Weird Alternator Problem - help please

Pete The Biker said:

Well, more investigation today, and Datatek gets the prize for the best reply! - Thank you very much!

It remains to be seen whether this will be a permanent repair, and I do wonder whether the water was the cause or whether this was just a coincidence.

Happy New Year everyone!

Pete

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Hi Pete,
What a wonderful repair!
The day the alternator got wet, did the car sit out out in the extreme cold that night? It is possible the water reached into the stator coils and then FROZE?

When water starts to freeze it EXPANDS by about 9% with an ability to exert extreme pressure on the place where it is at the time.

Could freezing water have forced the stator windings out of place?

It's hard to see what else could have done it.

Next time you need to do this job, for insulation and security of the copper wires, warm the whole thing up in the oven so it's just about too hot to handle, which makes sure it is dry through and through, then mix Araldite and pour it into the windings that need to be secured. The warmth makes the epoxy nice and runny and it fills in between the wires, then sets hard. Buzzing transformers can be "cured" doing that.

CharlesY

CharlesY said:

Hi Pete,
What a wonderful repair!
The day the alternator got wet, did the car sit out out in the extreme cold that night? It is possible the water reached into the stator coils and then FROZE?

When water starts to freeze it EXPANDS by about 9% with an ability to exert extreme pressure on the place where it is at the time.

Could freezing water have forced the stator windings out of place?

It's hard to see what else could have done it.

Next time you need to do this job, for insulation and security of the copper wires, warm the whole thing up in the oven so it's just about too hot to handle, which makes sure it is dry through and through, then mix Araldite and pour it into the windings that need to be secured. The warmth makes the epoxy nice and runny and it fills in between the wires, then sets hard. Buzzing transformers can be "cured" doing that.

CharlesY

Click to expand...

Good advice about drying and epoxy as the insulation failure is usually caused by the windings fretting with vibration. Maybe the windings were moved by ice and then vibration caused the failure?

CharlesY said:

The day the alternator got wet, did the car sit out out in the extreme cold that night? It is possible the water reached into the stator coils and then FROZE?

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The pay and play was on December 12th when it got muddy, and the Rangie saw temps down to -10 from then until last Friday, but it started and ran fine through that period. There was no hint of any problem until I splashed around under the engine bay that day. Between when it actually got wet last Friday and when I fixed it on Sunday temps were above freezing.

What you and Datatek suggest is not impossible i.e the ice had previously caused a weakness. However it does seem that it was the water which actually caused the problem or at least exposed a weakness which may, or may not, have been due to ice.

The epoxy idea is a good one, and I may well go back and do that once I am happy that the repair has stood the test of time. I would be reluctant to do it until then in case I need to dive back in and have another go e.g. at the insulation.

It's certainly an interesting case and google searches haven't revealed anything quite like it elsewhere especially the noise.

Thanks everyone for your interest!

Pete

Pete The Biker said:

The epoxy idea is a good one, and I may well go back and do that once I am happy that the repair has stood the test of time. I would be reluctant to do it until then in case I need to dive back in and have another go e.g. at the insulation.

It's certainly an interesting case and google searches haven't revealed anything quite like it elsewhere especially the noise.

Thanks everyone for your interest!

Pete

Click to expand...

Remember, the alternator generates alternating current, but the frequency varies with engine speed.

If a stator wire come loose, the reversing magnetic forces on even ONE turn of wire could be enough to set up a vibration at generator frequency, causing you to hear a bad noise, and to rub insulation off the wire, leading to a short to earth.

Your cable ties may hold the windings securely, but I would be tempted to use the epoxy, both the secure the wires, and to replace what MUST be defective insulation on the affected bit of wire.

CharlesY