1997 Mitsubishi Montero Fails to start on hot days

1997 MITSUBISHI MONTERO
71,000 MILES • 6 CYL • 4WD • AUTOMATIC
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XAVIERP
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Last summer around July of 2007 on a hot day I came back to my car after some quick shopping at the mall (aprox. 45min later) for a pair of shorts thinking I was going to go to the beach! Proceeded to turn the key but all I heard was a weak sound as if the starter lacked enough juice to crank the engine. I then cleaned the battery & cable terminals which had built some sulfur, hooked it back & voila! the engine started but then it reved down & shut down again. I then started the engine again but had to keep my foot on the gas so engine won't rev down and stall. Drove back home like this. (NOTE: I noticed that the car was anemic). Next day I took the car to Strauss repair. They indicated the car needed a tune-up & that one cylinder was mis-firing which is why the engine was weak. Picked up car the next day. They indicated that all electrical cables (except battery cables) were changed. Idling problem was gone but car was still weak. Surprisingly the car recouped it's power after a few days. I enjoyed the rest of my summer. Fast forward to May 08 & again on a hot day I came back to my car and same thing. The truck failed to start I checked battery terminals which again had formed white sulfur powder. I once again cleaned terminals, car was able to start but wants to rev down. I managed to take it to a mechanic who connected a volt meter to battery while car was running and it clocked-in at 12 Volts exactly. He said it needs new battery. I find it hard to believe this because every time after I clean the terminals it starts although it wants to rev down. Battery cables for this car are very expensive (about $120 for both) so if It's not the cables I wouldn't like to replace them.

Please shed some light.

Thanks in advance!

Xavier
May 18, 2008 at 4:36 PM
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MASTERTECHTIM
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first of all i apoligize for not responding quickly. your vehicle needs a new alternator in my opinion. the first tell tale sign is the weak battery. second when the mechanic checked the battery system with the car running he got 12v. no good. he should have read about 14v running and atleast 12.6 with it off. by this time your battery may well be bad but i think its caused by a faulty alternator not charging it. hope this helps and repost if you need further assistance
May 21, 2008 at 5:45 PM
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XAVIERP
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Dear mastertechtim,

Thanks for your response. I'm having a bit of a hard time agreeing with your diagnostic because the car wouldn't have started after just cleaning the terminals... How about the idle problem? Will a faulty alternator cause the car to want to rev down and die?

I do understand that you can do only so much without actually looking at the car but a faulty alternator in this case doesn't make much sense to me.

Let me know what you think.

Thanks!
Xavier
May 22, 2008 at 10:07 PM
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MASTERTECHTIM
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if you already cleaned the battery terminals and they are tight. i can only assume they are clean and tight. the vehicle is running and you are geting 12v at the battery. this means for a fact that the vehicle is running off the battery charge and not on the charging system like it should be. moving the terminals at the battery is doing one of two things, making the connection or giving you a little more juice by taking the extra time for the battery to regain a little more charge. the key here is 12v at the battery when the vehicle is running. this much we know without doubt is wrong and needs to be corrected. if you correct this problem by either replacing the alternator or really fixing the battery terminals, i think your problem will be solved. get back to us
May 23, 2008 at 6:14 AM