Don't make me call CarTalk.
March 30, 2008 9:51 PM   Subscribe

Help with my friend's car trouble...

So I got a call from a friend with this: 1 month ago her car engine failed to start. She turned the key, the lights went on, the engine sounded like it was going to turn over appropriately then she just kept hearing a recurring screech from the the thing and it wouldn't start. At that point her battery and spark plugs were only 6 months old (this is a 2003 Toyota Solara I think).

She called AAA to get it towed and the guy that came ran diagnostics on site after attaching electrodes to her battery. He said the battery was surprisingly underpowered given its relative youth, gave her a receipt with some metric of the batteries inadequacy and juiced it up with his gadget, apparently buying her a week of time. It started without trouble.

She took it the next day to a mechanic who thought the alternator was busted and he replaced both the alternator and the battery. From there the car started and ran fine until today. Now it's doing the same thing it was a month ago. Engine rumbles but fails to fully start.

Any ideas? Also, is she entitled to ask for repairs of the problem without being charged an arm and a leg? She paid almost $500 for the work done last time.
posted by drpynchon to Travel & Transportation (12 answers total)
I suspect what she has is a slow "leak" of electricity from an accessory or system in the car which should turn off with the key but isn't doing so.

Typically, this could be:

* A new stereo which was wired up incorrectly so that it has juice all the time, or a new stereo with high stand-by power requirements

* A small bulb (like the trunk light or an under-hood light) which isn't going off when the lid is closed like it is supposed to.

If this is really the case, she should notice the problem more the longer she lets the car sit between starts. However, a healthy battery and alternator should be able to recover from these slight injustices as long as the battery isn't completely drained each time.

Alternators are fairly easy to test. You can do so with a cheap volt meter; simply put the positive and negative leads to the corresponding lugs on the battery. Car off, a typical decent battery will read 12 - 12.5 volts. With the car running, you should see that jump to 13.5 volts at idle, perhaps as much as 15 volts at a higher engine speed if the battery is really discharged.

It's possible the second battery is a bum unit. But I'd check for stray voltage leaks as I mentioned above first.
posted by maxwelton at 10:17 PM on March 30, 2008

Electrical gremlins are impossible to sort out except by the most dedicated shade-tree mechanics. You need a pro with a wiring diagram and a multimeter and a few years of experience at this sort of stuff to suss this out.

Basics, tho - have the battery tested, in case as maxwelton suggests it's defective. Have your mechanic also check out the voltage regulator and solenoid, and also the grounding strap. After that, they'll need to check for shorts and voltage drains. Parts for this will probably be cheap, but you're gonna get killed in man-hours diagnosing what's wrong, and you may need to make several trips back to the garage before they finally figure it out.

Also, I'd be wary of a mechanic that replaces rather than rebuilds the alternator. You can make a stronger unit than stock using aftermarket components, and it will cost the same or less and be a good deal more reliable than a new unit. Most of the mechanics I've dealt with use a local alternator shop to do the work for them.
posted by Slap*Happy at 12:33 AM on March 31, 2008

The screetch is probably the fan belt, and symptomatiuc of a dead or sick alternator. Get a replacement.
posted by mattoxic at 4:11 AM on March 31, 2008 [1 favorite]

My first thought, although this should've been obvious to a mechanic if it's really the problem, was that the starter is failing, because "screech" suggests the grinding of the starter's pinion against the flywheel when they don't engage properly. It can't be the alternator belt (I assume this is what mattoxic means by 'fan belt') unless the engine is already turning over, which the early part of the question seems to indicate wasn't happening. Even if it were turning over, I've never heard a belt squeal when an engine wasn't running under its own power; the starter motor alone can't spin the engine fast enough for that.

It would help to have some clarification of whether the engine is turning over, because the question is not clear:

...sounded like it was going to turn over...

