I finally have a car problem interesting enough for "Car Talk",...

…but, of course, there is no “Car Talk” anymore. Maybe Troll and Ban, the Doper brothers, can help me figure it out.

Here’s the sequence of events so far. Some of these may turn out to be irrelevant, but I’m trying to be thorough.

  1. The car is a 1999 BMW 3-series with about 138,000 miles. It has a manual transmission.

  2. A few weeks ago, I was driving on a highway and the car started to develop a bad vibration. I got off the highway and nursed the car home.

  3. I took it to a mechanic a couple days later. They replaced the front brake pads and one caliper. When I picked the car up, the vibration was gone.

  4. That night, I drove to my curling club, and on the drive home stopped at a fast food restaurant. When I got back to the car, it wouldn’t start. I’d put the key in the ignition, turn it to start, and nothing would happen. The starter wouldn’t turn at all. I tried it four or five times, and finally it worked. I drove home.

  5. The problem recurred a few days later. I thought it was a battery problem; the starter would work, then not work for a while, then work again. I took the car bettery out, took it to an auto parts store and had it tested. It was marginal, so I bought a new one and installed it. No change.

  6. I did a little more online research and figured it might be a problem with the ID chip in the key. I replaced the battery in the key and the starter worked, but I shut it off before the car actually started. Tried it a few times, and it did the same.

  7. Now I figured I had a different problem, that in replacing both those batteries I’d confused the car’s computer or engaged an anti-theft mode. I called a tow truck to take it to the dealer. The tow truck driver got in the car, turned the key, and it started (with quite a lot of smoke). I think it was just flooded.

  8. I figured the new battery in the key had fixed the problem, so drove it as normal for the next week or so.

  9. Now it has started what it was doing before. I turn the key to start and nothing happens. Well, not quite nothing, the heater fan turns off when the key is in the start position.

  10. Yesterday, it worked. Today, it doesn’t. Thinking back, it seems to be temperature dependent; when it’s especially cold, nothing, when it’s a little warmer, the starter turns like it was new.

Here’s my best guess.The cold is either breaking a circuit (like the clutch interlock switch), or some moisture might have gotten into the starter somehow. The critical temperature seems to be around the freezing point. Can water freeze inside the starter and keep it from turning? I think the vibration and batteries are red herrings. Whatever is allowing moisture in could have been there since the spring; it just never caused a problem before because it hasn’t been cold enough.So, two questions for the assembled wisdom of the Dope; what could be causing this, and can I (or more likely, a mechanic) diagnose and fix it if the problem can’t be reliably reproduced?

Bad connection to the starter motor. The vibration made it worse.

Or a bad starter that is now hitting the dead spot more often than not.

Key, doubtful,but maybe.

Starter solenoid, if you hear a click when you turn the key, then the solenoid is good, which leaves…the starter.

Here is the diagnostic flow chart, of sorts.

How can I go about testing either of those things?

Neither of them seems to explain why the problem happens when it’s cold. It’s supposed to be in the 20s tomorrow, and then back to around 40 starting on Wednesday. I plan to try the car both days and see if it starts.

Grab cables from the battery down near the starter and where it is grounded and wiggle.

Also, cold may be keeping the starter solenoid from engaging. Grease oil road dirt may get in there. Gets thick in the cold. Not fun, but a quick fix is to tap it with a hammer. That’s a one in ten shot I would say.

I’m not super up on (relatively) newer BMWs, but generally chip keys won’t stop the car from turning the starter, they just stop the car from actually starting or sometimes let the car run for a few seconds, flash some cryptic security symbol, and then die. Although the seeming “crank but no start” condition at event #7 would be consistent with it, so that kind of muddles things.

Intermittent silence when you turn the key but normal staring otherwise is a pretty classic symptom of a bad ignition switch or interlock switch. Usually with a bad cable, if it’s still connected enough to intermittently start it’s connected enough to consistently fire the solenoid. So you get a “clunk” instead of silence. It could also be the solenoid, but those also usually (but definitely not always) make some noise if they’re failing only intermittently.

Clutch switch problems during the winter are not at all uncommon because the switch is usually right down by the pedal and it tends to get pretty wet down there as you track snow into the car. If it were my car, that’s probably where I’d start. I’m sure if you do some googling, you can find instructions on some forum or other for how to bypass the clutch switch on your car. I wouldn’t necessarily recommend bypassing it, but you should be able to figure out where the switch is and whether it’s normally open or normally closed so you can test it.

My vote is the starter itself. They do wear out. Both age and the vibration may have moved things just a tiny bit loose so the connection isn’t always being made. Time to start looking for another starter.

Didn’t see your post earlier, but thanks. That diagnostic chart could prove useful.

An online search says that the best way to change the starter is to remove the intake manifold, and I don’t have the tools for that. I’m not sure I can even reach the cables and jiggle them without some minor mechanical surgery.

I’m pretty sure the “chip” used by BMW in 1999 was a RFID chip, that is a passive chip. It would work with a dead battery in the key fob. It is that way in my 98.

I’d guess the ignition switch, if the cables check out. The ignition switch is 17 years old. Find a BMW message board that specializes you your year model (bimmerforums.com to give you a start) and I’d be sure they could help.

I was wondering about that. There’s a rather weak LED light build in to the key (the alarm remote is on a separate fob), so at least that works better now.

The key chip could still go bad, though, couldn’t it, if some connection inside came loose? And can the key be tested without having the rest of the car with it?[sup]*[/sup] It would be a lot easier to hop on the bus and take my key to the dealer than to have the whole car towed in.

The cold weather thing makes me tend to think the key isn’t the problem. The key is inside my apartment, and it wouldn’t cool down that much in the 30 seconds it takes to get the car and start it.

  • I sent am e-mail to my local dealership (where I bought the car, even) asking that question, but haven’t gotten a reply.

My current plan, I suppose, is to try the car tomorrow and listen for the solenoid click. I may need to recruit a friend to listen for me while I turn the key.

After that, I’ll either call my mechanic and make arrangements to drive it (hopefully) in, or there’s a local mobile mechanic service that has decent reviews online, so I may make an appointment with them.

Yes, yes, this is all very interesting but do you happen to know the solution to last week’s Puzzler?

[sub]And don’t drive like my brother![/sub]

Update: I went out today to try the car again and listen for the solenoid. I got in, put the key in the ignition, leaned forward to listen carefully, turned the key…

VROOOOM, started right up. And it’s 24 degrees.

No, but our staff Marine Biologist is Luke N. Atwater.

I just wish I had curling somewhere near me here in North Louisiana.

I would not dismiss the vehicle anti-theft system as the source of the problem yet. Many will allow other things to run, like the lights and fan, but not start the car if the key goes bad. The systems are made to discourage someone from stealing your car, but not to leave you stranded. Crooks don’t want to wait around so some VATS (BMW calls it by another acronym) systems will not start the engine if the key goes bad but WILL start if you wait 10 minutes or so. Even with a bad key.

When you could not start the car and called a tow truck and then he could start the car that is what it sounds like to me. The specifics with BMW are probably more complicated and you really need to have a BMW place look at it. BMWs are not exactly user-friendly to work on yourself.

Don’t be throwing your own parts, money and time at what could be just bad communication between the key and computers.

I had a similar-sounding problem that turned out to be a cold solder joint.

Well, that would kinda suck. I can understand making the car hard to steal, but does it have to be so inscrutable about it?

Plus, I’ve had some repairs done at the dealership in the past; it’s expensive, and I haven’t been particularly satisfied with their work.