If your battery is weak, it will damage your alternator. Make sure that your battery is up to par because this could be the reason your alternators are going bad. This is the first thing to check before you have to go into more complicated checking.

 

Hello.. well reading through your symptoms I have replaced my cam seals and valve cover seals, requires removing the top plenum, not hard if you have a guide and the right tools and basic mechanical talent, i have changed my water pump, timing belt (requires removing the AC radiator if you don't have the right tools to reach or its hard to break free with impact wrench, pulley also requires a special mitsubishi puller or in my case plenty of bolts and steal meccano..lol) I too have changed my starter once due to the oil dripping from the cam seal, new one is fine now that i have removed the seal issue. however i had to put it in the shop after getting an O2 sensor check engine light followed by some weird radio and dash lighting glitches, i have since checked all my wiring and connections and found the culprit and possible cause of your issues, In my case the smaller wire from the alternator to the pos post and on to the fuse box was bad, these engines do get hot! and this wire being thinner seams to weaken faster than the others i suspect a similar breakdown of a fuse box element or inside a wire shielding and replacement required.. also check how secure the main fuse is in engine bay. (worse thing about this issue is just jiggling the wires around while looking for the issue can temporarily fix it until it randomly fails again... in my opinion your issue regarding the flashing instruments etc is main fuse box or secondary (smaller) positive battery post connections and wires.

 

2001 Mitsubishi Montero Sport has a heavy wire going from battery positive to the fuse box next to the battery. It is crimped to a ring connector with another wire that travels to the alternator to 'excite' it and turn it on. There is a 6mm bolt on the corner of the fuse box that attaches the ring connector with the heavy wires (mine were white) to the fuse bus bar. Take off the fuse cover and you will see it right below the 100 amp fuse. Mine was loose and corroded. It got so hot from the resistance that it melted part of the plastic around the connection. I cleaned the connection and replaced the bolt and split washer, as they were pretty corroded also. Once the connection was fixed, my alternator worked great! Make sure yours is tight and clean.

 

I have this problem a couple years ago just make sure there's no oil leaking onto the alternator otherwise it will short out the alternator and you will continue to have all those problems with the above once I change the front head gasket and all the other seals my problem went away

 

Shell- My 01 Montero Sport 3.0 similarly ate alternators at one point. As has been mentioned the problem was bad ground. Wire brushing the body and cable end worked in my case.
Now I'm seeing a different problem. Turning the key just gets a click as would happen with a dead battery. Test indicates 478CCA and 12.95v. Body ground connections still look good but negative battery end cable clamp looks shaky. Working on that. If that doesn't do the trick what's next? Seems like the starter itself is all that's left. Any thoughts?

 

Are you getting power at starter? How big is the voltage drop? In your case, if you're sure you have good grounds to battery, your main positive wire might be the culprit. Check for corrosion at both ends and for internal resistance (possible break/internal corrosion).

 

New starter did the trick. Fires right up with no labor or hesitation. Thanks to all who replied.

 

Shell.......I knew someone else with a Montero wiht the same alternator problems......they had a bad oil leak from the valve cover or end seal that was saturating the alternator with oil, and destroying it. They ended up making a metal shield to put above the alt. to block the oil from getting into it.....like an umbrella in the rain.

 

Just to add a little to the conversation, my 2002 montero sport also eats alternators.. I'm on my third or fourth one now. I bought a replacement in 2019 and then this year I'm having issues so I bought another. Seems as if it's not the alternator though, I am still having some of the surging/stalling (with accompanying low voltage & battery light) problems when the engine is cold that I had before, although not as bad as before I replaced it. My problem has also been there for a while, but previously it was just an annoyance, like a quick one time hiccup. Lately it has gotten much worse and will hiccup fifteen or twenty times and then after it seems to warm up things seem OK.

The reason I'm posting to add to the conversation is that I heard about the oil issue in 2019, and when I pulled this one in 2021 it was literally coated in oil. My rig has 205k miles on it, and loses oil all the time, and honestly I just don't have the time or desire to go fixing a leak that otherwise hasn't been a problem aside from having to add oil every 1k miles. Anyway, the new refurb alternator I bought this year had a notice about the oil leak issue and a plastic shield installed on the back upper half of the unit. Turns out that alternator I just bought had the nut welded in place, and welded wrong so the main alternator bolt would not screw all the way down, and I had to take it back in and get another one. The new one did not have the plastic guard nor the notice. So check for this when you buy a new one! The guys at parts store ended up taking the guard off the one and putting it on the replacement.

Again, I don't think that's my issue, but I'm sure the oil did not help and I'm glad it at least has a little bit of a cover over it. I imagine you could make an even better one as suggested earlier. As for me, I suspect it's a grounding issue and I want to thank everyone who has responded here so far for giving me places to check. I wasn't sure where all the connections might be. If I can find the culprit I will try to come back and post the solution. I believe my battery to be solid. As a side note, my buddy also recommended I replace the spark plugs, since I have not done so in a long time. I bought new ones but I don't intend to replace them until I can solve this issue first, or at least eliminate all the grounding issues as being the root cause.

 

analog.....yep.....looks like MItsu should have made an alternator oil shield at the factory and made it standard on all models.
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