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Post by riverdale21 on Nov 23, 2011 22:01:04 GMT -5
Daily driven 1999 Mitsubishi Montero Sport XLS 2WD 3.0 has gone through 5 alternators in the past two years. As soon as the brake light on the dash comes on it's only a matter of time before it goes out. Google searching reveals this is not uncommon among these vehicles.
With the vehicle running and a Fluke meter connected to the battery reveals a maximum of 12.12 volts DC. I don't want to have to buy another alternator when this one is less that 5 months old.
Other info: 0.1 ohms resistance in negative battery cable to engine block ground and 0.1 ohms resistance in positive battery cable to starter.
I've read that these cars have alternator voltage regulated by the ECU but there is a way to re-wire so it is battery regulated. Anyone familiar with this, or have any ideas why alternators are heading south faster than an octogenarian in the winter?
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Post by bdmontero on Nov 23, 2011 22:52:33 GMT -5
Well the front cam oring seal fails on these and drips oil right on the alternator. Killing them. Also corroded cables and loose battery cable clamps are a problem. The monteros and sports like those clamps butt hole tight.
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Post by riverdale21 on Nov 23, 2011 22:53:57 GMT -5
Other fun facts: New 800ccamp battery, new spark plugs, new plug wires as of 11/20/11.
Voltage measurements were taken on that date when the battery was new. No load (radio disconnected, no dome lights, etc.) after crank voltage crept up to 12.12 after about 10 minutes of run time. Once headlights were turned on it dipped to 11.78 and crept up to 11.88 after 10 minutes. Autozone tested the charging system not long after the new battery install and the battery read 780ccamps and .12v DC alternator charge.
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Post by riverdale21 on Nov 23, 2011 22:59:29 GMT -5
Well the front cam oring seal fails on these and drips oil right on the alternator. Killing them. Also corroded cables and loose battery cable clamps are a problem. The monteros and sports like those clamps butt hole tight. This was suspected after noticing the new alternators were getting coated heavily in oil. This last time the alternator was replaced all new top-end gaskets were done. Valve cover gaskets, spark plug gaskets, valve guide o-rings, and cam seals. This latest alternator still looks clean. I'll double check how tight the terminals are. I bought Autozone + and - cables but they are not long enough and haven't purchased the correct length yet. |
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Post by darkside on Nov 23, 2011 23:21:28 GMT -5
Have you checked the alt fuse?
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Post by riverdale21 on Nov 23, 2011 23:35:11 GMT -5
Have you checked the alt fuse? The 30 amp fuse in the underhood fuse panel? Last I checked it was still good. |
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Post by darkside on Nov 24, 2011 0:21:06 GMT -5
Its on the upper right hand corner of the fusebox under the hood (if your facing towards the passenger side). I think its either 80 or 100 amp.
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Post by riverdale21 on Nov 24, 2011 9:33:12 GMT -5
The fuse box has a battery icon for two fuses a 100amp and a 20amp. Both are intact.
Battery voltage now reading 11.88 with no other load other than running engine. After idling for 30 minutes and revving the engine it went down to 11.52 and the highest rebound was 11.53.
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Post by riverdale21 on Nov 24, 2011 9:44:44 GMT -5
Firewall grounds, chassis and engine block ground all cleaned and torqued down. There is some mild corrosion in the positive battery cable that goes to the starter. That cable read 0.1 ohms resistance. Tracing the smaller line from battery positive leads to post on back of alternator. Resistance 0.1ohms. DC voltage from that post to ground is 11.44v DC. Both battery terminals are torqued down.
Voltage at idle still reads 11.53.
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Post by bdmontero on Nov 24, 2011 15:52:42 GMT -5
I only guess a faulty regulator or alternator. Is the belt loose? Alternators are straight forward. They let you know if their good or bad.
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Post by riverdale21 on Nov 25, 2011 10:52:32 GMT -5
I only guess a faulty regulator or alternator. Is the belt loose? Alternators are straight forward. They let you know if their good or bad. All the belts are less than 7 months old, no cracks, and tension is still good. Had to replace them after the last alternator change. The shop didn't torque the alternator pulley bolt and after about 40 miles fell off the alternator and tore all the other belts with it. I don't get Mitsubishis as far as why the alternators have been such an issue. Granted the first two or three were damaged due to oil and the shop didn't solve the root of that problem until we pointed it out. A new alternator shouldn't look like a 100k+ mile alternator after a few months... I'm going to try replacing all positive battery cables and the negative to chassis/engine ground to see what the result of that is. I don't want to replace the alternator this go around without eliminating the variables. The FSM states that it is a battery referenced voltage so I'll be replacing the Batt + to alternator line as well, just to cover my bases. I'll take voltage measurements at different points and post the results. Hopefully this will help other people having the same issue. |
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Post by riverdale21 on Nov 25, 2011 11:04:35 GMT -5
Oh yeah, also tested the battery relay for functionality with a 9v battery. Clicks and has continuity.
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Post by riverdale21 on Nov 25, 2011 21:54:53 GMT -5
Ok, replaced all battery cables, and alternator cables. It definitely needs an alternator at this point. Still not charging. My thought is due to corrosion the alternator was having to work double time causing it to burn up.
Going to Advance tomorrow to charge the battery and test the alternator/buy a new one. Hopefully with all new cables and no more oil leaks this one will actually last.
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Post by andy28 on Jan 6, 2012 0:42:21 GMT -5
please let me know what you find out, i have the same problem going to be my 4 altenator and just today battery and break light are on
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