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Discussion Starter · #1 ·
2001 NB 1.8T AWV. daughter had several lights come on last week on the way to work, no power, then would not start, there was a blown fuse. replaced and now it runs good, however, the batter voltage is only 11.97, even after charging. Advance Auto battery tester says good battery but only charging at 12.8 volts at idle with no lights, fan etc. on. I took it home, charged the battery then let it sit overnight. battery voltage down to 11.0v but it started. now it shows 13.3 volts on the battery while running until it warms up then down to 13V. Turned on fan, lights and radion voltage goes down to 12.87. ran for 10 minutes, then shut of engine, battery voltage dropping from 12.1 down to 11.97 in just a few minutes. it does have a monsoon radio (OEM) and amp but this is a new problem after having the car for 3 months. Checked amp draw and it was about 17mA before starting the testing this morning if i tested it right.

so, my theory is it could be a bad diode in the alternator since it never charges at 14V like it should. changing the alternator seems like a big job because it looks like you either have to take the fuel rail off or disassemble the front end to put the radiator in "service" position.

Am i on the right track? any suggestions?
 

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A few things.

First if the battery Voltage is less than 12.0 Volts, this means the battery is pretty much fully discharged. It still have power, but is effectively fully discharged.

Do not forget about the ground wires under the battery tray as well, you can search for this info here as well.

Inspect the pulley on the alternator, if it has a plastic cap installed on the front of the pulley, it is a one way clutch pulley. These are known to freeze/seize and/or slip. In your case the pulley would not be frozen/seized.

I think you can remove the passenger side headlight and bucket and remove the alternator through the headlight hole?

Before I would condemn the battery, I would make sure your meter is reading correctly and see if the alternator has a one way pulley that may be slipping. The pulley can be changed with the alternator still mounted if you are LUCKY, of now, you can remove the alternator and spin it in the engine compartment and change the pulley.

Read these threads - http://newbeetle.org/forums/1-8-lit...-failure-what-best-brand-replacement-buy.html

http://newbeetle.org/forums/questio...ring-harness-voltage-regulator-questions.html
 

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I would take the car and have it tested at a auto parts store with their charging system diagnostics computer (this will confirm the problem)

As far as removing the alternator; it isn't that hard. I removed the passenger side headlight and the throttle body and got it out that way. Not really that big of a deal. The reason; I chose going through the headlight, is that I didn't want to disturb the injector seals and have to replace them. They always say to replace them (if you remove the fuel rail) and I have seen people try to skip putting new ones in on other cars, they always seem to end up leaking. I figured I would save money and the hassle, of having to fully remove the rail, all the injectors and replace all the o-rings, etc.

In this video; he undoes the fuel rail, I prefer to remove headlight and remove it out that way.

https://www.youtube.com/watch?v=edmAnTMnOXg
 

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Discussion Starter · #4 · (Edited)
thanks guys. I had the battery tested out of the car at Advance auto and it was good. they tested the charging system and said it was working but weak at only 12.8v instead of closer to 14V at idle with no accessories on. my meter said 13.3v on the battery this morning when it was running with no accessories on.

however, I think I found one of the issues. using the 2 doc attached, I measured the voltage drop across the fuses to find that the radio System fuse (42) had a .2 mV drop. using the chart in the tech bulletin that's a 94 mA (almost an amp) parasitic draw. so it looks like we have the "monsoon amp does not shut off" symptom.

the other draw was fuse 38 - luggage compartment light but it was not on with the hatch closed. it was .1 mV which was 23 mA.

so the total draw was about 1.2 amps when the vehicle was shut off. I i can get the amp to turn off, i will be below the 40 mA limit mentioned in the tech bulletin.

any ideas on the monsoon amp issue? I looked for the relay solution i saw a while back on the forums but couldn't find it.

didn't know about removing the headlight to get the alternator out. I had to do that to replace the washer fluid reservoir a couple of months ago. that's not too bad to do.
 

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Discussion Starter · #5 ·
one more question after reading the other posts about replacing the alternator. if i take the throttle off the intake to get more room, is it necessary to re-adapt the throttle to get things to work right? i don't have a VCDS (yet) but if that is the case I will have to get someone to do it for me ($100/hr minimum 1 hour, best price for VW shops around here)
 

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I believe on ALL German cars that anything that has the word "Adapt" associated with it will in fact "Adapt" on its own, maybe a bit slower than if you force it via software, but most modern vehicles need to be able to "Adapt" on their own without specialty software.

