Starter Solenoid, I have been through 4 and counting! Options

[ctc911ctc]

1974 2.0 - 24Kmiles
All stock

I received the car in late 2018, pulled from a garage in RI. Sat in the garage since 1986/88

The starter in the car was original. We removed near everything in the car, super cleaned and welded, put it all back together, and also bought a new starter. The new starter would not work right - clicked but no turn - so we put the original back in. Ran great.

Then the original started to fail (seemed like the copper wire from solenoid to motor had degenerated so we bought a 3rd. This one would not work so I returned it and got another. It worked great for a month and now this one clicks but the motor does not turn. Had to jump it with a screwdriver. Which though dangerous - works great!

At this point, over 2 years, I have 4 failed starters. One is 46 years old, the others are rebuilt (2) and new 1.

Which way would you go from here?

Another new OEM? (IMG:style_emoticons/default/blink.gif)
Another rebuilt???? (IMG:style_emoticons/default/barf.gif)
Put a relay in parallel with the Solenoid? (IMG:style_emoticons/default/smash.gif)
Get the super fancy Porche High Torque starter? (IMG:style_emoticons/default/first.gif)
Always park on a hill (facing downhill of course). (IMG:style_emoticons/default/lol-2.gif)

[bbrock]

Always park on a hill (facing downhill of course). (IMG:style_emoticons/default/lol-2.gif)

You laugh, but I did exactly that for almost a year when I was in college with my first beater 914. (IMG:style_emoticons/default/av-943.gif)

Watching this thread as I have a box of 3 old starters and need to decide what I'm going to put in my resto. (IMG:style_emoticons/default/popcorn[1].gif)

[dlee6204]

I'm going to guess your ignition switch is actually the problem and not the starter. I suggest replacing your ignition switch with OEM from Porsche (~$40) before going to the additional relay route.

I've had good experience getting rebuilt starters from my local FLAPS.

[michael7810]

I drove my car for almost 10 years on a rebuilt starter with no issues. Are you sure both battery cables and the trans ground strap at good? Cables can be severely corroded under the insulation. Ground points on the body can be corroded. Is the ignition switch and associated wiring good? Maybe try installing a ford solenoid if not sure about the ignition switch and wiring. Just some other things to check as I don’t think this is a common problem

[Superhawk996]

(IMG:style_emoticons/default/agree.gif) with the two posts above.

Your chance of having 4 bad starters in a row over 2 years is terribly small.

You absolutely need a ZERO ohm connection between the body and the engine/transmission. Also if you have grease and/or corrosion between the starter and the transmission that won't help a bit.

Verify ground 1st before anything else.

If jumpering it with the screwdriver works, then focus 2nd on the Ignition switch and the wiring from the switch to the solenoid.

All the description to me sounds like bad grounds and/or too much voltage drop to the solenoid that is hovering right on the edge of working or not working. Like post above I drove my 1st teener for about 10 years on same starter. When ever I had a problem it was usually a corroded ground. One and only one time, I had the igntion switch start getting flaky and replaced it immediately.

Starters are easily tested with a good battery, jumper cables, and a piece of 10 gauge wire to hit the solenoid terminal with. Much easier to test them on the bench than in the car!

[AZBanks]

I would suggest giving Mark Henry's fix a try.

http://www.914world.com/bbs2/index.php?sho...amp;mode=linear

[ctc911ctc]

I installed a bypass switch for this purpose. The ignition switch is working correctly.

The switch and the bypass switch both click the solenoid but do not engage the starter........almost as if the cross-bar in the solenoid is not touching the terminals.

I'm going to guess your ignition switch is actually the problem and not the starter. I suggest replacing your ignition switch with OEM from Porsche (~$40) before going to the additional relay route.

I've had good experience getting rebuilt starters from my local FLAPS.

[Superhawk996]

I would suggest giving Mark Henry's fix a try.

http://www.914world.com/bbs2/index.php?sho...amp;mode=linear

Mark's fix is great and has an intended purpose. It will not address bad ground connection or a flaky swith.

I'm going to pull quote from Mark's fix:
"Of course as with any electrical trouble shooting the first order of business is always clean all of your grounds and make sure the chassis to transmission ground strap is in place and in good condition."

No offense to AZBanks but this isn't a guessing game. Trouble shooting electrical issues requires a methodical approach before adding more variables and more wiring.

[Superhawk996]

I installed a bypass switch for this purpose. The ignition switch is working correctly.

The switch and the bypass switch both click the solenoid but do not engage the starter........almost as if the cross-bar in the solenoid is not touching the terminals.

Nope. Going to make alternate suggestion.

As if you don't have a good ground and the starter motor can't draw the large current it craves.

OR that you're dropping so much voltage on the way to the solenoid that it can't fully pull in. This one can also be related to ground circuit not allowing solenoid to pull enough current.

When you say you've installed a bypass switch? What do you mean by that? Where is it wired to / from? With what gauge wire?

[ctc911ctc]

Being a SuperHawk fan, I am going to tread very lightly.

