rod properly --

THEN - maybe you could get by with this being a temporary repair to eliminate the clunk and improve steering safety until it gets fixed completely.

Right now you can't align the car due to uncertain/inconsistent caster, the steering may be unpredictable, etc.

The age of the car and perhaps uncertain repair history probably means it needs some other front end work. It's not hard if you rent the right compressor and it re-establishes the safety of the car. If the LCA bushings weren't replaced, or now even if they were the missing guide rod kit may have contributed to their demise from a "wobbly" LCA.

You might get by with a temporary improvement, but long term I'd look at dropping the LCA, replacing the guide rod kit, the LCA bushing, maybe the brake support on the frame.

Thank you. Ordered. I guess easiest just to rent the spring tool from Autozone.

Any input on this things starting issues?

Maybe a bad ignition switch. From the FSM wiring diagram, the small purple taps off the big purple and connects to the GP relay. Jumpering them shouldn't do anything since they should be connected.

Purple/white appears to get power in START, but not run. If you get +12 there with no key in the ignition, that might be the problem. But since the starter isn't turning all the time and only when you jumpered it by removing the NSS, I'd also say the NSS is bad.

Bk/Red is probably back up lights power (upstream of the NSS), but FSM says Bk/Ylw/Red and there should be a Gray/Yellow (downstream of the NSS to the lights). Check for +12 @ Bk/Rd in start/run, check fuse 14. If no power in start/run that's another indicator of a bad ignition switch.

Summary from the FSM diagram (with the NSS connector connected):

Vi/Wh = +12 v in start, 0 other times
Fat Vi = continuity to Vi/Wh in P or N
Bk/Ylw/Red = +12 v in run/start (check fuse 14)
Gy/Ylw = continuity to Bk/Ylw/Red in R
Skinny Vi = connected to Fat Vi at the connector

autozone does NOT have a spring tool that is safe to use on a benz spring.
you either need to rent one from the tool rental forum, or find one on ebay.
KLANN internal spring compressor.
or a reasonable facsimile.
this:

not this:

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