Fig 1 Fig 2 Fig2a
Fig 3 Fig 4
Starter Replacement (05/23/2003)
The Problem
I was having an intermittent with my 1989 560SEC (1 out of 20 times) starting
the engine. When I was engage the starter the starter would just spin and
not turn over the engine. When I released the key I could hear the starter
stop spinning and just before it stopped I could hear the starter make a clunk
sound and stop. I would then try to start the engine again and it would
start right up. I found the starter's end pilot bearing was gone and the
tip of the starter case was worm from the starter shaft flopping around (Fig1
& Fig2)
The Job
There are 2 12mm bolds that secure the starter to the bellhousing, the top bolt
could not be reached with dropping the exhaust system. The precat in
directly in the way. I removed the entire system, because I had some other
work to do which require access to the drive shaft.
- Start by disconnecting the neg. lead to the battery.
- Securely jack up the car front end and support on heavy duty jack stands.
- Spray some WD40 on the 2 nuts that secure the precat to the manifold.
These nuts are attached to the manifold.
- Using a long extension and 13mm socket with swivel, very carefully break the
bolts loose from under the car. Work the bolt back and forth allowing the
WD40 to work its way around the threads. Take your time and be patient, it
will loosen up to where you be able to use you fingers to unscrew the
bolt. You DEFINITELY don't want to round off the bolt head or break it
off.
- Disconnect the two power leads to the starter.
- Using a 10mm allen socket and breaker bar, loosen the 2 starter bolts and
remove. Lower the starter from the front.
- (I have not reassembled yet as I got a question about some parts that came out
that I'm not sure about)
The Question:
When removing the starter two spaces (or shims Fig3) came
out with the starter. Still stuck to the bellhousing was a centering plate
(116-151-03-45). (The centering plate is required when installing a
smaller Bosch starter (004-151-78-01-88) which when into production from1988
on. Apparently, this smaller starter can be used in pre-1988 V8's as long
as the centering plate is used.)
When I purchased the starter from MB, we went through the parts book and it had
no reference to these other two spacers. My question is are these
spacers required???? I'm wondering if they were added by someone during
some repair or to do a temporary fix on a bad starter????
I measured the distance of the starter-side face of the ring-gear to the
start-mounting surface of the bellhousing and it was 15mm. Fig-4
shows where the starter gear would engage the ring-gear with (yellow) and
without the 2 shims (red). I was thinking that with the space
installed it would be catching the end of the starter gear, putting more stress
on the pilot bearing and that might have caused the failure...
Any thought or insight would be most helpful as I'd like to get this back together ASAP and I like not to have to pull this thing apart again...
Thanks
Chet
(Click image to see larger image)