...Engine rumbles...

posted by jon1270 at 4:53 AM on March 31, 2008

The starter might be the problem; as starters fail they require more and more power and can mimic a dying battery. I just went through this on my truck.
posted by TedW at 6:09 AM on March 31, 2008 [1 favorite]

grounds could be dirty, loose or rusty.

first thing I check after ham-fisters replace all the possible parts.

have someone check for voltage drop across the pos and neg cables

find a good indie to have a look at it. a small, dirty shop that always has a bunch of cars in front, not the same cars for months, some of then nice and new, is a good bet. if you can find a shop with 'import' or 'foreign' in the name, even better!
posted by KenManiac at 9:31 AM on March 31, 2008

If something is drawing down the battery when the car is parked you will get a small arc when you disconnect and re-connect a battery cable. The fly in the ointment is that with some cars you need to follow an arcane procedure to reset the computer every time you disconnect the battery or you get a bogus check-engine-light.

A screech usually indicates a loose belt. Instead of using a different belt for everything, modern engines use a “serpentine belt” to power the fan, alternator, power steering pump and etc. Re-tensioning a loose serpentine belt takes about five minutes and two tools and a little finesse... and, if the guy actually replaced the alternator, re-tensioning was a part of the job.

When a belt slips it tends to glaze on the side that contacts the pulleys, and that makes it slip even worse. A glazed belt needs to be replaced. You can buy one on-line for about 30 bucks.

Just some thoughts from a former shade tree mechanic.
posted by Huplescat at 12:33 PM on March 31, 2008

I wanted to thank everyone for their answers, all of which have been very helpful. Again, the description was second hand so apologies on the lack of clarity. The best I can get (and again, I'm not even exactly sure what it means for an engine to turnover as I'm a car moron too) is that when she turns her key she gets more than the slight clicking sound of the starter itself, but also the cranking sounds of the engine but it won't complete umm.. start and then the high pitched belt-like noises begin if that helps.
posted by drpynchon at 10:10 PM on March 31, 2008

"Turning over" means the crankshaft of the engine is being rotated by the starter motor.

When you turn the key, you're essentially flipping a little, low-amperage switch in your steering column. The current through that little switch energizes an electromagnet which forces together the contacts of a big, spring-loaded, high-amperage switch called the "starter solenoid," which is somewhere under the hood. The clicking sound you mentioned is the sound of the solenoid contacts coming together. Sometimes a battery is so weak that it can't keep the solenoid solidly engaged (let alone rotate the engine) so the solenoid engages and disengages repeatedly while you're turning the key, making that discouraging rapidfire clack-clack-clack sound.

If all is going well then current flows from the battery, through the solenoid, to the starter motor. The starter motor causes the engine to rotate or "turn over" as it does when the engine is running, only slower (RuvRuvRuvRuv). If the battery is too weak to fully rotate the engine, it might just move a little bit and then stop (Ruv....). Assuming the battery has enough power to keep rotating the engine for a few moments, the spark plugs fire and ignite a mixture of fuel and air that has been drawn into the cylinders; the extra energy from these first explosions rapidly accelerate the engine and it begins running under its own power (Vroom!).

It would help to know how far through this startup process the car is getting.
posted by jon1270 at 2:16 PM on April 1, 2008

jon1270, it sounds like it's getting right to RuvRuv followed by SqueakSqueakSqueak and no Vroom.
posted by drpynchon at 6:19 PM on April 2, 2008

Sorry to say it, but I think your friend is going to have to find a local mechanic. My experience (limited though it is) is that if there's enough power to turn over the engine, then there's also enough power to fire the spark plugs. I just don't see the battery/charging system as being the problem. Furthermore, I don't know what would be squealing after the engine stops turning over unless it's just a bad bearing in the heating/AC blower motor, which would be almost certainly be unrelated to the car's failure to start. Anyhow, the potential for me to mis-imagine the situation, combined with the large number of possible causes for the situation as I do imagine it, make it pretty unlikely we're going to get anywhere. I wish your friend luck; I don't envy her the feeling of being at the mercy of people who don't seem to know what they're doing.
posted by jon1270 at 7:36 PM on April 2, 2008

No worries jon, I appreciate your and everybody elses help with this.
posted by drpynchon at 7:15 AM on April 4, 2008

« Older Singularity + Sci-Fi = My Nerdy Request   |   Give me your best book of taxonomies. Newer »
This thread is closed to new comments.