Ignition switch issue - starter fails occasionally

[nmlss2006]

I love E38s... I love E38s... paraphrasing a well-known Roundel columnist...

So the 740 now tracks straight. Oh, and it uses less gas. Quite a bit less gas - 6-8%.

This is good.

However, it has developed an interesting habit: very rarely, say once a week, the starter doesn't engage.

This is not good.

AFAIK this is what the circuit looks like:

https://www.newtis.info/tisv2/a/en/e...ontrol/bQzWWzx

Reading around, it sounds like the most likely culprit is the ignition switch itself, but I will take any suggestions. The issue is, it's sporadic now but I'd really rather not get a delighted WA / phonecall from my SO.

This makes it difficult to diagnose and somewhat urgent at the same time.

I love E38s... I love E38s...

[RIboater2]

are you sure it's not the starter itself going? would mimic the same symptoms. Had to replace mine a year ago.

[sealbeach740]

When my iggy switch went bad, I could turn the key on & then back off & repeat 5, 6, 7... times until it would turn over like nothing was wrong.
Then, the next time it might start on the first try, or the 5th.
Point is, for me, it would always end up starting.
The sliding passenger side sun visor mirror cover didn't show any abnormalities.
But, replacing the iggy switch fixed my particular problem.
YMMV.

[nmlss2006]

RIboater (sail or power?), you are entirely correct. It could be the solenoid on the motor itself, it might even be the relais.

But I've been reading around (yes, I do that before asking a question) and there seems to be a majority vote for the ignition switch as the most likely culprit, especially on cars that have lived a good life.

SB, my symptoms are nowhere near that bad yet, but after a try or two it always starts. And keeps going (so far) for weeks.

[sealbeach740]

If this helps, when my iggy switch went bad, I did not hear a relay or a "click" when I turned the key to try to start the 7.
But, the dashboard did light up.

[nmlss2006]

Huh. Right, that would make sense, because of course neither the relais nor the solenoid would click. I'll have to listen for it the next time it happens. Thanks!

[racer2086]

90% of the time in all my cars (not just BMWs), when that happens, the starter is getting worn. It's either brushes or something else. The solenoid, like you said, is a possibility, but if you bump the starter and it starts, then it's likely the starter itself.

Of course, the ignition switch is easy and cheap, so may be worth a shot first, but your starter may be nearing time for a rebuild.

[nmlss2006]

racer, agreed, but when this happens I don't even get a little spin or the classic click of the solenoid, so I doubt it's going to be brushes... I suppose in any case taking the starter out, cleaning it and replacing the brushes won't hurt, right?

How bad is taking the starter out in an E38? This appears to be the way: http://www.bimmerboard.com/forums/posts/403220

It has the feel of something delightful, I can tell already.

Now I have to decide whether to do this before it gets worse to prevent a nasty phone call from my SO.

[RIboater2]

A lot easier getting the starter out of the V8 than the V12 from looking at that link. You can even SEE it! lol You have to pull the exhaust system down on the V12 like a Chinese puzzle and still have limited access. Ask me how I know.. lol Have a post about it some time back. Maybe under RIboater. riboater2 is because i got locked out of my original account from 2005. thanks mods
If it's that accessible I'd still give it a bang with a hammer next time before trying the key 10 times. At least you'll know and won't be chasing ghosts. They may be different but my 750 had symptoms like you're describing as mentioned earlier and it was the starter. It came on gradually literally for years. At some instances putting it on a 50amp charge to start was enough to get it to kick until it just stopped working. Had it towed home and when I could get access to the starter, hit it with a pipe and started right up, so that was that.

[racer2086]

You won't get any spin if those brushes are making contact. It's just an open circuit at that point. The solenoid is on these starters, right? I don't think you'd hear the click like in my 85 Mustang where the solenoid is right on the fender next to the hood. RIboater2 is right...take a hammer next time and give it a whap. It may just work after and give you a diagnosis right there.

[nmlss2006]

Yes - if the brushes in the motor assembly don't make contact, you won't get any spin. However, the solenoid will click - if it doesn't, you don't get any voltage at the brushes to start with...

It's actually pretty audible, try with a car that has a low battery and thus can't make the engine spin... you'll here a fast clicking from the solenoid engaging and disengaging as voltage oscillates. Normally one doesn't hear it because... the motor spins, the engine tries to start and there are plenty of other noises.

In any case, I am familiar with... percussive testing of starters. The problem at present is that this has happened, I think, three times in 15 months. Thus I don't have a repeatable problem to diagnose yet. Thus I was wondering whether it was worth it take everything apart BEFORE I had an issue, to avoid the dreaded call from my SO 'this FINE VEHICLE isn't operating according to spec, please do something about it' (words employed may not match what I wrote exactly, of course).

[georgebest]

before i had an issue, to avoid the dreaded call from my so 'this fine vehicle isn't operating according to spec, please do something about it' (words employed may not match what i wrote exactly, of course).

lol!

[//m320is]

This happens to my E38 all the time. I am able to rule out the ig switch as I have a remote start on the car and when it wont turn over with the key I have tried the RS with no luck. It will sometimes start right up, it will sometimes hang for 2-3 seconds, then turn over and sometimes when its actually engaging it will cut out and come back on real quick (The starter). I initially thought it was an EWS thing, but the more and more I look I feel its a better chance of being the starter relay, which I guess is buried down in the ebox under the DME's? This is on the v12, I don't know if the 8's are the same. Has yours ever cut in and out while attempting to start before? The weirdest thing is almost without fail I can start it up, drive to say the store or something, shut it off, come out 5 minutes later and it will not start, its awesome when going and fueling up, wait 2-3 minutes and then it will start. Once the initial failure happens, at that point I can drive around town all day and it doesn't happen again....its really troubling. Has anything like that ever happened?

[racer2086]

To all these people, I think your starters need a rebuild. It will have intermittent problems as you describe due to wear.

If it is very intermittent, don't worry about it, but you will probably need a new starter or a rebuild soon.

[nmlss2006]

racer, noted, so starter first. On the list. I wonder if it would be best to take it to the local rewinding shop.. it's probably going to be as good as a 'remanufactured' one.

[racer2086]

I have done that with many of my starters and alternators. In fact, my shop looked at my alternator I took out at 170k miles for an unrelated job and said it was in perfect shape and not to do anything to it. I'm at 233k now.

The usual problem is the starter stopping at a dead spot on the brushes/winding. After a try or two it can bump the starter enough to get going again. Again, this is my experience in other more "simple" cars, but matches the symptoms of your problem exactly.

[acspecialists]

Um, correct me if I am wrong its late and I have done no research. The ignition switch does not crank the engine the DME does? I bump my key and the engine cranks and starts on it's own even after I release the key. That being said you can pull the drum switch off of the column and clean the contacts pretty easy.

[nmlss2006]

acs, you are correct, mostly. But if there is no signal from the switch because it's faulty, the DME will never crank. Which is why I suspected the switch.

Now racer is making a lot of sense about the starter - and my experience does match his, I had just read that the switches are also delicate.

I'll keep everyone updated as usual, though this one will be longer term, I think. I still have to get the AC to behave as priority one.. it's STILL odd.