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I need to finally replace my starter, the solenoid went bad a few months back, I hit it really hard with a hammer and it's been working for the time being. But it's starting to take longer to turn over, and its cranking oddly now, so I'm just gonna bite the bullet and do it this weekend. I had seen a writeup somewhere where they tore apart everything but the intake manifold, which is by far the biggest thing in the way. I figured it'd be easiest to just take off the manifold and replace the gaskets while I'm at it cause they probably needed replaced anyways. I already have the gaskets and the new starter unit on hand, just been putting it off for a while. But before I started to sink my teeth in, I wanted to see if anyone had any cautionary tales about anything I just talked about, because I'm a newbie to fixing cars and I don't want to bite off more than I can chew. Thank you!

Did this on my track car a few months ago and not starting by taking off the inlet was the stupidest thing I've done in a while. It is a set of S14 throttle bodies, but the principle is the same. Once I took that off it became an easy job, all for the effort of removing about 8 nuts.

I don't know if this is factory on all e21's, but some jerk ran the wiring harness through two of the fingers of the manifold, effectively locking it from being out of the way until I remove the harness. Ever since I found that out everything has gone downhill. I have to replace basically every hose I've come across, most are cracked in areas you couldn't see with the manifold on. One has what looks like solidified coolant in it. I have no clue and don't care much anymore, I just know theyre all getting replaced.
Anyways, can anyone take a look at their starter and tell me what electrical connections it has? Aside from the positive battery lead and one cable that went onto the same stud, I only recall one electrical plug that hooked on, but when I actually got the starter out, apparently there was another on the underside that my dad took out without taking a close look. And now I can only find one of those wires and have no clue which plug it goes to. I don't want to take a chance with where I plug it in at and fry my new starter
Pic attached are the three wires I know hook up. The main battery lead, the smaller red hookup that attaches to the same stud, and one mystery plug


This project turned into a nightmare real quick for a beginning mechanic, and the faster I can get all of this behind me and stop bumming rides to work and school, the better. Any help is dearly appreciated.

Big red is the 12v feed from the battery, permanent live so make sure you have the battery disconnected! Small red connects something else up, not sure but if it went on the terminal in the first place, that's where it belongs. The small black/yellow one is the starter solenoid wire that goes to the ignition switch, there are spade terminals on the top and bottom of the starter. If you connect to the top one nothing will happen, connect it to the one underneath that you can't easily see, and your starter will work. The top terminal appears not to do anything, and doesn't have anything connected. Or that's what I can remember from doing the one on the slug.

You sir are a gentleman and a scholar.
I got the starter all bolted in and wired up, hoses replaced (Whoever worked on this last felt it was ok to just use electrical tape on the vacuum hoses to stop the cracking rather than just replace them ), and I'm about to mount the intake back in. For the #1 cylinder, it has a unique gasket compared to the others with coolant running through it. Should I use gasket sealer around the portion of the gasket that has coolant? Or are the OEM gaskets made to handle that?

ALSO: What are the torque values for the inlet manifold for the m10? I found the exhaust manifold specs in the book but not the inlet. I found some specs on an e30 forum but I would imagine the only similarity would be the block, and not the intake, so that wouldn't transfer over.

Sorry to revive a old topic, but I'm not so sure the starter was my problem anymore.
Within the last week or so, the original problem I had associated with the solenoid is coming back. The car gets full electronics, and the battery is fine, but the car won't crank. Every other function is normal, but it just won't crank at all, no clicking, no nothing. I had originally assumed it was the solenoid because hitting it fixed it, but I think it was coincidence now. Last week I got the exact same problem. I assumed it was the solenoid again and I hit it with a hammer again but no dice. Within the time it took me to get a ride home and grab my multimeter to start troubleshooting, something changed because it fired up on my last ditch effort before I took the meter out of the bag. It was fine for a few days and it shat out on me again about 60 miles from home, I was near a bunch of mechanics and before I could get my hands into the car another one had his hands in there and swapped the spade terminal on the starter (yellow and black wire pictured above) to another terminal that results in the same electric connection, but was slightly tighter. Fired up. Went home and hoped to jesus the problem was just a loose connection. Fast forward to tonight and it happened yet again when I tried to start my car to get home from school. I had to get a ride before everyone left so I once again didn't get a chance to start looking at things. But if it's as intermittent as its been thus far, the car will fire right back up when I get back to school tomorrow and try.
I haven't gotten a chance to check the car itself, but I've been flipping through the wiring diagrams and it seems the only three things than can be the issue are the Ignition switch, the wire going from the switch to the solenoid, or the solenoid itself, which I doubt since it's new and still starts the car when it is working. I'm leaning towards bad wiring somewhere but the switch is still suspect. I'll update when I get more info

That would be my deduction as well. Believe there's no separate starter relay or fuse that can be messing things up? E21's are not really known for electrical gremlins (apart from having to roll your fuses every once in a while haha) so personally I wouldn't suspect wiring, I would put my money on the ignition switch.

Perhaps this (Dutch) thread can be of help. There's a small M3 screw that holds the electric switch in place.
http://www.bmwe21.net/forum/viewtopic.p ... 20&start=4

Battery might appear fine when measuring at idle/off but starting puts a HUGE drain on it. I had intermittent starting problems and was about to replace the motor when I realised the alternator had a poor earth. When it's running, get the car at 2000rpm+ and measure across the terminals. IIRC you should see >13.5v.

The problem appears to be bad grounds. I tried turning the engine over when I got to school and still wasn't getting anything. I pulled the negative battery cable at the battery side and reattatched it hoping a system reset would trick the car into working, and it was too smart for that. So after that I pulled the negative battery cable and scrubbed every terminal and connection point on the frame side it and it fired up. Faster than normal too! My bonding strip from the block to the frame is all frayed up too, so I'm going to replace that and I hope I'll see a lot of my gremlins go away!

I couldn't believe it was just a poor earth after all my head scratching too. Always nice when something is an easy fix.

Emphasis on it APPEARS to be bad grounds. The problem has gone away and come back before. It just seems the car really had it this time, so the fact that cleaning them brought it back to life has me hopeful. But at the end of the day I'm just riding on hope right now, haha

Fingers crossed!

I was mystified when my car wouldn't turn over properly but unsurprised when I realised I had forgotten to put the earth strap on the engine when I wired it all up. However ignition switches are known for going bad. My first E21 out in Oz did this and I used to jump the starter terminals with an old screwdriver the mechanic lent me until I fitted a start switch. Easy to do, you need to connect the big red permanent live wire in the ignition wiring to the black/yellow starter wire (from memory, can go and check wires on the slug if you need). I wired it up as an extra leaving the key functional at first but when the key stopped working altogether I disconnected it as a security measure - my switch looked like another rear demister one so theoretically casual thieves wouldn't press it.

So when you get a no start on the key, does it start if you jump the starter terminals??? If so it's the switch.

Other thing I have had is water in the fusebox.

Jim