The bypass (will get a picture later) is a bypass of the ignition switch. I used 12 gauge stranded wire with Soldered blade connectors. It is installed on the YELLOWish wire -actually the blade next to it on the solenoid - that signals the Solenoid from the ignition switch. The other side is the connection to the battery wire at the Solenoid. I installed this for other troubleshooting. Pretty Handy!

Though the ground is an interesting thought, I have measured the voltage against the engine (ground) of the start signal and get a solid twelve when the key is not turned and about 9v when the key (or switch is activated). A solid BUMP noise is heard within the starter/solenoid but no motor activity. This is when I get under the car with my son ( the one that likes me the most - for obvious reasons) and cross the two Solenoid terminals with a hearty screwdriver.

So with all of this information, I am centering on the solenoid - but will double check the ground wire at the battery into the wall of the car. Pretty sure that is all clean and tight. however,.,,,,,,,,,,,,, (IMG:style_emoticons/default/wacko.gif)

Thank you Superhawk!

I installed a bypass switch for this purpose. The ignition switch is working correctly.

The switch and the bypass switch both click the solenoid but do not engage the starter........almost as if the cross-bar in the solenoid is not touching the terminals.

Nope. Going to make alternate suggestion.

As if you don't have a good ground and the starter motor can't draw the large current it craves.

OR that you're dropping so much voltage on the way to the solenoid that it can't fully pull in. This one can also be related to ground circuit not allowing solenoid to pull enough current.

When you say you've installed a bypass switch? What do you mean by that? Where is it wired to / from? With what gauge wire?

[GeorgeRud]

Clean and verify the grounds, then attach a jumper switch from the starter terminal to the solenoid. If it works well, the issue is in your wiring, not the starter in my opinion. Using a relay to take the load off the yellow wire is a good idea with 40+ year old wiring.

[Superhawk996]

OK. Like the troubleshooting aspect of the bypass switch.

12 Gauge wire is a bit small. 12 gauge wire generally OK for 20 Amps. Not sure what the solenoid draws, but, I'll grant that it isn't 20 amps. Plus the length isn't very far - just from B+ to the solenoid. Does this bypass switch work or do you get the same bump/clunk noise but no starter motor & engine rotation? I think from previous post you impled it doesn't work until you completely short from B+ to the starter motor winding terminal (i.e. bypassing the solenoid completely). Does this work every time?

Now here is where it gets interesting. So you have 12v with no load (open circuit). Good.

When you attempt crank you're saying you're dropping to 9 volts. That is a lot of sustained voltage drop! Battery should support continued cranking and not drop to 9 volts continious. Are you sure you've got a good battery?

I just tested two good alternators on bench and I get a 9.75 volt only momentarily when the motor is experiencing a large inrush current. After that it's more like 10.5 volts as the starter motor is runing at free speed.

The sum of voltage drops around a series circuit has to equal the potential across the battery. (Kirchhoff's Voltage Law).

So in my case what we are saying is the motor is dropping 10.5 volts as it runs. (measured from B+ starter termnal to ground). Where is the other 1.5 volts dropped? In the wiring (crappy jumper cables in my case).

The starter motor windings measure 0.1 ohm or slighly less (resolution of my DMM limited) on both starters. How much current are we drawing at inrush? If voltage = 9.75 then by Ohms law we are drawing 9.75 volts/.1 ohm = 97.5 amps at inital motor start (in rush). Not unplausible.

So now back to your problem. Where is your other 3 volts going?

Possibilities:
1) Wiring drop. Still the most likely cause. Ohms law Voltage = current x resistance. More resistance with same current draw = higher voltage drop. If you wiring were running 2x the resistance of my jumper cables that would lead to a 3 volt drop. Now we're back to poor grounds or high resitance wiring adding restance.

If you have a bad ground at body to transmission or battery to body and are trying to draw 100 amps of inrush current we only need 0.03 ohms of resistance to drop 3 volts in your wiring. You need a ZERO ohm battery ground to body ground connection and a ZERO ohm Body to engine ground. When you're potentially drawing hundreds of amps, it doesn't take much resistance to add up to a big voltage drop in the wiring.

Also make sure that you have a clean connection between the motor side wire (other terminal on the solenoid) and that the nut is tight and clean.

2) Starter motor loading is way higher (drawing more current at stall - i.e. can't rotate the engine for some reason). High compression motor that stock starter cant turn? You don't mention this so I'm going to assume this isn't the issue.

Quick check -- if you push / bump the car while in gear and get the current cylinder past top dead center does it then spin the starter motor until the next piston tries to get to TDC on your next starting attempt?

3) Battery is weak and can't support voltage and current under load.

Hope some of this sheds light on why grounds are such a big deal. Good luck! Here to help if I can.

P.S. As I'm thinking about your 3v drop -- I keep referring to ground but you also need a ZERO ohm connection between Battery positive and the B+ terminal on the starter solenoid.

