Rocket534
 

1991 300 TE 4Matic, great car with 200,000 miles, 4matic light on dash just lit up and it wont engage 4 wheel drive. Found hydraulic reservoir was low and added correct MBZ fluid, light flickers when engine starts then goes on full time, 4 wheel drive will not engage. Here in Sun Valley, Idaho , we have a lot of snow and I have driven over big ridges that may have rubbed the undercarriage, can't see any damage. I build Bonneville race cars and powerful engines but I don't have a clue about what to check on this car to fix the electronic computer controlled 4 wheel drive.
Can any body give me some ideas. I called the dealer's service writer and he told me to add hydraulic fluid to the coolant overflow reservoir???
Thanks to all.

* Let's hope he meant hydraulic fluid to the hydraulic fluid resservoir! How much hydraulic fluid did you have to add? Over half a liter? Can you see any signs of hydraulic fluid leakage under the hood or under the car? Check hose from reservoir to pump, body of pump itself, and under the car from the transfer case back.
* If the hydraulic system is taking more fluid but it's not leaking out anywhere, it's storing it somewhere. The most likely place is inside the transfer case, where some older-design cases leak internally. Read through another current thread on "4matic".

I can't find any external evidence of fluid leak, but must confess to not once checking the fluid level in the hydraulic reservoir in the past 12 years. It was app. 1/2 litre low, and after filling it, the level has remained constant for 3 days and 50 miles or so. It would appear to me that if the fluid were topped up any sensors would respond to that by returning to normal operation. If there is an internal leak, it is a very slow one. The 4matic light still stays on and 4matic won't engage. I'm assuming it is OK to drive the car as long as underhood function valve is in the "test" position? Thanks

Try this.put the 4 matic switch to run and disconnect the battery for several minutes.this will reboot the 4 matic cpu and clear any error codes.drive it around for awhile and let us know what happens:)

Thanks for the idea Michael.
 

I tried your suggestion about rebooting the cpu, still have a light on the dash and no 4 wheel drive engagement. The snow is melting fast and that will give me some time to fix this before next winter. Thanks, Ron Jolliffe

Does the 4 matic light blink out an error code when you start the car?count the flashes it may give you a hint on whats wrong:)

It usually blinks 3 or 4 times before it goes on constant, [this only after the car has been not running for a few hours] if you shut it off and fire it right up again, the light goes on continually immmediately.

3 blinks i beleive is your brake switch.easy to replace and inexpensive.ill check my documents:)

4 blinks is left front speed sensor.are you experiencing any problems with the ABS?:)

Michael; I really appreciate your thoughts on this issue. I am in Calif. and car is still in Idaho so can't check any further until I get back. ABS works fine and no warning lights flash or stay on.. I am anxious to get back and fix the darn thing. It started after driving through some heavy frozen snow banks and could have pulled off a wire near one of the wheels, but I haven't seen any thing loose from kneeling next to the car and looking under it. I'll keep you posted. Thanks,Ron Jolliffe

1963 220SEb Cab., 1954 220 Cabriolet A, 1981 280 CE, 4spd, gray car, and '91 300te 4Matic

continuing 4matic problem, for Michael Cole
 

Michael; You gave me some help with my '91 300TE 4matic a few months ago. I finally took it to the dealer in Boise for diagnosis, I was told it needed a new transfer case,sun gear and misc. small parts...[$4000.] The service Mgr referred me to an independent MBZ shop, {I have a restoration and hot rod shop and was hoping to save $ on parts} This shop replaced the transfer case,, the test valve[$750] and a sensor switch. Now the 4matic seems to function fine,but the 4 matic light blinks a 2 blink error code every time I start the car, and every time the car comes to a COMPLETE stop, it blinks 2 times as soon as I release the Brake. I can hear clicking under the car as the blinks occur. I feel like the dealer and the ind. shop may have just thrown parts at the problem in hopes of solving it......[this would be fine if they were 10 or 20 dollar parts]
Any ideas about what the distinct 2 blink code representshanks? T

Is it the FUNCTION indicator (the one in the speedo) or the one lower that just says "4MATIC" (which is the malfunction indicator)?
These components are very sensitive for compatability, they could have a bad match between the tx case and the sun gear, there were several changes.
No idea what the clicks are about. Here is some diagnosis info I have, in case it is the malfunction indicator and not the "function" indicator:
http://mercedes.justanswer.com/uploads/rmillerphd/2008-05-04_012344_A1.pdf
The function indicator in the speedo just means the system has detected slippage and is operating, is not a indication of a fault. The lower one, that says "4MATIC" on it means there should be a fault code set.

Typically the first thing you want to check with these old 124 4MATIC cars is what the going price of scrap metal is..........

Where'd the guy get the parts to fix it, any idea??

Gilly

Was just reading about your problem. Sounds like the hydraulic damper in the rear is ruptured. It looks like the rear suspension dampers but it is on the hydraulic valve unit under the left rear. when the damper ruptures what happens is the system does it's self tests and fluid pressure drops. Then the system turns back on when pressure rises. Does the self test over and same problem.

It is pretty easy to diag. with a pressure gauge at the service valve up front.
you will see the pressure drop when you here the clicks. It also might be the pressure switch in the same valve block. The fact it does not do it while driving is a dead give away. The pump is able to pump enought to not have the pressure drop.

Give it a try.

Thanks to Gilly and Whipple..4matic problem
 

Gilly: Now, Now, a guy rebuiding a Sprite is telling me to check scrap prices on my newest MBZ, it is a nice white wagon with only 205K, and aside from not being able to get out of it's own way is a great car to drive on a long trip. The dealer wanted to replace the sun gear with the tran. case, but the ind. shop said not needed....HMMM.
The function indicator works fine, the malfunction indicator blinks twice at every stop. I'll check your referral. and thanks for thinking about this. [I love Sprites and installed a 283 Chevy and Powerglide in one in 1970. Driveshaft ended up about 9 inches long], Now I limit myself to old motorcycles when I need a British fix.
Whipple. Thanks too for your suggestions, I'll figure out how to ck the suspension damper and will post back what I find,

Parts came from MBZ, I'm pretty sure

dont panic but 2 blips usually indicates a problem with the 4 matic control unit.this is a hydraulic valve unit located under the car in front of the right rear wheel.usually covered with a plastic panel.but i caution this could be simply a wiring issue.perhaps something they forgot to reconnect during repair.when you touch the brakes there is a switch connected to the pedal which disconnects the 4 matic valve from power.it makes sense as abs and 4 matic cannot both work at the same time.or possibly you may have a short circuit in one of the solenoids in this valve. :)