Mercedes-Benz Forum banner

1 - 7 of 7 Posts

·
Registered
2000 ML320 LHD
Joined
·
666 Posts
Discussion Starter #1
Hello all,

Been a very long while.

Hope you're all doing well.

So, I tried the method of repeated light tapping of the low range motor after my low range light blinks at start up then stays lit.

This didn't work despite repeated attempts for days to weeks.

All the usual accompanying codes were stored & some current.

This happened barely a week after I last serviced the low range by the usual recommended method in the owner's manual.

Some of the many things that could go wrong with the motor range from:
1. Decreased magnetism: as magnets age they lose their magnetism, this effect is more with high temperature exposure.
2. Fragments of magnet.
3. Dried up grease which could make things stuck.
4. Others

After unsuccessful attempts with the light tap method as well as the drill hole-spray WD40 method, I decided to tear down the motor.

One side of the magnet has fractured with plenty sharp magnet fragments & particles like crusted grease were noticed.

The magnets were glued to the inner surface of the metal casement & the glue has become weak with age as well as the power of the magnets. Also bear in mind one's light tap might yield more N than another's.

I ended up fixing the problem by replacing with a used motor.

What we can do going forward is;

1. Tear the motor apart: making sure you note placement & orientation of parts & pieces. This is a very important step.
2. Clean off dirt & be careful not to damage contact brushes or coil winds.
3. Get a very strong magnet coin or bar & rub on the surface of each sides of the inner casing c-shaped magnets for about 5mins to renew the magnetic strength.
4. Re-grease metal gears.
5. Put motor back together.
6. Reinstall low range motor & check functioning.
I have just done this for a friend's ML320 & the low range works as should. Nobody should be afraid to take it apart as it is doable & not difficult at all.

#Time to ditch out the old light hammer & drill-hole-spray-WD40 method to unstick low range motor.
Let me know your thoughts.
 

·
Registered
1999 ML430
Joined
·
1,523 Posts
Thanks for the write-up. I think all of us old timers will still try the light tap with a hammer first, but good to know you have posted the next step without buying a new motor... hope your W163 is still running good !
 

·
Registered
1999 ML430
Joined
·
1,523 Posts
Congratulations...just getting broke-in !!

Not sure if it helps or not, but I occasionally engage the low range on my 99 ML430 just to make sure it will not be an issue if I ever really do need it.....so far so good and its a 1999 !!

I always do this on a dirt road close by just to prevent any binding that might occur.
 

·
Registered
Dallas, Texas
Joined
·
7,006 Posts
Congratulations...just getting broke-in !!

Not sure if it helps or not, but I occasionally engage the low range on my 99 ML430 just to make sure it will not be an issue if I ever really do need it.....so far so good and its a 1999 !!

I always do this on a dirt road close by just to prevent any binding that might occur.
There is no risk of binding. All three difs are open.

I have note in my Google calendar. "exercise TC" every first Monday of the month.:)
 
1 - 7 of 7 Posts
Top