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Author Topic: Alternator troubles!  (Read 7543 times)
Shag55
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Shag Leone, SL-1racing


« on: October 15, 2012, 22:03:53 pm »

I've been having trouble with my alternators going out. It seams that if I just cruise it around they are ok but when I race it or get the RPMs up over 6500 they keep going out. It's the diod inside that's burning out. I've had to rebuild 4 already and just finished off another on saterday at the Dyno. I've posted this around but looking for some further insights.
What you think?
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325hp and 290# torque @17psi on 91 pump
383hp and 324# torque @23psi on 50/50 mix
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Erlend / bug66
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« Reply #1 on: October 15, 2012, 22:28:11 pm »

tight belt?
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Shag55
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Shag Leone, SL-1racing


« Reply #2 on: October 15, 2012, 22:38:15 pm »

No not tight.
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325hp and 290# torque @17psi on 91 pump
383hp and 324# torque @23psi on 50/50 mix
Shag55.sl1racing@gmail.com
Facebook at SL 1 racing
Andy Sykes
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« Reply #3 on: October 15, 2012, 22:55:49 pm »

Hi do you know what voltage you are getting to at 6500 rpm I guess it's an internal regulator  any battery issues and are they all different alternators ?

Cheers andy
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Shag55
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Shag Leone, SL-1racing


« Reply #4 on: October 15, 2012, 23:22:35 pm »

Don't know voltage there. Battery is new 1200 optima dry cell. Last one I bought a new interstate and failed the same. No other electrical problems with the car.
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325hp and 290# torque @17psi on 91 pump
383hp and 324# torque @23psi on 50/50 mix
Shag55.sl1racing@gmail.com
Facebook at SL 1 racing
Peter
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« Reply #5 on: October 16, 2012, 08:37:38 am »

are you maybe drawing too much current due to all efi related parts? Huh
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DWL_Puavo
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« Reply #6 on: October 16, 2012, 12:18:48 pm »

Too much current drain shouldn't be a problem - we raced 6 hours with 600W halogens on the front and didn't have any power left on a battery after one hour - a.k.a. draining all the power an alternator could give for six hours straight. Alternator was an 55A bosch original unit with internal regulator.. There also rpm range was 3000-6500 for the whole time, std sized belt pulleys.

What about too loose bearings and un-balanced fan -> mechanical problem / vibration?
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Shag55
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Shag Leone, SL-1racing


« Reply #7 on: October 16, 2012, 15:50:07 pm »

No mechanical problems. Good bearings, welded and balanced fan.
What wierd is the dummy light is fine then starts getting harder to turn off then a little harder till finally it won't go off.
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325hp and 290# torque @17psi on 91 pump
383hp and 324# torque @23psi on 50/50 mix
Shag55.sl1racing@gmail.com
Facebook at SL 1 racing
Peter
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« Reply #8 on: October 16, 2012, 16:01:26 pm »

If the diodes are burning through, i think it has something to do with the current that goes through them (that is too high)
What else can burn diodes? just thinking here
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Andy Sykes
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« Reply #9 on: October 16, 2012, 16:29:20 pm »

i would check you connection to the battery is ok sounds like the diodes are overheating

cheers andy
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I love the haters they make me famous.

im building this not just putting parts together, they are two totally different things

Your only here once turn it up to 11
Shag55
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Shag Leone, SL-1racing


« Reply #10 on: October 16, 2012, 17:26:50 pm »

Thanks. I did. I replaced the terminals and made a throughbolt for the ground that bolts through the chassi and the tranny ground bolts there from underneath to keep it all tied together. Both my tranny case and engine case are not painted and I have solid mounts. Grind should be good.
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325hp and 290# torque @17psi on 91 pump
383hp and 324# torque @23psi on 50/50 mix
Shag55.sl1racing@gmail.com
Facebook at SL 1 racing
Andy Sykes
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« Reply #11 on: October 16, 2012, 19:18:47 pm »

Just an idea I have seen brushes jump off slip rings at high rpm can you check for any signs of arcing on the slip rings ?

