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intermittent starter short??

Car: 1986 mazda 626, 2.0L (no brand bashing or anything, it's a waste of time)

Initially one night I go out to the car, everything has been fine, go to start it, there is a massive current drain, then nothing. try again, get some clicks that's it. battery is discharged, remove it. Check for massive shorts, get ~3-400kohms between ground and + battery cables, which is about what I expected with the clock, radio memory,etc. Everything seems ok wiring wise.

Took the battery to the autoparts store figured it blew a cell. Tests good. Charge it back up, start car, it's running ok, start testing alternator, seems not to be putting out enough current. Goto autoparts store with alternator, they are missing the part for their tester to test it. Order a new one. Tonight I realize I f'd up the tests I did and hadn't zeroed the ammeter. So this time they have the adapter, so the alternator tests good there. I put it back on the car and test it again, seems fine. putting out damn near 100amps with *EVERYTHING* on and the engine at about 2500rpm.

So.... I shut off the engine and restart it a couple times, seems fine. I get my voltmeter to do some more alternator tests. I go to start the car and once again huge current draw, battery goes to near zilch. I disconnect the battery and check continuity between the alt B post and the + btty cable, it's there. Cool. I check bettween + and - btty cables, continuity... WTF? So ok I think maybe the alternator had a death throw and is now shorted. I disconnect the cable from the b post and check continuity between the b post and ground. Nadda. Ok. Check cable to the b-post and the + btty, still got continuity. I turn the engine by hand a bit, sill continuity.reconnect b-post, alternator. Alrighty, leap of faith I reconnect connect the battery and check voltage. No big sparks or anything, voltage is the same posts connected to the cables or not. The battery seems to have recovered some charge so I try to start the car. Starter turns a wee bit and then that's it. disconnect battery, repeat continutity tests of battery cable and b-post.

3-400Kohms again.

The only thing that has really changed bettween the there being continuity between the ground and + btty cable has been the starter posisition.

So the question is, is it possible for a starter to be shorted at one location in it's rotation that can draw down a battery? maybe an issue with the solinoid/relay? It seems like this shouldn't be the case, but the check between the battery cables seems to indicate a short somewhere. The starter didn't feel unusually hot, for how long I had idled the engine.

I am wondering if I shouldn't just idle it for awhile with everything on once I get the battery charged up and see if it dies. I am tempted to pull the starter to play with it, can't really reach the end where the wires connect, but I can get at the mounting bolts fairly easy to yank it out.

Anyone got any clues? Obviously there is a short somewhere that's the cause of the problem....

Reply to
Brent P
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Additional Info... the battery has charged up fast both times. the first time I figured the autoparts store tester gave it a boost. But this time, starting out drawing only 2 amps from the charger showing only 12.4 volts, it's back up to 14.8 volts and trickling in charge at only 1 amp. All with one hour sitting on the charger.

Reply to
Brent P

Curious. What is the symptom of "huge current drain"? Did you measure this somehow or see it on the ammeter?

Several years ago, I had a 73 Marquis. When I went to start it one day, I watched the dome light go from bright to very dim in just a few seconds. Smelled something had burned. While troubleshooting, found battery was bad, alternator diaodes had blown and voltage regulator tested bad (external on this vintage). I never thought to look at the starter. Have no idea what went first, but it blew out the charging system. Replaced battery, alternator and voltage reg and ran fine for several years (starter apparently was not part of my problem)

Reply to
bobby

Good old observation.... it's not a normal start... all the power is sucked from the battery.

Unless they died when it happened a second time, alt and battery are good.

Reply to
Brent P

This is absolutely possible. As a matter of fact there was a really nice '56 Golden Hawk at the Studebaker International meet last year that had an expensive, tar-top repro battery explode because of just this occurrance. The guy bought a new battery and drove the car around the rest of the week then went home and a post-mortem revealed exactly what you suspect. when the starter stopped with the brushes in a certain position on the commutator, the windings provided a dead short so when the starter was re-engaged, instead of turning over the engine the battery exploded. Fortunately, this only happened once before he took the starter to a good auto electrical shop and discovered the problem. In your case I would suggest simply a new starter as it's probably easier to find than for a 48 year old car with a 2-year-only production run engine :)

nate

Reply to
Nate Nagel

Thanks, now that I know it's possible, I'll yank the starter and see what's going on. Hopefully I didn't fry the battery or the alternator investigating this. They survived the first shock and that was worse than the second time around.... Come to think of it, this is following the same death throws of the starter on '89 MX6 years ago. (that one exploded the battery)

The battery seems to have taken a charge ok, but the voltage has dropped from about 13.8 to 12.8 from when I took it off the charger at 1am and when I left for work... hope it's still ok...

Reply to
Brent P

12.8 sounds OK to me for a no-load battery that's been sitting off the charger for a while... have to load test it to be sure but my armchair mechanic sez fuhgeddaboutit. If you got a real auto electric shop nearby, or the time to disassemble and test the thing yourself, I'd look at the starter.

BTW I forgot to mention that the 56J I mentioned above was parked outside a 7-11 at the time that the "incident" occurred and the owner had the presence of mind to run in and grab a box of baking soda and a gallon of distilled water immediately, so no lasting damage was done. (I hate to see nice cars get f**ked up!) Damn pretty car too, a silvery/bluish grey with red leather interior. I kinda lusted after it.

The other reason I think that this is your starter is it is about the only component that is directly connected to the +ive battery cable and therefore has the capability of drawing significantly more than 50-60 amps or so without wire frying, and therefore is about the *only* component (other than the remote solenoid, if you have a Bendix-type starter) that could suck the battery voltage to near zero instantaneously, unless the wiring setup of your car is truly wierd.

nate

Reply to
Nate Nagel

the battery was not much discharged. I calculated it takes 8 hours at 5 amps to fully charge a dead battery on my car. I had it on an old non-automatic-shutoff charger 5 hrs one day and 3 the next. Never even got warm.

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