Refurbishment of the Starter Solenoid

edited November 2013 in TECHNICAL
This is basically a quick "how to" on solving a sticking starter solenoid.

You will know if you have a solenoid that stays on after you have let go of the starter button. Nothing you can do to stop it turning the Dynastart except to disconnect the battery. Trouble is, you don't always know if it is sticking on if the engine fires up and runs... Except that it will wear your brushes out quickly.
So what do you do?

1: Disconnect the battery
2: Disconnect all the wires going to the starter solenoid.
3: Remove the starter solenoid from the engine side panel. There are two machine screws holding it in place (useless flat blade screw driver heads)
4: Undo the two flat blade screws on the bottom of the solenoid and take the cover off.
5: Undo the two flat blade screws on the top cover - you do not need to take the two locking nuts of the cable posts.
6: You now need a "Instant heat" soldering iron of at least 100 watts.
7: Unsolder the wire which comes through the Bakerlite top on to the spade connector. Use either a de-soldering vacuum pump or solder wick to remove the solder.
8: Whilst heating the remaining solder you can pull the Bakerlite top up and off the wire. Clean the hole as you need to put the wire back through there
on the re-build.
9. Look inside the Barkerlite top and you will see two copper contacts - probably black and pitted. You need to clean these up, make them shiny!
10: Now look at the top of the solenoid itself. The copper bar will also be black and pitted. Use a fine file to clean the two faces up, make them shiny as well.
11. Use some oil, spray grease, PlusGas, WD40 etc, to put down the centre hole of the solenoid.Leave it for a few minutes to work its way down the shaft.
12: Turn the solenoid upside down, Clean up the brass centre post and again lubricate it.
13: Push the brass centre post into the solenoid - let go, it should spring back. More lubrication and more pressing / letting go of the brass centre should make it move smoothly and easily.
14: Make sure the bottom cover is cleaned of any old grease / crud / etc.
15: Use some non-setting gasket sealant to put a seal all round the edge. Put the cap back on and do up the two screws.
16: Turn the solenoid back over. Use some more non-setting sealant to seal round the edge so when the Bakerlite top is put back on it provides a good seal. There is a gasket on there, but it probably has seen better days and wont keep the water out just by itself.
17: Put the Bakerlite top back on make sure the wire from the coil goes up through the hole to the spade connector.
18: Put the two screws in and do them up.
19: Use the soldering iron again with new solder to solder the wire from the coil back on to the spade connector tag.
20: Couple of small things to do now; put some sealant on to the two bottom screws to stop ant water from going in via them. Put some grease on top of the two screws in the Bakerlite top. (Why grease? Well, it is easier to remove if you need to open it back up again than getting sealant out!)
21: All Done, bar installing it back in the Haflinger.

Now I am quite sure some one will have forgotten to make a note of where the wires go! So for those people here are the details.

1: The thick wire from the Dynastart goes to the big post on the solenoid nearest the front of the vehicle.
2: The thick wire from the Battery goes to the big post on the solenoid nearest the rear of the vehicle.
3: The two red wires with ring tags on them go to the big post on the solenoid nearest he rear of the vehicle.
4: The brown wire with the female spade connector goes to the spade connector tag on the solenoid.

This is how mine was wired - a 1973 LWB 703 - Yours might be different, so better that you make a note of which wires go where before you take the solenoid out!

I took pictures, but haven't had time to resize them all yet to be able to upload them along with this "How to". Hope it helps someone deal with theirs considering the original Bosch Starter solenoids are no longer available.



  • edited November 2013
    Hi John,  Many thanks for sharing your info on ' Starter Solenoid Refurbishment ' very informative, your the first posting in the ' Technical Section ' hope this will encourage others to post.
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