Thread: Alternator overheating

Agreed, not any aftermarket unit, the part numbers have to match. Sorry should have qualified that better. Referring to say the Rimmer Bros website, they usually offer 3 options; GENUINE, OEM and AFTERMARKET, however each option has the same part number albeit with different suffixes to differentiate.

I would still strongly recommend Genuine or OEM at minimum.

Originally Posted by Tombie

I would still strongly recommend Genuine or OEM at minimum.

Well I still have no idea if it is a good aftermarket alternator or not, guess time will tell, its installed now.
Have picked it up this morning and everything is fine now, happy days.
Not really sure what the full story is but was told that the old alternator somehow had stuffed the new battery. Had only driven it for 50 minutes with the old alternator installed prior to the installation of the new one.
When they had installed another new battery and then reinstalled the new alternator it is all functioning properly. So go figure.
It would appear as others have suggested that the new alternator was trying to charge a faulty battery and therefore working so hard it was getting excessively hot.
It does make me wonder though when you are out camping or something similar and end up with a completely flat battery by accident, jump start the car and start driving, will I stuff another battery or alternator??
Surely there should be some kind of regulation. Not sure what the problem was to begin with now.
I know a dual battery system would be the answer when funds permit to prevent this, but in the meantime?
Thanks for all the input,was very helpful.

Originally Posted by Tombie

I would still strongly recommend Genuine or OEM at minimum.

Normally I would completely agree. I understand the genuine LR alternator is a Denso so can be purchased as genuine or aftermarket.

In January last year my alternator failed on a Friday afternoon and I needed my car that weekend. I rang the local branch of a well know auto electrics supplier and asked if they had a D3 Denso alternator and they said they had three on the shelf so I went over to get one. When they pulled it out I noticed that it was OEX brand not Denso. I challenged them on that and indicated they said they had Denso in stock - their response yeah - "Denso Type" - I said hang on one is the real thing and the other a knockoff and the guy did not seem to understand the difference.

So my issue was that I wanted a Denso, they had an OEX which I know is a good brand (made ROC not PRC) but is still a knockoff and I needed one now. So the OEX came home with me and it comes with the correct pulley unlike some aftermarket Denso alternators.

Took about an hour to put in and has been fine since - 20 months and about 50,000km.

So happy with it but would have preferred a Denso.

Pricing was interesting - Australian Denso prices ranged from $550 to $1200 for the same item and as it turns out the OEX prices also ranged from $550 to around $1200 so the knockoff costs the same as the original but both have a huge price range so you need to shop around. Mine was $550.

Garry

Originally Posted by jimd377

Not sure what the problem was to begin with now.

Some brands of alternators (including Denso) die by one of the main rectifier diodes "wearing out". The diodes reverse conduct as a safety measure when the voltage is too high (usually around 30V) if the battery is disconnected or the regulator goes haywire or something else causes a high voltage spike. Over time the threshold voltage slowly gets lower due to the decay of the material in the diodes to the point of about battery voltage at which time the alternator discharges the battery very quickly, usually destroying it. If a new battery is fitted then the failed alternator will flatten the new battery very quickly too!

Originally Posted by 101RRS

Normally I would completely agree. I understand the genuine LR alternator is a Denso so can be purchased as genuine or aftermarket.

In January last year my alternator failed on a Friday afternoon and I needed my car that weekend. I rang the local branch of a well know auto electrics supplier and asked if they had a D3 Denso alternator and they said they had three on the shelf so I went over to get one. When they pulled it out I noticed that it was OEX brand not Denso. I challenged them on that and indicated they said they had Denso in stock - their response yeah - "Denso Type" - I said hang on one is the real thing and the other a knockoff and the guy did not seem to understand the difference.

So my issue was that I wanted a Denso, they had an OEX which I know is a good brand (made ROC not PRC) but is still a knockoff and I needed one now. So the OEX came home with me and it comes with the correct pulley unlike some aftermarket Denso alternators.

Took about an hour to put in and has been fine since - 20 months and about 50,000km.

So happy with it but would have preferred a Denso.

Pricing was interesting - Australian Denso prices ranged from $550 to $1200 for the same item and as it turns out the OEX prices also ranged from $550 to around $1200 so the knockoff costs the same as the original but both have a huge price range so you need to shop around. Mine was $550.

Garry

I need to check but i think i paid about 670 for a genuine Denso alternator for
My D4 with warranty from rovacraft in Perth. I was happy to pay that as the original (also denso) had done ~189000km . It was definitely not an "OEX" unit

Originally Posted by Eric SDV6SE

I need to check but i think i paid about 670 for a genuine Denso alternator for
My D4 with warranty from rovacraft in Perth. I was happy to pay that as the original (also denso) had done ~189000km . It was definitely not an "OEX" unit

Yep, couple of weeks ago, mine with pulley ex Rovacraft (I think, as DazzaTd5 sourced it for me) was $660 with pulley

I have just changed mine after 205000km and fitted a new Denso which is exactly the same brand which came off. The car has done very little city driving which is why I have had no problems with it
i did not wish to be stranded with electrical failure anywhere and the cost was same as being quoted $650