Cheers andy
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I love the haters they make me famous.

im building this not just putting parts together, they are two totally different things

Your only here once turn it up to 11
Andy Sykes
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« Reply #12 on: October 16, 2012, 19:59:31 pm »

Another idea your battery does it have a low internal resistance as after discharge it may pull a lot of amps ?
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I love the haters they make me famous.

im building this not just putting parts together, they are two totally different things

Your only here once turn it up to 11
Shag55
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Shag Leone, SL-1racing


« Reply #13 on: October 16, 2012, 21:08:22 pm »

Idk but I've used 2 diffrent alternators and two diffrent brand new batteries.
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325hp and 290# torque @17psi on 91 pump
383hp and 324# torque @23psi on 50/50 mix
Shag55.sl1racing@gmail.com
Facebook at SL 1 racing
Andy Sykes
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« Reply #14 on: October 16, 2012, 21:15:56 pm »

Ok I'm running out of ideas what about the cable from the alternator to the the battery  is that ok any joints that may arc ?
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I love the haters they make me famous.

im building this not just putting parts together, they are two totally different things

Your only here once turn it up to 11
Fiatdude
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« Reply #15 on: October 16, 2012, 21:23:41 pm »

Shag --- if you want to barrow my battery for the ghia for the weekend your welcome to it --- so you can use it during the cruise or for racing let me know -- it is all charged up a ready to go
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Shag55
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Shag Leone, SL-1racing


« Reply #16 on: October 16, 2012, 21:47:08 pm »

Thanks Harold! But I got a new spare interstate. Just trying to fix the problem.
Are you going bye the way?
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325hp and 290# torque @17psi on 91 pump
383hp and 324# torque @23psi on 50/50 mix
Shag55.sl1racing@gmail.com
Facebook at SL 1 racing
Fiatdude
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« Reply #17 on: October 17, 2012, 02:59:20 am »

Nope -- --- going try to have the car running for drag day
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Fiat -- GONE
Ovalholio -- GONE
Ghia -- -- It's going

Get lost for an evening or two -- http://selvedgeyard.com/

Remember, as you travel the highway of life,
For every mile of road, there is 2 miles of ditch
TexasTom
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12.58@106, 7.89@89 Texas Motorplex 10/18/09


« Reply #18 on: October 17, 2012, 12:58:06 pm »

Do you use the factory wiring harness to the alternator and battery?
I see what I would call premature failures on my customers cars over the past 6-8 years ...
What I like to do is add another, much larger charge wire from the alternator. I typically run an 8 guage wire (typical stereo power cord here) from the alternator to the battery lug on the starter, in addition to the factory wire that runs the other direction to under the rear seat. Voltage goes up to the battery and systems in the car and I've seen much better current flow on original harness cars.
If nothing else, it's an easy implementation and only takes about 33 inches to make the run.

Unfortunately I don't yet have any LONG term results as I've only been doing this for about 5 years, but looks good so far ... much less failures, even on 20+ year old alternators!
TxT
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Shag55
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Shag Leone, SL-1racing


« Reply #19 on: October 17, 2012, 13:26:38 pm »

I thought the same thing Tom but 1.5' of #8 to 1.5' of #4 has less loss then 3' of #8. I may try though.
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325hp and 290# torque @17psi on 91 pump
383hp and 324# torque @23psi on 50/50 mix
Shag55.sl1racing@gmail.com
Facebook at SL 1 racing
javabug
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WHAT'S UP WID DA BOOM BOOM???


« Reply #20 on: October 17, 2012, 14:33:57 pm »

If nothing else, it's an easy implementation and only takes about 33 inches to make the run.

Kymco's monster cable:



http://www.thesamba.com/vw/classifieds/detail.php?id=506399
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Mike H.

Sven was right.
Shag55
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Shag Leone, SL-1racing


« Reply #21 on: October 17, 2012, 15:24:13 pm »

This is a thick jacket 8guage cable that runs from the alt to the starter not battery.
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325hp and 290# torque @17psi on 91 pump
383hp and 324# torque @23psi on 50/50 mix
Shag55.sl1racing@gmail.com
Facebook at SL 1 racing
javabug
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WHAT'S UP WID DA BOOM BOOM???


« Reply #22 on: October 17, 2012, 15:27:28 pm »

Correct; mine goes to the starter.
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Mike H.

Sven was right.
TexasTom
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12.58@106, 7.89@89 Texas Motorplex 10/18/09


« Reply #23 on: October 17, 2012, 18:03:25 pm »

I thought the same thing Tom but 1.5' of #8 to 1.5' of #4 has less loss then 3' of #8. I may try though.

Don't understand the 1.5' thing, but darn near anything is better than 8 feet of 40 year old 10 gauge! LOL
TxT
« Last Edit: October 17, 2012, 18:09:39 pm by TexasTom » Logged

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