I did not remove my throttle body on my car when I rotated the alternator to replace the one way pulley.
 

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Discussion Starter · #7 ·
I was going to replace the alternator so I would have to remove the throttle assembly to get it out from what i can tell. I saw where you just replaced the clutch and were able to work on it by rotating it so the pulley was up. I agree, it should not need to be "adapted" but so far it would not surprise me if needed a re-calibration.

Put the radio system fuse back in, turned the OEM radio on (replaced the aftermarket that I think was causing this issue among others), then shut everything off. will check in a bit if the battery voltage is dropping again. so far it looks good. If so, i will check the chargin system again before replacing the Alternator.
 

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Almost ALL software or tools that allow "clearing" of Adaptations is for service shops so they can "reset" the Adaptations to see if the repair made a difference without having to drive the car for days or a week.

If the car has "Adapted" to say a vacuum leak over time and the vacuum leak is repair, the engine idle may be lower than normal, as an additional air source has been removed. The idle will "Adapt" over time, however, if the shop "Clears/Resets" the Adaptations, then the idle should immediately settle to the proper RPM without needing to wait or drive the car.
 

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Discussion Starter · #9 ·
ok then it wont hurt much if anything if it is removed and reinstalled. sorry for the basic questions.

Just drove it after it sat for a few hours with the radio fuse back in. battery voltage stabilized at 12.3v like it should and didn't drop further. Drove it to pick up my daughter at work and when we got back i checked the voltage at the battery while idling - 13.3V. still seems low but with all accessories on it only drops to 12.7-12.8V.

is this normal for the beetle?
 

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If you remove the throttle body and reinstall without changing anything, IMHO, then there should be no change in idle or a requirement for "Adapation" of anything.

Typical charging Voltage for most cars tends to be between 13.5-14.5 Volts.

A fully charged battery should read 12.6 Volts. But a fully charged battery 12.6 Volts is no guarantee that the battery is in fact good.

You may want to try an measure the charging Voltage at the back terminal of the alternator to make sure there is no Voltage drop between the alternator output terminal and the battery/fuse box.

Keep in mind there can be problems with the fuse box and ground under the battery. Also one way clutch can slip.

I would probably suggest replacing the one way clutch to begin with anyway, I would NEVER use the one way clutch that cam on a reman alternator anyway.

Key note on the one way pulley, I tired to replace it with the alternator in place but was afraid I was going to break the tool. So I removed the alternator, flipped it upright and then used an impact on the pulley to break it loose, it needed the impact and broke loose very easily with the impact.

Not sure if these alternators can easily have the brush/regulator replaced without tearing the unit open. I know a number of the Bosch alternators on BMW's can easily have the brush/regulator replaced.
 

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Looks pretty straightforward; if you need a oap, a regulator and the bearings are worn, I would look to a high quality rebuild (see if replacing parts is cost effective vs. a replacement alternator). Here is a video; showing the regulator getting replaced; looks pretty straightforward.

https://www.youtube.com/watch?v=vjhqFPG4A6Y
 

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Discussion Starter · #12 ·
Great info. i will look at the tensioner to see if it is bouncing around. If the pulley is locked (probably is, this beetle has had a rough life and is finally getting some love), after watching the video I might give it a try, replacing the regulator and pulley.

Done for today. will update tomorrow. thanks again for the info.
 

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Discussion Starter · #13 ·
This mornings update: battery voltage dropped overnight. all cables are secure on the alternator and battery. the tension pulley does have some movement, about 1/16th of an inch by looking at the tension guide on the top of the tension pulley. it stays in the middle of the range.

I am going to get the voltage regulator/brush assembly and change it out on this alternator to start. next weekends job for now.
 

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I removed the alternator on my 1.8t without having to take off the throttle body, you have to wiggle it around more but it can be done. I think I even removed the headlight bucket to make sure I had the room to get it out. And you have to take off the hose from the intercooler to the throttle body as well.
 

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yep

I removed the alternator on my 1.8t without having to take off the throttle body, you have to wiggle it around more but it can be done. I think I even removed the headlight bucket to make sure I had the room to get it out. And you have to take off the hose from the intercooler to the throttle body as well.
yep we know, :D you could have asked us about what to remove to get the alternator out to save you a little bit of time. You got it out anyhow, good luck.
 
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