Garage => Mechanicals => Topic started by: mwildeman on 21 August 2006, 07:44 AM

Title: Starter
Post by: mwildeman on 21 August 2006, 07:44 AM
I have a 1973 450SE, lately it seemed like the starter was dragging a bit. i removed the starter and cleaned all the connections, bench tested the stater and solenoid and re-installed the starter. Now, the motor and solenoid work everytime but the starter does not engage with the flywheel. i can hear the solenoid working if i am under the car and use a jumper. I can't figure out why the gears on the flywheel and the starter are not connecting.

any help will be greatly appreciated.

Title: Re: Starter
Post by: Denis on 22 August 2006, 07:50 AM

When you had the starter out, did you clean the mechanical parts ? and lube with graphite ?

These parts can get grimy and a good cleaning with solvant and relube can restore the full motion towards the ring gear...

Good luck


Paris, France
Title: Re: Starter
Post by: oscar on 23 August 2006, 07:44 AM
Hi Martin,

Is there any crunching or contact of gears?  Or does the solenoid clunk and you just get the free spinning of the starter motor?  I'm watching with interest as my starter seems to hold on for too long sometimes.

My only thought is that barring a few missing teeth from the ring gear, I agree with what Denis eludes to and say that the solenoid isn't throwing out the armature far enough and would suspect a clean and lube may fix this problem.  Welcome BTW.
Title: Re: Starter
Post by: Denis on 23 August 2006, 01:34 PM
Just to make the point :
The solenoid must not stick in its housing - clean - use graphite powder sparingly to lube
The pinion with teeth that the solenoid pushes back to contact the flywheel slides on the motor shaft  - clean - use graphite powder sparingly to lube
You can use grease atthe fork pivot and at the conencting point to the solenoid and the sliding section on teh pinion with th teeth.

Sorry for the strange terms, just showing that I am french  ;)

The point is to lube but sparingly. If you do this and barring some installation problem (misalignment), it should catch. If not, the solenoid is not very healthy  :(

Good luck


Paris, France

Title: Re: Starter
Post by: s class on 24 August 2006, 12:34 AM
My suspicion is solenoid operation.  Either the solenoid is "tired" or it isn't getting enough voltage.  THe second option is a common problem with older cars because the wiring builds up resistance.  What I did is to use the original solenoid wire to drive a relay which switches the battery voltage directly onto the solenoid.  THis is an old solution that fixed the problem, but it is not well thought of in many circles because there is a tendancy of the relay to stick, causing the starter to remain engaged after the engine has fired.  THis is known as "running with the engine" and usually results in destruction of the starter and possibly ring gear.  So far though I've been lucky. 

Does your car have an aftermarket electronic immobiliser?  If so these are also frequent culprits for reducing the voltage supplied to the solenoid, with the same symptoms as you would have for old, higher resistance wiring.

Ryan in South Africa
Title: Re: Starter
Post by: john skene on 25 August 2006, 01:05 AM
If your solenoid is throwing in and out (clattering) it is a sure indication of voltage drop by either a bad connection or a weak battery. Check the battery SG or try charging your battery overnight and see if there is any difference.
Title: Re: Starter
Post by: Denis on 25 August 2006, 01:30 AM
Hello fellows

One problem with solenoids is that you cant tell the condition of the internal contacts unless you dismantle it. When power is applied to it, it needs a firm strong current to "pull hard", if the internal contacts are toasted, that will not happen...a new solenoid is often required :( (even of the mechanical parts behind it are doing their job and properly cleaned/lubed...

Bonne chance


Paris, France
Title: Re: Starter
Post by: koan on 25 August 2006, 02:24 AM
Hi Denis,

The two light gauge wires, one from the starter switch, the other to the ballast resistor, did they go back on the right way?

Title: Re: Starter
Post by: mineson on 11 September 2006, 02:20 PM
Hello Martin,

I have been through this one on a 77 450SEL, so I've learned a few points of failure.   

The first thing to check are the wires that run from the solenoid to the starter relay.  If these are the fabric-insulator type like mine, be sure to clean them thoroughly of grease and dirt.  I have a theory that grease+dirt+water creates a conductive layer that shorts out during the the loop to the relay and back.  Degrease the wires, dry them out, then seal them with a coat of liquid electrical tape (or your choice of non-conductive goop).  Bad wires make the solenoid stick, which will break things that cost much more money to fix (see below).
Cost: US $25 for wire cleaning, drying and sealing sprays and or goop.

The next thing is the starter relay itself.  It is one of those multi-use relays that live in the fuse box (I lovingly call them "87A"s).  Get a new one and see what it does (this same part is used at least 4 times in various positions in the electrical system, so having a good one in the glove-box for emergencies or troubleshooting isn't a waste of the $50 price).  You could swap one
Cost: US $50 for a new relay

If still no luck, remove the starter and take a look at the ring gear on the flywheel.  Turn the engine a few degrees and check again.  If any teeth are worn down, the ring gear might need to be replaced.  The part is only US$150, but the labor will be expensive because they have to drop out the transmission.  It cost me US$700 in labor!
Cost: US $850 in parts and labor.

Title: Re: Starter
Post by: revilla on 21 August 2019, 03:23 PM
Hello everyone,

One of my starters spins without engaging once in a while.  Ring gear's fine.

While searching for information I came across this video.  Impresive.

One day... one day...