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Discussion Starter · #1 ·
Hey all,

I have a 16v that is on its 3rd starter in the last few months while I've been restoring the car. It's never driven on the road.

Here's the story: I put a new starter in and it starts right up. Then a month or so later it will suddenly die on me. No crank. Won't jump. Won't even spin on a bench test.

I'm 95% my wiring is clean, grounds are good, fuses and relays are good.
I'm so close to getting this ready for an Out Of Province inspection but this is going to kill me.
I can't even replace the starter anymore because it will probably just die again.
I'm getting a nice collection of shiny, new, dead starters.

What is my car doing to all these starters?
 

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1988 Scirocco 16v (Wilda); '02 Passat 1.8T wagon (The Brick); '09 Jetta Sportwagon (wifemobile);
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Or a MkIV 2.0 auto trans starter. Bolts right in. Minor wiring change needed ('50' and '15a' get spliced together, and a new plug attached to that.)
Spins the engine up quite nicely - cranking speed is significantly better than the stock starter.

You're "95% certain" that the battery cables are in good condition. Have you done voltage-drop checks on them, while cranking the engine? Also, confirmed that the battery is actually fully charged, and in a good state of health?
 

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Discussion Starter · #6 ·
Hmmm okay I’m starting to question my battery at this point. Its about 6 months old but perhaps I have not been charging it frequently enough. Would cranking on a weak battery damage the starter to the point it won’t crank at all?
I’ve redone the battery cables and grounds to the engine, taken them off, cleaned them, got a new starter and it died within a few weeks.
Would a stronger starter help me? I’m not sure it’s the answer because the car generally doesn’t need to crank that much before starting.
Also this starter everyone suggested does not have the drive end that sits in the bushing, is that not a problem?
 

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Discussion Starter · #7 ·
I’m starting to question my battery at this point. Its about 6 months old but perhaps I have not been charging it frequently enough. Would cranking on a weak battery damage the starter to the point it won’t crank at all?
I’ve redone the battery cables and grounds to the engine, taken them off, cleaned them, got a new starter and it died within a few weeks.
Would a stronger starter help me? I’m not sure it’s the answer because the car doesn’t need to crank that much before starting.
Also the pinion gear on the larger starter that everyone suggested does not have the drive end that sits in the bushing, is that not a problem?
 

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Google voltage drop test to test your wires/cables. All you need is a starter that is strong enough to crank over the engine. Since, most of us believe stronger is better, the SR0407x diesel starter fills that bill. The icing on the cake is that it's lighter, no transmission bushing to be concerned about, and it spins faster. Whoever came up with that idea, I would buy them a beer.
 

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Discussion Starter · #9 ·
Okay so I hate when people don't follow up when they figure it out so here it is.
Theory unconfirmed:

I have been working on the car on jack stands with the battery hooked up. My pinchwelds are bare metal thus grounding the car/battery to the garage pad, draining the battery for days at a time. The low voltage has damaged the starter from repeated cranking and little recharge as I don't run it for very long. This is why my starter wont work now even with a booster pack.

Does my theory have any non-believers?
 

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Well it takes a man to say it was my fault. Along with, you're right honey, I was wroon, not right(the Fonz). Drop it to the floor, charge the battery and prove yourself right!
 

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I have been working on the car on jack stands with the battery hooked up. My pinchwelds are bare metal thus grounding the car/battery to the garage pad, draining the battery for days at a time.
I'm not a believer and was never a believer that leaving a battery on a cement floor causes it to drain out. I was taught that while in college and I questions the instructor and I was never given an answer that was satisfactory. I believe the answer was "Because I said so" but that may have been my Dad answering my questions when I was young.

Batteries need to be good before you do any testing. Just because you have a new battery does not mean it's good. Testing is the key to determine if the battery is good or not. If the battery goes dead, you have lost a lot of life of that battery. Draw a battery down to nothing a few times and that battery is NFG. Even if it is new, it's NFG. Never bring a lead acid/AGM battery past 50% or some damage will occur. If you can stay that happened to your battery, it's probably NFG. Only testing will confirm that theory. The easiest way is to send it in to a battery store. You will eventually walk out with a good charged battery or a new charged battery.

A starter is one of the most basic electrical parts of a car. You need a large power and ground cable/wire. These cables need to be connected properly. A voltage drop test will confirm it that the cables work. Again, testing confirms, looks is not a test. "Looks Good" is not a test result. Do not know how to perform a starter voltage drop test? Google it. If the circuit cannot be activated, then an ohm meter can be used, but that is not as accurate for heavy loads that a starter circuit has.

Once you have a good power and ground connection, if you put power to the circuit 50 tab, it will crank. If it does not, the engine is seized or the starter is faulty.

