Starter runs on

[fasted]

I have a 1980 450sl and this morning the car failed to start. Imagine my surprise when upon releasing the key from the start position the starter kept turning the engine over. In fact I was able to remove the key from the ignition with the starter still grinding away.

Thankfully this happened in my garage and I managed to get into the battery box in the trunk to remove a battery cable before the starter had a meltdown.
On reconnecting the cable and turning the ignition key, the same result.

What is strange is that the engine did not fire during this episode leading me to believe that it must be a fault at the mechanical / electrical connection behind the ignition tumblers that is causing this.

Has anyone else experienced this?

fasted

[RAYMOND485]

1984 300d Turbo 139k
Replace The Starter.

[tecqboy]

It is not unusual for a starter motor to fail in this manner. The internal solenoid contacts fuse shut. Sometimes in an emergency you can rap it real hard with a hammer to break the contacts. But before I'd buy a new starter, I'd use a volt meter to check the voltage at the control contact ( small wire ) on the starter. ( Disconnect the heavy cable from the battery first. ) If there is voltage when the key is NOT in the crank position, then you could have a bad ignition switch or starter relay ( if your vehicle uses one. )

[230/8]

fasted:

You challenge will be gaining access to the starter for anything you want to do to it. SLs are really cramped to work on; a lift is a lifesaver. If you can get the blasted thing out then you are probably money, time, and aggravation ahead to have a very good shop rebuild it. Most over the counter rebuilds are poor quality, regardless of brand name on the box. Try to locate a rebuild shop with MB experience; this may be as easy as canvassing the indys in your area to find one or more that send starters out for overhaul. A good heavy equipment electric shop would be a good bet.

Good luck,

230/8

[fasted]

Thanks for the replies. This couldn't have been a fused starter solenoid. When I pull the battery cable the starter stops turning. On reconnecting the cable the starter does not start turning again until the key is in the start position. The engine also doesn't start which it would if the ignition swithch was good and only the starter solenoid was fused. That would really screw up the starter or the ring gear wouldn't it?

Have installed new ignition switch and problem is solved. Switch is easy to install after removing steering wheel and cluster.

Just one of the joys of owning a 26 year old car.


Ed

[New 450sl Owner]

My 1980 sl just developed this very same problem, but the starter is still engaged after reconnecting the battery. I will proceed with the test recommendation of TECQBOY; hopefully the problem will be resolved without removing the starter. I can't even locate the starter upper mounting bolt much less get a wrench on it! Do you or another have anyinformation about removing a starter from a 117.985 engine?

[MunichTaxi]

and slip it next to the transmission, longitudinally. Turn the rachet from near end of transmission and under the car.

[450slcguy]

Originally Posted by New 450sl Owner

My 1980 sl just developed this very same problem, but the starter is still engaged after reconnecting the battery. I will proceed with the test recommendation of TECQBOY; hopefully the problem will be resolved without removing the starter. I can't even locate the starter upper mounting bolt much less get a wrench on it! Do you or another have anyinformation about removing a starter from a 117.985 engine?

Man your not kidding there. When I first got my car 80 SLC, the starter would make a strange noise sometimes. I pulled it up on ramps to check out pulling the starter. That upper bolt looked impossible to remove. Luckily, I noticed the solenoid wire was hanging by a thread because it was hacked by a halfassed repair job. Just enough slack in the wire to strip it down and reattach with ring terminal. Extremely tight area to work in.

[Strife]

There is an (expensive) MB tool specifically for this purpose.

[450slcguy]

Originally Posted by Strife

There is an (expensive) MB tool specifically for this purpose.

Who would have thought. I don't think the long long ratchet extension as suggested would work. The bolt is up on the inside part of the starter, you can't even see it, much less reach around the trans from 2+ feet away. I'd like to see what that special tool looks like. Has anyone here actually done this job?

[fasted]

Its true what they say, the best things in life are difficult. Seriously, I have removed a 450SL starter twice and it is relatively easy if you know the trick.

1 - getyour car off the ground as high as possible to give yourself some room to work. Do not remove - only loosen the lower starter bolt (the easy one) yet
2 - Assemble an extension that is about 28" long overall with a universal joint and 10mm allen head socket at one end.
3 - Insert this assembly from the back side (from rear of car) of the transmission torque box (plate steel reinforcement under transmission) and feed it through to the upper starter bolt. Note that there is a spot just aft of the starter bolt that you can get a finger or screwdriver into to help guide the socket. It is also wise to securely tape any joined sections of extension to keep them from coming apart.
4 - remove the upper starter bolt only as far as is neccessary to get it out of the starter itself. Do not remove the bolt all the way from the hole in the transmission bellhousing as it will be a ***** to line up again later. Also do not remove the socket and extension assemble from the head of the allen bolt either for the same reason.
5 - remove the lower starter bolt and the wiring off the hot terminal and the starter solenoid. Did I mention to disconnect the battery first?
6 - Do a David Copperfield and manouver your starter out of its orifice and go have a beer.
7 - Installation is the reverse of removal.

Good luck with this. It is really not all that difficult once you know the trick.

Ed

[vwnate1]

THANX , Ed !

My 350SLC's Bendix is just beginning to slip so I know it's just waiting for me to go out in the rain , or wear a suit or take SWMBO out in it before it dies completely....

I was planning to put it on the jack stands to-morrow anyway but now it's raining

BTW : it is very common for the ignition switch to wear out so it stays in the " start " position , you must manually turn the key back to the " run " position else the starter continues to grind as memtioned in this thread....

Lotta German cars have this same fault .

[imbenzcrazy]

Fasted: This is a great thread with excellant details on this tough removal. You really made an impossible job more realistic! Thanks.