InfernoX90

Alternator?

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I think i read somewhere in the forums that a 89 reatta should run about 14v+, i recently had to change a alternator cause it was reading in the 11v range, and now it reads 13-13.5v with not load going down a road with no load, but as soon as a load is put on it, it drops to the 12v range, and when it comes to a stop it will go as low as 11.9v with a load and 12v without a load at idle.  Is it safe to assume this reman alternator is no good? The battery is only a few months old also.

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Assume nothing until you put a meter on the battery, first with engine off to check battery-should be 12.5-12.7v on hot battery, then crank it up and check idling, should be in the 13.5v range. Turn on lights and heater blower and recheck to see if it holds at or above base battery voltage of 12.5. Volt meter in dash may show low like my '88 olds which only shows appx 12.9 on highway.

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13.1-13.4 is normal for 1200 rpm up. 12.6 min at idle. Below I would be concerned.

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while checking the battery for voltage - (you may want to check it with a multi-meter or separate voltmeter to make sure the readings are about the same as your vehicle's voltmeter shown on the CRT) - make sure the battery cables are clean and tight. 

 

i'd also check these grounds: http://reattaowner.com/roj/component/content/article/62-electrical-system/other-electrical/224-ground-terminals-junction-box-location

 

just because the grounds are tight and appear clean, that doesn't mean there isn't any corrosion between the ground bolt(s) and connection(s).

 

re: the alternator - since my Reatta was a daily driver at the time, i couldn't wait to order one and went up to a FLAPS and bought a rebuilt alt. it went out after 3 or 4 weeks. it was still under warranty, so i went back to the FLAPS, they put it on their machine and it showed it was bad - got another one at no charge (keep your receipts!). idk if it makes a difference or not, the first bad alt was made in China. the second good one was made in Mexico :unsure:...

 

my voltmeter wound show 14.2 or so at start up, then settle in the 13's...

 

hope this helps! :)

Edited by Corvanti (see edit history)

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Volts sound about right. My dash readout is always less than at the battery. Are two alternators that fit the Reatta: the CS 130 (plug wires fit underneath and the CS-144 (they don't). CS-130s last months, 144s years.

 

I had a 140A CS-144 in my RV and it handled everything even at idle.

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