TR2/3/3A Starter Solenoid Question

My starter switch fails intermitantly. It seems that when failure occurs, I can turn the engine over with the button on the solenoid and the push switch works next try. First of all, does this indicate a problem with the solenoid or push switch on the dash? Secondly if the problem proves to be with the solenoid, is it serviceable or need to replace? The dash sw has continuity when depressed.

I would suspect the solenoid. My recollection is that there is a disc in there that the magnet pushes against the high current connections - as I recall that disc can become corroded or in some way less conductive.

Next time the dash switch does not trigger it you might (instead of pushing the button on the solenoid) just use a short wire to briefly jump the post with the battery cable to the terminal for the white/red lead. If that makes the solenoid work then your switch or ignition wiring is suspect. If nothing happens than that would suggest the problem is the solenoid.

Why does it resume working after you have manually exercised it? I'm thinking that disk in the solenoid moves a bit each time so you get off the bad spot that was the problem.

Searching a bit --

I don't know that you would have much success opening up a solenoid, cleaning it and (the hard part) getting it back together -- but here is a photo array by someone who did 'fix' a balky one. Note that he is working with 2 solenoids - one he takes apart just to see what is in there and another that he drills to enable cleaning, drying and reuse:

https://www.jag-lovers.org/snaps/snap_view.php3?id=1458846628

Thanks Geo, I'll try the jumper next time.

When that happened to me, it ended up being the starter motor itself going out...
Cheers
Tush

That's interesting. The starter never hesitates when it's activated by the button on the solenoid. But it is sure something to check. Thanks.

Nice stuff Geo thanks for posting. I never would have thought of that. I have tried to think of ways of opening the pot metal up and resealing somehow, but have not tried yet.

Yes, my experience was that I sent my push button solenoid off to Cox Automotive in the UK, which is reputed to be the best around. But they said they could not repair my unit! That was stunning to me as it doesn't seem too complicated an item. I wanted to use my '54 date stamped piece, which I think is a nice little touch. So now I am thinking about trying the old "drill through the bakelite to clean the innards" trick described above!

Dan

I tried the jumper and nothing happened but did see a slight spark in the vicinity of the mounting bracket. With the jumper attached I wiggled the solenoid and it came to life. Going to attack the mount to clean and solidify the ground.
Thanks again Geo for the great trouble shooting advice.

I have had those old solenoids die slow by working sometimes and even a little bump with something to fire them up and sometimes the button would stick in the on positon when I tried that, and I would have pull off a battery cable. Plus I heard the new repose have problems. I used the tr4 upgrade on the last one I restored; it has the button but not the older look. The car I am doing now I plan to use an old stock one I bought used; it would be nice to see some NOS solenoids pop up on eBay.
steve

Just throw your hand crank in the boot and You B awrite!

I never leave home without the crank. But in the meantime, in the process of cleaning and re-mounting, I discovered a ground loop coming out of the harness with a terminal that just happened to exactly reach the mounting screw. Attached with the clean and bright screw and what do you know, Bob's my uncle.
Thanks again to the members of this forum I'm on the road again (as Willie Nelson would sing)

Your description in post #8 indicates that the body of the solenoid is grounding to the car body only intermittently. Clean up the mating surfaces and tighten the bolts. The juice coming out of the small wire from the switch is activating coils to create electromagnetism and moves a plunger that makes contact between the big cable going from the batt and to the starter. The electromagnet won't work if the current it is getting doesn't go to ground.
Bob

Sorry. I didn't see your last post before writing this.

Crankshaft said:

I never leave home without the crank. But in the meantime, in the process of cleaning and re-mounting, I discovered a ground loop coming out of the harness with a terminal that just happened to exactly reach the mounting screw. Attached with the clean and bright screw and what do you know, Bob's my uncle.
Thanks again to the members of this forum I'm on the road again (as Willie Nelson would sing)

Click to expand...

So that's what that ground loop on my new harness is for. Makes sense now. I'm going to ground it at the solenoid base. Who knew.

karls59tr said:

So that's what that ground loop on my new harness is for... I'm going to ground it at the solenoid base...

Click to expand...

I am not sure what this 'loop' is that you mention, but there is a ground that connects just to the right of the control box.