No Crank Issue

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Sbeaud
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No Crank Issue

Post by Sbeaud »

Hoping for some guidance.

Situation: Drove to the store a few miles from home yesterday (on my way to a BMW club drive...) and when I tried to leave no crank. Push started the car to get it home (started immediately with very little pushing). Same problem today in the garage - not an intermittent issue.

All electrics seem to work normal with key in on position
Battery is ~2 years old

Using the diagnostic connector if I check the voltage at pin 11:
Key off 0 volts
Key on it reads about 0.5 volts
When the key is moved to start position it jumps to 12 volts for an instant then drops back down to 0.5 volts.

I've looked through a number of threads and would like to confirm my understanding. Using the diagnostic connector if I jump between 1 and 11 with the key in the on position the starter should crank, yes? It does not, but there is some sound coming from the top of the engine (something with the fuel system?)

Is it a possible bad starter?

Thanks
Scott
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1988 BMW US M6 Diagnostic Connector.JPG
1988 BMW US M6 Diagnostic Connector.JPG (124.04 KiB) Viewed 8389 times
1988 M6
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sansouci
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Re: No Crank Issue

Post by sansouci »

I just replaced the starter switch (bought OEM BMW from dealer for about $80). It goes on the steering column just behind the ignition switch. The tamperproof bolt is designed to shear off if turned and you will likely have to drill it out, Replace it with a hex bolt. When you open up the column, you should be able to start the car by jumping the contacts. These things do fail as they are only friction contacts.
Best of luck,
Ken
Sansouci
84 E24 633Csi Auto, Bronzit/PearlBeige 6997510
93 E32 740il M60 Auto, Alpenweis/Ultramarine
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daz635
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Re: No Crank Issue

Post by daz635 »

I have always thought it was pin 11 and pin 14 that were jumped to spin the starter. I have the M30 motor can someone confirm S38 is the same, I thought it was going by the wiring diagrams

Pin 14 is hot all the time as it comes from the battery. So jumping pins 11 and 14 spins the starter even with the ignition off. With ignition on the car should start with this method. Using this method bypasses any issues with your ignition switch, relays or wiring.

If the starter spins and the car starts with the ignition on then I would be looking at ignition switch, relays or a wiring if the starter does not spin I would be looking at the starter motor/ solenoid

The starters on these cars are very sensitive to voltage. Even a small drop can cause them not to function. Check you battery terminals are tight also check the all connections on the starter itself are clean and tight. Also check the voltage at the starter
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sansouci
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Re: No Crank Issue

Post by sansouci »

My mechanic jumped the connectors at the starter switch to get it started.
Ocam's law: start with the simple solution first. Battery voltage is easily checked. Move on from there.
Best of luck.
Ken
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84 E24 633Csi Auto, Bronzit/PearlBeige 6997510
93 E32 740il M60 Auto, Alpenweis/Ultramarine
60 528i M30 5-speed Green/Beige (crushed)
71 240Z 4-speed White/Blue (rusty & sold)
65 396 Chevelle 4-speed, Marina Blue/Black (stolen)
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Sbeaud
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Re: No Crank Issue

Post by Sbeaud »

Thanks for the feedback.

Daz635 - yes, the non M6 diagnostic connector has a different layout with a power-only lead (#14). See below.
Ken - thanks for the info. I think I remember a thread (maybe yours?) about this replacement. I think if I can get 12 volts to pin 11 of the connector that should bypass the switch. I didn't have a good 12v source nearby (battery's in the trunk), so I cheated and used pin 1. But Daz635's point of sensitivity to voltage I may have to rig up a jumper from a better source (battery?).

I think if a straight jump to pin 11 with good voltage (maybe I'll jump the vehicle from another car at the same time) to pin 14 should pinpoint the starter?
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1988 BMW US non-M6 Diagnostic Connector.JPG
1988 BMW US non-M6 Diagnostic Connector.JPG (159.78 KiB) Viewed 8346 times
1988 BMW US M6 Start Circuits.JPG
1988 BMW US M6 Start Circuits.JPG (153.37 KiB) Viewed 8346 times
1988 M6
daz635
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Re: No Crank Issue

Post by daz635 »

Thanks for the clarification re M30 vs S38 always good to learn something new

Using a good external 12volt source to pin 11 looks like the go. Having the battery in the trunk is a bit of a pain

Let us know how you go
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RossDinan6
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Re: No Crank Issue

Post by RossDinan6 »

It would be worth checking the start signal wire at the starter. It is a spade connector as I recall. They loosen up with time due to vibration. It could be as simple as a loose connection. Check voltage at the start signal wire while cranking as well, you may not be getting voltage to the solenoid. As stated above, if it cranks from the diagnostic connector, 11-14, your starter solenoid is most likely the problem.
Ross
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Sbeaud
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Re: No Crank Issue

Post by Sbeaud »

Thanks very much for the suggestion. I have not had time to get to the car yet. I'm also thinking starter access on the S38 may not be easy...
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Sbeaud
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Re: No Crank Issue

Post by Sbeaud »

Had some time and the weather warmed up so...

