Renix alternator problems

Ecomike · Jan 10, 2009

Usually it is obvious to me when an alternator goes bad, but mine is coming and going, so I have a what happened question here for 5-90 and the EE guys.

About 2 weeks ago I ran through a puddle of rain water that was just deep enough that it splashed the alternator (I have no splash guard). The belt slipped for a few seconds, and then everything was back to normal. I wondered at the time if my alternator might give me trouble. Well a week ago I noticed my dash gauge voltage was lower than usual. I checked the battery voltage, OK, Bat voltage with engine running OK, same with head lights, AC and AC blower motor on high and Max, the Bat voltage dropped to about 12.70 volts, from a bit over 14 volts, so I figured I had lost half the diodes. An hour later I started it up and the voltage and current was normal again during my next trip(s). Stayed OK for last 5 of 7 days and acted up again last 2 days.

Had the battery load tested at Auto zone today while it was acting up, battery is OK. So I am wondering if the voltage regulator is acting up (In Renix it is built in to the alternator) or if I have an intermittent set of diodes that got heat /cold water shocked and are now making intermittent contact inside or outside of the diode set, and thus are working one minute and then not the next.

I am replacing the alternator right now, but curious as to everyones thoughts on it. In the past my alternators have always died 1/2 way and then all the way as one diode set then another burned out, or got fried jump charging another car.

Saudade · Jan 10, 2009

Not sure about our beloved Renix. My Nissan P/U developed a charging problem that caused my Charge lamp to glow very dimly. My battery voltage running was nearly 14v so all looked good. After a few days of running, my battery would die and not start. A quick charge or jump and it was good. I finally took it off and had it tested and the results said the diodes failed (also internal). Put on a reman alt and all is good again.

Ecomike · Jan 11, 2009

Well I swapped out the alternator with a used one that Autozone bench tested as a 75 amp model, that tested OK. It is working better than the one I pulled off, but it is still a little shy of the amps needed at peak load, and is dropping to about 12.95 volts with everything on. Turns out the one that died was a 100 amp, so with half the diodes acting up it was giving me 50 amps max. I did not hear any noise on the jeep running, put the bad 100 amp unit I pulled had a squeaky bearing noise when turned by hand so Autozone warrantied it for free after 2-3 years of use! NICE!

Strange but when they bench tested it as a 100 amp version it tested OK on the bench load tester. But it would come and go the past week too on my rig, and the bearing noise was enough for them to replace it for free.

Now I get to pull the spare and swap it again, "Oh Bother said Pooh"!

Now I am wondering why Jeep used a 75 and 100 amp alternator. Perhaps the 75 amp was for non AC rigs?

I am guessing the bearing noise and peak output coming and going was the early failure warning signs and I just caught it early.

8Mud · Jan 11, 2009

Ecomike said:
Well I swapped out the alternator with a used one that Autozone bench tested as a 75 amp model, that tested OK. It is working better than the one I pulled off, but it is still a little shy of the amps needed at peak load, and is dropping to about 12.95 volts with everything on. Turns out the one that died was a 100 amp, so with half the diodes acting up it was giving me 50 amps max. I did not hear any noise on the jeep running, put the bad 100 amp unit I pulled had a squeaky bearing noise when turned by hand so Autozone warrantied it for free after 2-3 years of use! NICE!

Strange but when they bench tested it as a 100 amp version it tested OK on the bench load tester. But it would come and go the past week too on my rig, and the bearing noise was enough for them to replace it for free.

Now I get to pull the spare and swap it again, "Oh Bother said Pooh"!

Now I am wondering why Jeep used a 75 and 100 amp alternator. Perhaps the 75 amp was for non AC rigs?

I am guessing the bearing noise and peak output coming and going was the early failure warning signs and I just caught it early.

This is a good read. http://www.alternatorparts.com/cs130_sbpage3.htm

An 88 Chev P.U. alternator is a bolt in. And all I've seen are the 105 amp variety. And often cheaper than the Jeep, at least a round here. Though I do seem to remember the rib count beg different on the belt (pulley), I may be wrong it's been awhile.

Your problem could have been as simple as a dirty slip ring. I've had the back off of numerous alternators and cleaned the slip ring up, which restored function. The design of the brushes and the slip ring, doesn't, scrub/self, clean well at all, the buildup just stays there and gets worse.
The outcome loosing a diode in the CS type alternator, really depends on which diode goes. Though most people seem to agree the regulator is often the culprit, I really can't remember seeing more than one or two go bad in the last 25 years or so. One problem I've seen more often is coolant coating the insides of the alternator and partially gorounding the regulator and other componenets. Usually a slow and intermitant death with eventual total failure.

5-90 · Jan 11, 2009

You can also find a local rewind shop, and get your unit uprated. 130-140A is common, 180-200A is possible (mine is rated for 175A, and peaks at 198A.)