It's good to have theories, but testing will confirm if those theories are valid. Looking for validation here is not really a good place to start. I prefer Fluke, but any good DVOM is a better place to get your validation.

Cement, bare metal, and jack stands will not cause a battery draw. Unless the water level is above the top of the battery. If that is the case, I hope you have good flood insurance.
 

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I have been working on the car on jack stands with the battery hooked up. My pinchwelds are bare metal thus grounding the car/battery to the garage pad, draining the battery for days at a time.

Does my theory have any non-believers?
Yeah, nah. Just for the record, this makes no sense at all.
 

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I’m starting to question my battery at this point. Its about 6 months old but perhaps I have not been charging it frequently enough. Would cranking on a weak battery damage the starter to the point it won’t crank at all?
Absolutely. It's Electrical 101.
How to explain this.... Starter motor (just like any motor) is rated in "watts used at xxx volts input." If it's say, 1200 watts, at 12v, that makes for 100 amps draw. Follow?
Now, drop the input voltage to, say, 10v. Now your current draw just went up to 120 amps. And, because "amps = heat", as the amperage goes up, so does the internal temperature of the load (your starter.) And, starter motors don't have a cooling fan in them.
Get the supply voltage too far under spec, and you will, eventually, melt the insides of the starter.
I’ve redone the battery cables and grounds to the engine, taken them off, cleaned them, got a new starter and it died within a few weeks.
As Butcher previously posted, "looks" or "seems" is not a valid test data. Exception would be things like "damn, that ground strap is seriously corroded, green, and crunchy. I should replace that."
Would a stronger starter help me? I’m not sure it’s the answer because the car doesn’t need to crank that much before starting.
Also the pinion gear on the larger starter that everyone suggested does not have the drive end that sits in the bushing, is that not a problem?
No, because the newer starter doesn't need it. The trans bushing is to support the pinion gear (read: keep it from walking off of the flywheel.) Newer starter (say, the MkIV 2.0 starter) has that support internal to the starter case.

Thanks everyone.
At the moment it appears I was correct. Low voltage from crank and not enough recharging. Battery charger and new starter have resolved the issue.
(y)(y)
 

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Discussion Starter · #18 ·
Absolutely. It's Electrical 101.
How to explain this.... Starter motor (just like any motor) is rated in "watts used at xxx volts input." If it's say, 1200 watts, at 12v, that makes for 100 amps draw. Follow?
Now, drop the input voltage to, say, 10v. Now your current draw just went up to 120 amps. And, because "amps = heat", as the amperage goes up, so does the internal temperature of the load (your starter.) And, starter motors don't have a cooling fan in them.
Get the supply voltage too far under spec, and you will, eventually, melt the insides of the starter.
As Butcher previously posted, "looks" or "seems" is not a valid test data. Exception would be things like "damn, that ground strap is seriously corroded, green, and crunchy. I should replace that."
No, because the newer starter doesn't need it. The trans bushing is to support the pinion gear (read: keep it from walking off of the flywheel.) Newer starter (say, the MkIV 2.0 starter) has that support internal to the starter case.

(y)(y)
Ohhh okay! So it sounds like my jack stand theory is wrong. What seems like I got right is that I just got lazy and wasn’t recharging the battery enough between cranks. Thanks for that explanation. Actually very helpful.
And RE: testing. By “looks” I mean I did in fact test the battery and the test result “looked” good. It’s semantics because I’m just trying to include that I may still be missing something beyond testing ground straps and battery voltage. That’s all.
And that’s great to know about the MK4 starters for when I realize I’m still wrong and have to replace the starter again!
Thanks again!
 

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Being an ex-Shop Foreman, anytime a technician came to me and said it tested good, looks good, etc. was code for, no tests were done. It took awhile, but once I let them know my expectations, I soon got, the alternator is charging a 13.6v, the voltage drop on the cables is .1v, etc. After awhile, the techs did not come to me for help on the easy stuff. They figured it out themself.

I get that most people do not know what or how to test, but once you do, there are so many things that you will figure out without any help. Many of the test that are good to know are so simple. The only stumbling block is to learn how to do them. It takes seconds and costs nothing to do a starter voltage drop test. Certainly faster than replacing all the power and ground cables and having the same problem.

Your theory seems to be based that leaving a battery on cement causes the battery to short out. Because I've always questions that theory, I seemed to get what you were saying. To this date, no one can explain why cement [that does not conduct electricity well] would short out a battery faster than a metal battery tray.
 

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Your theory seems to be based that leaving a battery on cement causes the battery to short out. Because I've always questions that theory, I seemed to get what you were saying. To this date, no one can explain why cement [that does not conduct electricity well] would short out a battery faster than a metal battery tray.

 
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