Checked voltage at starter (10R wire) - 12.5V
Key on
BK/GR: 0V
BK/YL: 0.5V

Key Start
BK/GR: 11.4V
BK/YL: 11.4V

Using a screwdriver and jumping BK/YL to the 10R wire no sound from the starter/solenoid. But it does sound like the fuel pump turns on from the rear of the vehicle?

I'm thinking solenoid? Or is the 11.4V inadequate?

Thanks

Scott
Attachments
1988 BMW US M6 Starter Tests.JPG
1988 BMW US M6 Starter Tests.JPG (113.89 KiB) Viewed 8257 times
1988 BMW US M6 Starter-Solenoid Wiring.JPG
1988 BMW US M6 Starter-Solenoid Wiring.JPG (49.57 KiB) Viewed 8257 times
1988 M6
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RossDinan6
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Re: No Crank Issue

Post by RossDinan6 »

Jumping red to bk/y is the same as turning the key to the crank position. The 11.4v is a bit low, but I expect the car would start. Pull the starter and have it checked. I decent starter/alternator shop can probably go through it for you for a reasonable amount.
Ross
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Sbeaud
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Re: No Crank Issue

Post by Sbeaud »

Thanks. I'll get started pulling the starter...
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Re: No Crank Issue

Post by Sbeaud »

Well, not so easy to pull the starter...

1. Remove the intake - could not get the crankcase vent hose loose. Stood on the strut tower and the valve cover and pulled it off.
2. The inboard starter bolt takes a special box end wrench - a friend welded up a copy. Actually broke it breaking the bolt loose.
3. The outboard starter bolt was too tight for my aging arms to loosen with an open end wrench. So I ground down a socket to barely fit - after hours of grind and check I finally broke it loose.
4. Take the starter to the parts store for them to check. They say it's OK...

So...

Are the auto parts store checks the last word in verifying a functioning starter? This was a real pain to get out and I'm not interested in installing a potentially bad starter/solenoid.

Sticky hose:
1988 BMW M6 Intake.JPG
1988 BMW M6 Intake.JPG (118.28 KiB) Viewed 8215 times
Inboard starter bolt.
1988 BMW M6 Starter Inboard Bolt - 1.JPG
1988 BMW M6 Starter Inboard Bolt - 1.JPG (198.88 KiB) Viewed 8215 times
1988 BMW M6 Starter Inboard Bolt.JPG
1988 BMW M6 Starter Inboard Bolt.JPG (103.91 KiB) Viewed 8215 times
1988 BMW M6 Starter Inboard Bolt Removal Wrench.JPG
1988 BMW M6 Starter Inboard Bolt Removal Wrench.JPG (189.31 KiB) Viewed 8215 times
Outboard starter bolt - accessible with open end or heavily modified socket.
1988 BMW M6 Starter Inboard Bolt Removal Wrench.JPG
1988 BMW M6 Starter Inboard Bolt Removal Wrench.JPG (189.31 KiB) Viewed 8215 times
Thanks

Scott
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RossDinan6
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Re: No Crank Issue

Post by RossDinan6 »

Holy crap that sounds like an ordeal. I had no idea an M was that complicated. On my M30 it will come off with the right combo of socket and extensions. Still a PITA though.

Everything you have done points to the starter. I can't understand how the parts house got it to run. I studied your ETM again, as well as mine, though different there is nothing I saw to change my thoughts on this. Do you have a pair of jumper cables? Put them on and jump the solenoid to the power stud and check for yourself. Just be sure to have a hand of foot on the starter when you do. The starting torque will make the starter jump (If in fact they were right)
Ross
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Sbeaud
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Re: No Crank Issue

Post by Sbeaud »

Thanks - I was thinking about trying that.
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Sbeaud
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Re: No Crank Issue

Post by Sbeaud »

Just noticed my last image was incorrect.

