Another Starter Wiring Question

[Guest Anonymous]

Hello!

I have a bum starter. Solenoid clicks/engages the bendix drive but she won't spin. Never gave me any reason to complain and worked just fine until I parked in a dark underground garage. Turned the key and buzz of the pump click of the solenoid. Unable to push start it considering the incline. So after 20+ years its time for another starter. A friend had traded me some parts off of his E30 and I thought I was prepared to throw the smaller/lighter and maybe more desirable on the old girl.

Unfortunately, while there were four (4) posts on the old starter, the smaller starter has only three (3) posts. As far as I can tell maybe this newer-smaller starter does not have a provision for the coil bypass (red/black wire?) The following pics of similar starters may better explain the situation.

Should I wait till I can locate a 4 terminal solenoid or is there an easy workaround? The manual is of no help since this is an upgrade beyond the scope of the manual. Yes, I have looked at the archives and I have seen emeyers and esty's pics, but they all have 4 posts - not three.

Any help would be appreciated!

[penth2o]

Hi.

Why not rebuild the original?

[Guest Anonymous]

Hi.

Why not rebuild the original?

Since I have what seems like a lightly used starter, I 'd prefer using it. Time is of the essence since I am taking someone else's parking place. If I could pop the new smaller starter in I would be ahead of the game. Plus, it is easier to access the retaining bolts with the smaller starter.

The current starter is out of a 6cyl and was previously rebuilt. New brushes and bearings are not as easy to locate as they once were and I suspect the commutator is worn. The bendix gear is pretty worn too. If I had to I probably could scrounge up another M30 starter, but I would prefer not having to hunt through storage for it.

thanks.

[Guest Anonymous]

I jumped the gun in describing my three terminal solenoid as being unique given that Bill Williams' posted pictures of his "three" terminal connection too. This leaves unresolved what to do about the missing "15" terminal?

Bill's post is here and Curt I. summed things up.

http://www.bmw2002faq.com/component/option,com_forum/Itemid,57/page,viewtopic/t,318338/

"(Assuming you're working on a '72 car) In addition to the battery and ground connections, you need one more wire to the starter motor. The wire you describe as "from the ignition" is black and should connect from terminal 50 on the ignition switch to terminal 50 on the starter. Although this comes from the ignition switch, it is the "start" circuit. Hook that up, and you're set. Remember, any terminal in the car labeled 50 is the start circuit.

Your new starter motor might have a second small terminal that is not in view in your photo. You can see both small terminals in Earl Meyer's pic. This second small terminal is number 15, and you do not need to make a connection to it in your '72. Circuit 15 is "Igniion", i.e., power for the ignition system. In the later 02s that use resistance wire instead of a ballast resistor, terminal 15 on the starter bypasses the resistance wire during cranking to provide full battery voltage to the ignition coil. In those cars there should be a wire from terminal 15 on the starter to terminal 15 on the coil. That is the 'cold start' stuff Chris is describing.

If you look closely at the starter, you might see the labels 15 and 50 next to the two small studs."

On my starter the only marking on the solenoid is "50" and the placement of the ignition wire is clear. But what about the "15" can it be connected to the 50? Otherwise where would it go? I hate to say this, but on the old starter, leaving that smaller 15 spade disconnected was a sure way to prevent the car from starting. So I suspect that if I bolt everything back up without the 15 connected I will not be able to start the car or keep it running. (I noticed once that the engine would stall with the wire disconnected. It may be a ballast bypass, but on my car (72-73 tii) it seems to be essential to continued running. Incidentally, I am running a red coil with a ballast resistor.

So - what do I do about the absence of a 15 terminal? Thanks in advance.

[ingraham]

Looks like you understand what's going on. But I'm puzzled by the behavior you describe. Normally, Terminal 15 on the starter supplies battery voltage to the ignition coil *during cranking* only. After starting, coil power comes from the ignition switch (also Terminal 15).

What's puzzling is your statement that removing the wire from starter Terminal 15 makes the running engine stall. Normally, I would expect the following behavior with starter Terminal 15 disconnected: during starting, the engine should be slower to fire, as the coil is receiving a lower voltage, and a longer cranking time should be needed. During running (after starting), removing the 15 wire from the starter should have absolutely no effect on the engine.

Unless you have some strange rewiring of the ignition or starter, you should be fine if you tape up the wire that went to starter Terminal 15. That should get you out of the garage and back home, where you could do a permanent fix.

As a permanent fix, you could install a ballast bypass relay in the same was as the original. That is the best solution if you want to use the E30 starter motor that lacks a Terminal 15.

[Guest Anonymous]

Looks like you understand what's going on. But I'm puzzled by the behavior you describe.

Unless you have some strange rewiring of the ignition or starter, you should be fine if you tape up the wire that went to starter Terminal 15. That should get you out of the garage and back home, where you could do a permanent fix.

As a permanent fix, you could install a ballast bypass relay in the same was as the original. That is the best solution if you want to use the E30 starter motor that lacks a Terminal 15.

Thank you for your reply. To the best of my knowledge the wiring is all original. What you say makes sense but I had the same thing happen with a bavaria and an e9. For years I used to park the 02 at the airport and would pull that wire. I know it would work because I would forget to reinstall the wire and would not be able to start the car until I remembered the wire.

Since my last post I pulled the original starter and tried to test it with a pair of jumper cables and some test leads. Bendix drive would engage and gear would rotate .5 inch and stop. I tried this with the new small starter and I had the same results except the gear would rotate a little further. This worried me that both starters were kaput so I went to storage and grabbed another grease covered super-heavy starter.

When I returned to the car I was told to move so I did not even try bench testing it. I installed it and couldn't get the starter to move. I checked the battery and it read 12.75V at rest so I assume the battery was not the problem. Then I went to the ignition switch and figured it was too worn and maybe the contacts were loose, corroded or plain worn. Swapping the switch for another made no difference.

Finally, I asked the fella waiting on me for a jump start. The starter labored and she started! I pulled out of the garage and left it running and grabbed my VOM and tested the voltage at the battery now it read 14v indicating the charging system is a-ok.

If you have read this far, can someone please answer a few simple battery questions?

1. I do not have an ammeter handy. Since the gel battery is holding a steady charge (12.79v) (2 years old) does it make sense that it can't provide decent cold cranking amperage? It gave no warning that it was in bad shape.

2. I wondered about my cables (which look new and shiny). Since I am getting 14v at the battery when the engine is running, it seems that the cables are not an issue? Right? No cables were moved when we jump started the car So, I would assume if the cables were bad from the battery to the starter they would still be bad even if I used another battery.

3. Is there anything else that should be checked?

Since the initial post involved the wiring to the starter I may repost the final portion of this thread since I really could use an answer.

Many thanks for those who read this far!

[Guest Anonymous]

As a permanent fix, you could install a ballast bypass relay in the same was as the original. That is the best solution if you want to use the E30 starter motor that lacks a Terminal 15.

Forgive me for being dense. You are undoubtedly more familiar with the E30 electrical system than I am. Are you suggesting harvest a bypass relay from an E30? If so, exactly where is it on the car and what does it look like? I would bet several people who plan to upgrade their starters may find your answer most valuable in the future!

Thanks!!