[porschetub]

I would suggest giving Mark Henry's fix a try.

http://www.914world.com/bbs2/index.php?sho...amp;mode=linear

Starter solenoids are super basic,a wound coil that gets power from the key on start and repels a steel piston forward that moves an arm to move the bendix to engagement of the pinion gear to flywheel.
Starting function off on the key with engine running the piston returns back due to no coil power due to it being spring loaded .
I used to rebuild Bosch starters and very rarely found bad solenoid,most just needed a clean cause they were gummed up with old grease.
Best to take your starter to a Bosch shop and get it done right,I have a strong mistrust of "so called" rebuilt units....paint looks nice on them (IMG:style_emoticons/default/av-943.gif) (IMG:style_emoticons/default/av-943.gif) .
Other things have been already mentioned, (IMG:style_emoticons/default/beer.gif) .

[fixer34]

Now that we beat the electrical issues to death, what about mechanical interference? As mentioned, it seems there is a good clunk when the solenoid engages, but the starter never turns. The pinion drive has to extend all the way for the crossbar to make contact and spin the motor. Is it possible there is something inside the housing or on the flywheel that is jamming the pinion? Should be able to pull the starter and look inside while someone turns the engine over by hand.

[Superhawk996]

I would suggest giving Mark Henry's fix a try.

http://www.914world.com/bbs2/index.php?sho...amp;mode=linear

Starter solenoids are super basic,a wound coil that gets power from the key on start and repels a steel piston forward that moves an arm to move the bendix to engagement of the pinion gear to flywheel.
Starting function off on the key with engine running the piston returns back due to no coil power due to it being spring loaded .
I used to rebuild Bosch starters and very rarely found bad solenoid,most just needed a clean cause they were gummed up with old grease.
Best to take your starter to a Bosch shop and get it done right,I have a strong mistrust of "so called" rebuilt units....paint looks nice on them (IMG:style_emoticons/default/av-943.gif) (IMG:style_emoticons/default/av-943.gif) .
Other things have been already mentioned, (IMG:style_emoticons/default/beer.gif) .

(IMG:style_emoticons/default/agree.gif)

However, you do need sufficent voltage and current to induce the magnetic field and get that solenoid to pull in.

I'm almost wondering if your ignition (yellow line from ignition switch) is so high resistance that it has been not getting a good clean pull in of the solenoid. Over time, maybe this is causing arching between the solenoid terminals and the pull in connection bar & eroding and resulting in high resistance there as you suggest. This would be plausible if you're jumpering from B+ of the solenoid to the starter motor winding terminal works every time but the your bypass switch from B+ to the solenoid control will not.

Hard to believe this has happend three times in two years though!

[davep]

I have measured the voltage against the engine (ground) of the start signal and get a solid twelve when the key is not turned and about 9v when the key (or switch is activated). A solid BUMP noise is heard within the starter/solenoid but no motor activity. This is when I get under the car with my son ( the one that likes me the most - for obvious reasons) and cross the two Solenoid terminals with a hearty screwdriver.

What is the voltage across the battery terminals when the ignition is off?
What is the voltage across the battery terminals when the ignition is on?
What is the voltage across the battery terminals when starting?
When off it should be a minimum of 12.8 going up into the low 13 range.
Should not change much just turning ignition on.
Will drop into the 8 to 9 range when cranking.

Does it start when jumping the two Solenoid terminals? If so, then the problem is most likely electrical, and may be bad grounding; transmission strap and battery to engine wall cable. I fixed one car by putting a ground cable from battery post to the fan shroud; an 8mm hole not used near the coil location.

[JOEPROPER]

FWIW, I replaced my old starter (high amp draw) with a reman from Worldpac and it starts great most of the time. Sometimes the bendix doesn't kick out, so I know this starter is defective and will need to be replaced.
I've seen new starters in a new box bad. I think you need to do you're electrical checks first, but keep in mind that just because it's new, doesn't mean it's good.

[ctc911ctc]

*******UPDATE*******

The original Starter has a tired solenoid - took it apart and the crossbar was burnt out.

The second one I got had a cracked mounting ear ( where the long bolt is threaded through), I took it back for the 3rd one.

The third had a stuck extension gear, the solenoid was fine. (More about this later)

The fourth (bought on Amazon) had the solenoid stuck and the jumper wire from the solenoid to the starter burned through when I turned the key - had to disconnect the battery.

I then rebuilt the solenoid from the 3rd and the starter motor from the third (stuck extension system) and it works fine. The extension system needed grease. The solenoid needed the plastic spacer to be milled down to a thinner spacer so it would allow the crossbar to reliably engage. The plastic spacer, (in between the two halves of the solenoid), had burrs and other excess 'plastic-flash' that I removed.

The forth I bought on Amazon and was able to return it to the checkout counter at WholeFoods...........what an un-natural act......

Car is starting reliably, fun to drive and there are still 100 'little' projects.......sigh

[Superhawk996]

(IMG:style_emoticons/default/first.gif) for perseverance.

Hard to believe you've had such a bad run of parts. I honestly would have bet money on pure electrical issue.

Hopefully that is behind you now.

[Cairo94507]

Great job working the problem and resolving it. Also, thanks for letting us all know the resolution. (IMG:style_emoticons/default/beerchug.gif)