Here's the outboard bolt.
1988 BMW M6 Starter Outboard Bolt.JPG
1988 BMW M6 Starter Outboard Bolt.JPG (108.51 KiB) Viewed 8197 times

And the modified socket.
1988 BMW M6 Starter Bolt Removal Socket - 1.JPG
1988 BMW M6 Starter Bolt Removal Socket - 1.JPG (96.12 KiB) Viewed 8197 times
Also, while the intake airbox is out I'd like to clean it up. Any thoughts on a good readily available cleanser that won't damage the surface?
1988 BMW M6 Intake.JPG
1988 BMW M6 Intake.JPG (118.28 KiB) Viewed 8197 times
Thanks
Scott
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Sbeaud
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Re: No Crank Issue

Post by Sbeaud »

So, used jumper cables on the starter and it worked fine. Reinstalled in the car and it starts. So I believe it is an intermittent solenoid/starter issue. New starter on the way.

Thanks!

Scott
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hornhospital
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Re: No Crank Issue

Post by hornhospital »

Just a suggestion, but on my 84 633 no matter how clean I got the joint between the starter and bellhousing, the starts were intermittent and seem to drag even with a fully charged battery. Out of curiosity I ran a separate ground cable from the battery negative to the outboard starter bolt. Bingo, no more starting problems.
Ken Kanne
'84 633CSi "Sylvia"; '85 635CSi "Katja";'85 325e "Hazel Ann"; '95 M3 "Ashlyn"
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Sbeaud
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Re: No Crank Issue

Post by Sbeaud »

Thanks for the tip - I'll clean the terminals before bolting it up. But...

Overnighted the starter from FCP Euro in order to install it during warm weather and some time off (70+ degrees F in Detroit in the middle of November?). But the solenoid on the starter they sent has one less terminal.
1988 US BMW M6 Starter-Solenoid from FCP Euro.JPG
1988 US BMW M6 Starter-Solenoid from FCP Euro.JPG (129.41 KiB) Viewed 8143 times
The missing terminal is for the Bk/Gn wire from the unloader relays. Is the expectation that the Bk/Gn wire would be put on the same terminal as the start circuit Bk/Yl?

So I'll have to wait until tomorrow to speak with FCP Euro.

Scott
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RossDinan6
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Re: No Crank Issue

Post by RossDinan6 »

It is a little unclear to me their reasoning for the bk/gn wire in your case. My 84 has that terminal unused and energizes the unloader relay on start signal.

I would have to compare the two ETMS to get a better idea.

Perhaps it is some of Germany's finest unfathomable engineering. I have scratched my head on my car a number of times in the last two decades. Or maybe someone can enlighten me.
Ross
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86_6series
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Re: No Crank Issue

Post by 86_6series »

In the past I've installed 5 starters in 32 years. The ongoing problem was always the solenoid.
It gets gummed up and with the slightest drop in battery voltage the magnet won't be strong
enough to pull the piston into the flywheel. i don't think they rebuid the solenoids.

The final Bosch remaned starter had a used solenoid that I replaced with a new one.

That was about 7 years ago. even sometimes when the battery is not at it's best level--
never had an issue spinning and engaging the flywheel.

Just an FYI.

Bob V
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Sbeaud
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Re: No Crank Issue

Post by Sbeaud »

FCP Euro is overnighting another starter.

Bob - I was thinking the solenoid might be the issue, but a quick search showed the solenoid alone was more expensive than a reman starter. I assume the solenoid would be reman as well. Hope this one does the job.

I don't have a 1984 electrical manual, but the 1988 for a non-M6 shows the same unloader circuit. Not sure I understand the circuit either...

Thanks!

Scott
1988 M6
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Re: No Crank Issue

Post by marc79euro645 »

I use allen head bolts with washers, on the starter. Cut a long allen wrench and use it with socket and extension.I also ground a slight groove around the allen wrench head, to allow some wobble. (Like wobble allens you can buy.)
it's still not fun.
good luck
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RossDinan6
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Re: No Crank Issue

Post by RossDinan6 »

Sounds like a ball end socket to me. They work great.

Have a close look at the start signal wire/terminal. The 11.4v mentioned earlier while low, should be fine. But....... Make sure the terminal is clean and shiny before making the connection. Wire brush the stud as well. If there is any doubt at all, replace the ring terminal. Corrosion can blacken the wire causing resistance and thus voltage drop.
Ross
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Sbeaud
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Re: No Crank Issue

Post by Sbeaud »

Starter showed up - looks correct!
1988 US BMW M6 Starter-Solenoids from FCP Euro.JPG
1988 US BMW M6 Starter-Solenoids from FCP Euro.JPG (148.63 KiB) Viewed 8084 times
Also bought a set of S-wrenches from Harbor Freight to see if they would work - they do!
S Wrench for starter.JPG
S Wrench for starter.JPG (238.27 KiB) Viewed 8084 times
I'll be cleaning the terminals before installation!

Scott
1988 M6
emac
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Re: No Crank Issue

Post by emac »

How did the new starter work out?
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