Of course the alternator tested fine on the bench at AZ - how many times do I have to say this? "The chain store benches test voltage output, not current. They check for 13.0-14.0VDC at not quite enough to drive a good flashlight bulb..." You're seeing a test of some 12VDC nominal (on the bench) at about 0.8-1.2A. The red BEAR ARBST? I don't trust those, either. The are - just a bit! - better than the bench inside, tho.

The local rewind shop probably has a bench that you can see about half of (under all the parts,) looks like something out of Viktor von Frankenstein's lab (I know my shop's bench looks like that,) and can wring out your alternator properly. Rod can toss an alt up on his bench, and tell you exactly what's wrong with it in about thirty seconds. Give him two minutes, and he'll know exactly what it can do at peak, how long you can hold it there, how much ripple makes it through, ...

If you splash mud into the case, you need two tools to clean it back out - a 5/16" nutdriver and a toothpick. The nutdriver is to take out the through screws, the toothpick is to hold the brushes in the holder while you put the case back on. The case back comes off easily, and you can change the regulator, the diodes, and/or the brushes once you're in there. The slip rings can be easily cleaned up with a wind of emery cloth. Cleaning the rest is a simple application of your favourite electrical contact cleaner (and I do miss trichloroethane. It worked very well, and I didn't need anywhere near as much of it!)

Ecomike · Jan 11, 2009

5-90 said:
You can also find a local rewind shop, and get your unit uprated. 130-140A is common, 180-200A is possible (mine is rated for 175A, and peaks at 198A.)

Of course the alternator tested fine on the bench at AZ - how many times do I have to say this? "The chain store benches test voltage output, not current. They check for 13.0-14.0VDC at not quite enough to drive a good flashlight bulb..." You're seeing a test of some 12VDC nominal (on the bench) at about 0.8-1.2A. The red BEAR ARBST? I don't trust those, either. The are - just a bit! - better than the bench inside, tho.

The local rewind shop probably has a bench that you can see about half of (under all the parts,) looks like something out of Viktor von Frankenstein's lab (I know my shop's bench looks like that,) and can wring out your alternator properly. Rod can toss an alt up on his bench, and tell you exactly what's wrong with it in about thirty seconds. Give him two minutes, and he'll know exactly what it can do at peak, how long you can hold it there, how much ripple makes it through, ...

If you splash mud into the case, you need two tools to clean it back out - a 5/16" nutdriver and a toothpick. The nutdriver is to take out the through screws, the toothpick is to hold the brushes in the holder while you put the case back on. The case back comes off easily, and you can change the regulator, the diodes, and/or the brushes once you're in there. The slip rings can be easily cleaned up with a wind of emery cloth. Cleaning the rest is a simple application of your favourite electrical contact cleaner (and I do miss trichloroethane. It worked very well, and I didn't need anywhere near as much of it!)

Autozones new machines do run three separate tests. The third is an actual load test supposedly :dunno: at the rated amperage. They enter the actual model number into the computer before the test will run which tells it in part what load to put on it. I have watched them run the load tests. But it does not list the load or voltage, just a passed or failed value. My last one that went out about 4 months ago, (on the other jeep) failed at about 50 amps peak output IIRC, on their tester, the same values I got with my 2 bit test method on the jeep.

5-90 · Jan 11, 2009

Ecomike said:
Autozones new machines do run three separate tests. The third is an actual load test supposedly :dunno: at the rated amperage. They enter the actual model number into the computer before the test will run which tells it in part what load to put on it. I have watched them run the load tests. But it does not list the load or voltage, just a passed or failed value. My last one that went out about 4 months ago, (on the other jeep) failed at about 50 amps peak output IIRC, on their tester, the same values I got with my 2 bit test method on the jeep.

Sounds like they're supposedly improving (I'll put more faith in Rod's bench than anything at a chain - I know he's wringing the thing out. And it's not just a "pass/fail" with him. As I said, by the time he's done with it you know exactly what it can do!)

Ecomike · Jan 11, 2009

5-90 said:
Sounds like they're supposedly improving (I'll put more faith in Rod's bench than anything at a chain - I know he's wringing the thing out. And it's not just a "pass/fail" with him. As I said, by the time he's done with it you know exactly what it can do!)

I have a real professional local shop here too, same story, used them recently for my special Nissan diesel engine alternator which has an oil bathed rotary vane vacuum pump on the rear of the alternator. Could not find any ready to install in stock in the USA late last year, so I had him rebuild mine. Finally got a spare from a guy in Canada last week.

I must admit the pass or fail data output is not impressive at all.

Renix alternator problems

Ecomike

NAXJA# 2091

Saudade

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Ecomike

NAXJA# 2091

8Mud

NAXJA Forum User

5-90

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Ecomike

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5-90

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Ecomike

NAXJA# 2091

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