The problem dates back to March, when I took my truck in for an oil change. After he change the oil, the tech decided to 'clean' my engine bay and air filter with compressed air. I never clean my air filter, I always replace them at 3,000 miles with the extremely dusty environment I drive in.

Afterwards, when I was driving home and had to merge with traffic on the freeway, I did a WOT run and there was a big bang at the 5,000 rpm mark - almost as though the muffler exploded. The revs then suddenly dropped to 1,500 rpm and down to 0. There were no warning lights or anything of the sort. Following this, the engine refused to start. It would crank, but would not start. Turns out the compressed air caused the high tension cable to loosen, and eventually come off the ignition coil.

The alternator went out that day, so I had it rebuilt with OEM parts. At the same time, the engine kept bogging down every now and then, which was an intermittent problem. Turns out the MAF sensor was kaput, I replaced that as well.

Fast forwarding to May, I was driving around at night with the AC on and my lights had gotten pretty dim. Took it to an auto electrician, who told me my alternator was out. This time, I bought a brand new OEM Mitsubishi Electric unit (OE 90 amp model) for stupid money, thinking maybe the rebuild wasn't as good. No problems, everything seemed perfect.

This week, the alternator died again with an output of 11.9V. I took the truck to 24 different 'specialists' to tell me what the heck is causing the alternators to go out. Nobody can give me an answer, other than "one of the diodes are out, no worries". I replaced it with an OE unit from the yard this time, and the output is 14.4V now.

If it was a mechanical problem, diagnosing it would have been way easier for me. I know next to nothing where electrical issues are concerned, but common sense tells me to get an excessive drain test carried out on the charging system with an AMP meter. I reckon it should be no more than 30 amps at idle, and no more than 60 amp with accessories such as the AC running. The other thing that comes to mind is poor grounding somewhere, but I do not know where to even start looking. What connections should I be looking at? Would an MUT-III help find the problem more easily? Thanks!

PS: Vehicle's a 2000 Pajero/Montero with 173,450 miles.

 

Let us know what you find out because I have been through three alternators since January. I hooked up a voltmeter in the cab to keep an eye on the charging now. It stays right around 13-14, never over 14?? The alternators are autozone reman units. I want to buy an OEM Mitsubishi one, but I want to make sure the problem IS the alternator not the truck before shelling out more money.
I talked to our mechanic about it again the other day when he was over putting the harmonic balancer and pulleys back on and he says it's not the truck, but I just don't know?

 

the main thing that kills alternators on montero's is oil intrusion. v/c gaskets, cam seals are the culprit. if you bought a factory alternator it should still be under warranty, unless it has oil all over it. aftermarket electrical parts do not last long on mitsubishi products, i guess they are just inferior.

 

Thanks for the input guys. My valve cover gaskets and cam seals are still new, never had any problems with those, thankfully. Although the factory alternator I got did not come with a warranty, unfortunately. The dealer does not offer a warranty on any electrical parts whatsoever. I had them install it, so that they offered a 14 day warranty in case their installation caused it to fail, but that was out when the unit died on me.

 

You are not alone. This happened to me and the chain shop replaced the alternator though I feared that they were just replacing a part and not solving the problem. So 7 weeks later and 1016 miles the security system goes off, the car won't start either. Not trusting the chain repair shop I have it towed to the dealer (this is my third Montero). They state the alternator is bad, power going in and no power coming out. Dealer recommends only OEM for twice as much money as the chains remanufactured unit (now units). Yet, when the chain store put the remanufactured alternator in (the one that just went bad) the voltmeter on my dash never registered more than 12 BUT the shop voltmeter showed 14+, but already I am getting the feeling I am draining the battery. After having research the web and focusing just on alternators in general, I really feel I have an open circuit, power drain someplace, and repair shops really do not want to go past the "first error message" so they just change the alternator. The Montero will be going back to the chain repair shop and I will try to keep you posted. I am going to stress to them that we /they need to "work the problem". 3rdMontero