More alternator problems - suggestions for mechanic?

[jaycey001]

Hi everyone

Just a quick update on things so far.
1. my original alternator died due to a failing regulator
2. fitted brand new one and 400 miles later the regulator died, sent it back for replacement
3. fitted 2nd hand alternator, worked for 400 miles and then died
4. had to get a new alternator fitted in Devon due to the 3rd alternator failing, drove home to Suffolk and a day later it has died.

I have found that the last alternator (new one) was really hot and overheating, I suspect that was the reason all the other failed, what suggestions do you have as to why the alternators would be overheating?
The Bongo is off to my mechanic (mazda trained) next week for him to investigate, but if anyone has any suggestions on where to start looking it might be helpful.

All the alternators worked for 400 miles, putting out about 14.2 volts, then they all stop charging, presumably due to overheating.

Thanks in advance.
James

[g8dhe]

The only real reason for it to fail electrically from heat problems is if it was providing more current than expected, they are normally rated to 90 Amps. However there have been in the long past reports that some were being fitted with 70 Amp diode blocks, these tended to fail within the year.
Another reason for over heating is if they get covered in oil the V6 cam seals being the source, the oil runs back down the engine via the alternator and congeals around it blocking cooling.
How was over heating diagnosed ? Was it actually measured or is it an assumption ?

[Northern Bongolow]

If its a diesel check the number one manifold stud ain't broke, the one nearest the alternator rear. the manifold can warp and let out gasses which can take out your alternator diode pack , they are very near.

[g8dhe]

Good point Ady!

[Bob]

I'm still impressed by the technical knowledge some of our peeps have, and happily share.

[nth]

I would hope that by the time the 3rd alternator was fitted that someone would have noticed the oil/soot contamination if that was the case?

[teenmal]

I would hope that by the time the 3rd alternator was fitted that someone would have noticed the oil/soot contamination if that was the case?