1978 300D new to me, a few issues / questions
 

I got another mercedes diesel, yeah!!!
Good power, shift is a little rough from 1st to 2nd...
Brakes seemed good, but when I took it on drive the pedal went slack I had to pump to get any pressure. It resolved itself and seems fine. Any ideas why this happened? Oh, and there is no heat or air inside..

Welcome to the early w123's owners group!

Now you will get to start learning all the headaches of the early years. You'll also find out it is probably a 1977 which is the first year! Would love to see photos!

Your first issue is your brakes are probably getting hot! What cured mine was a brake flush, your brake fluid is probably so dark it resembles the motor oil.....I would suck out all the fluid out of the reservoir and bleed the system. You may be due for vacuum pump rebuild, but usually what you described is because of over heating brakes or a bad master cylinder.

No heat and no air, is because you have the evil servo unit! Google it....see if you have the aluminum servo or plastic, and see if its cracked or leaking....and then I can start telling you what to do next...

Ok, I looked at the fluid it wasn't dark, but I will do a flush anyway..

I also have a 1987 300td, veggie rescue! With issues. I have replaced screen and both fuel filters several times, algae in the tank. Still have tons of gunk, going to drop tank and have it steam cleaned.. It has no power up hills.. And my throttle system is a mess.

So, back to the 77/78? The shifter has a lot of play in it also??
I will add pic when I figure out how to do it.


1987 300td wagon
1978 300d

Oh yes I will never rescue another veggie mobile unless it was dirt cheap to free and it really nice shape. Wish I could be of more help on the 87 but I haven't discover one yet, so no experience on those engines.

If your fluid is clear, chances are its the master cylinder...they are dirt cheap. It may pay to just replace it and bleed the brakes, check for fluid on the inner to make sure its not a bad wheel cylinder.

A lose shifter is bad bushings, check the video below in location.

Automatic Shift Lever Bushing Troubleshooting and Repair on Older Mercedes by Kent Bergsma - YouTube

And here's a DIY article
http://www.benzworld.org/forums/w123-e-ce-d-cd-td/1417360-diy-console-shifter-bushing-replacement.html

More data needed
 

Is this a manual or automatic transmission ?

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78 300d
 

It is automatic trans, I'm going to replace the shift linkage bushings after I fix the brake problem..I'm not sure how to bleed the brake system, help!

Sorry my legs aren't long enough to give a helping foot :D

What I did was to use a clear plastic tube from the bleeder to a jar....loosen the bleeder, have your helper push the peddle down...tighten bleeder...loosen...tighten and watch for the fluid to become clear and free of bubbles....start with the tire farthest from the cylinder aka rear passenger to driver rear to passenger front to drivers front...

Or if you want do it one manned....get a power brake bleeder...

Here's a video, you can find them cheaper then he offers or make one
http://www.youtube.com/watch?v=zg1DcTgmY98

Gwenn:

Both issues could be solved at once. On my '79 300d the "barb" leading off of the main vacuum line to the master cylinder was cracked, not visible, brakes and tranny issues went away after I epoxied fitting.

Tom

"slack" pedal = bad MC
"hard" pedal = bad (brakes)vacuum

Tranny in the '78 is 100% mechanically controlled. No trans VCVs or
modulators like later w123s.

I am having both the pedal is hard when brakes are working, then goes slack when it gets hot..
I drove it today no problems, then it started to smell really hot and smoke a bit on the passenger side tire??

You have a stuck caliper, stop driving it before you lose your brakes....a 2 ton car can do some serious damage rolling.....a brake bleed may cure it, but in all reality....you need new calipers, new discs(they warp with heat) and a brake bleed....mine as well change the master cylinder while your at it....I was luck mine went on only a mile from my house, so I drove back with the ebrake, then immediately bleed the brakes......when you have a stuck caliper, it causes heat which in turns boils the brake fluid....thus a peddle goes limp...

Cooljjay: I don't know what your issue with WVO is. WVO is close enough in viscosity to diesel to be used straight, despite what everyone else says. My buddy runs his car on straight WVO and he doesn't even filter it because everything burns up in the motor. Free fuel rocks when Big Oil hasn't paid you to say otherwise.

78 300d
 

I checked the caliper and its ok, I pushed the pistons in..I'm going to change the MC and bleed the system..hope that works..

Hot enough to smoke the front wheel is not normal. May have a one way valve effect in the brake hose. Whatever there is something very wrong to find.

Brake hose valve 78 300d
 

How do I find out if this is the problem?? The caliper stuck I'm not sure why..