How to test early 4-matic? - PeachParts Mercedes-Benz Forum

thorsen · #1 10-01-2012, 10:47 AM

I am looking at a 1991 and 1992 4matic sedan and wagon. Other than finding a gravel lot and peeling out, how can I test if the 4-matic is working?

pawoSD · #2 10-01-2012, 08:12 PM

They are some of the most complex/problematic versions of this model of car, personally I would avoid owning one. Snow tires are a much better/cheaper solution.

That said, you don't really need to "peel out" on dirt or gravel to test it, firm throttle on any unpaved surface will cause wheel slip which should trigger it (and it will be noticeable because it is an "after the fact" type 4wd so it will engage during slip)

Its far from very sophisticated since all it does is give power to the front wheels should the rear be spinning in comparison.

duxthe1 · #3 10-01-2012, 11:01 PM

I personally love mine. The basic test is.... does the 4-M light illuminate with the key on and go out once started? Otherwise the main check is to pull the plug out of the side of the t-case and see if there is excessive fluid inside. If you pass both these tests you have a winner.

The function is that if wheel slip is detected it will send power to the front wheels. If slip continues it will then lock the rear differential. Any time the system is active it should light the triangle light in the center of the speedo.

FWIW, I managed to chirp a front wheel recently, the smile lasted at least half an hour.

Gilly · #4 10-02-2012, 07:53 AM

Quote:

Originally Posted by duxthe1

I personally love mine.

That's the way early 4magics are, love or hate.
I think "hate" is too strong to describe myself, but I agree that I would not advise someone buying one.
EVEN if it is working properly they still drive like tanks, the steering feels very heavy, even on a new one (I was working in a dealership when they were new, I remember. You didn't have to look at the warning lights, you could tell just buy driving it you were driving a 4magic ).
Look at the front springs, you really going to buy that?? yeesh.

Gilly · #5 10-02-2012, 08:04 AM

Oh, I might still have the intro manual for one of these, I am gone for a couple days starting in an hour or so, can check when I get back if you want.
Thought I just had is possibly getting it off the ground on a hoist and driving it (running it in gear and see if that has an effect, can't remember right now if that would work or if all the wheels will lock instead of spin).

PS yes I agree with PawoSD on his 2 observations as well. There is a "TEST" lever under the hood, orange I believe and inside the right fender, again I would have to review how this is used, might be spelled out in the owners manual or might be a shop-only thing. But yeah if you pull the TX case fill plug and it pukes it's gut out, RUN. I'd run from this on general principle, but if it does this, it's more like "Run Forest, RUN!!!"

thorsen · #6 10-03-2012, 08:10 AM

Thanks everyone. I think you talked me out of it. There's just too much potential downside.

JamesDean · #7 10-03-2012, 12:19 PM

Quote:

Originally Posted by Gilly

That's the way early 4magics are, love or hate.
I think "hate" is too strong to describe myself, but I agree that I would not advise someone buying one.
EVEN if it is working properly they still drive like tanks, the steering feels very heavy, even on a new one (I was working in a dealership when they were new, I remember. You didn't have to look at the warning lights, you could tell just buy driving it you were driving a 4magic ).
Look at the front springs, you really going to buy that?? yeesh.

THAT SPRING.

JohnM. · #8 10-03-2012, 11:01 PM

The first time I saw a 4-MATIC car at the junkyard, I thought that the Hulk had come through and stretched out its front springs.

duxthe1 · #9 10-03-2012, 11:24 PM

For all the grief I hear about them, I don't think they are all that bad. Aside from internal seal leakage, the case itself is bullet proof. The electronics aren't terribly complicated and the hydraulics (aside from the t-case) are at or above par.

While they are great in inclement weather conditions, most people don't realize how awesome they are on dry pavement. Try to push one into understeer and you'd be amazed at how much grip it has.

JamesDean · #10 10-04-2012, 08:10 AM

Quote:

Originally Posted by duxthe1

For all the grief I hear about them, I don't think they are all that bad. Aside from internal seal leakage, the case itself is bullet proof. The electronics aren't terribly complicated and the hydraulics (aside from the t-case) are at or above par.

While they are great in inclement weather conditions, most people don't realize how awesome they are on dry pavement. Try to push one into understeer and you'd be amazed at how much grip it has.

You know, most of the Benz's I see on the road are 4Matics. Albeit newer 4Matics, but 4Matics none the less.

duxthe1 · #11 10-04-2012, 08:50 PM

I'm not a big fan of the newer, open differential, brake the slipping wheel 4-matics. I prefer the positive engagement of the old ones. When I feel the case lock, I know its going where I've got the front wheels pointed.

brooktre · #12 10-04-2012, 10:02 PM

My 91 sedan is virtually unstoppable in the snow. Understanding the car and be able to fix it yourself is a must and as was said earlier, they are not hard to work on. There is a group of owners that communicate by email and share knowledge. One is rebuilding his transfer case now.

thorsen · #13 10-05-2012, 01:00 PM

For less coin I was able to pick up a similar vintage Range Rover.
Not that the Rover doesn't come with it's own set of issues, but for a non-primary car I'd rather spend a weekend afternoon cleaning electrical connectors with a wire brush than having to rebuild an early 4-matic transfer case.

Thanks everyone for their input.

duxthe1 · #14 10-05-2012, 08:46 PM

Quote:

Originally Posted by brooktre

One is rebuilding his transfer case now.

As a 15 year MB tech, and someone who both owns this case as well as seen inside it, the chances of rebuilding this case without the MB special tools is virtually 0. There is a seal that has major positive rake, that is installed past very sharp shoulders, deep inside the case, where access is EXTREMELY limited. Myself and several other exceedingly qualified techs have attempted to replace that seal without damaging it, to my knowledge nobody has succeeded without the tools, for which MB wants a few K $$$$

If I can ever get my hands on another case core, I may use my lathe to attempt to make my own seal installation tools.