GenVibe - Community for Pontiac Vibe Enthusiasts

Having just gone past 83k miles. I started hearing an odd sound. Very raspy at idle. Then I noticed possibly the charging was weak SOMETIMES. Having attached a voltmeter. Sometimes when the rad-fan kicks on the voltage drops below 13v at idle. I have a nerw battery too. So, I know the battery is good. I think 83k is not a lot. I did remove the belt and spin the alternator by hand. But no sound. Then for a giggles started the car w/o belt...= no bad raspy sound.Could the bearing or brushes if worn make such a noise??? I used a mechanics stethoscope...it oddly seems loudest @alternator..but not massively loud using the stethoscope. Car does see 90% city driving. Again this is problem pof voltage is not all the time. But the sound is always there. Any ideas guys? Is 83k possible bad or worn out.

Vibe alternator failures are uncommon, and 83K miles is low to have an alternator go out. When you replaced the battery, did you clean the battery cable clamps? The factory battery on mine was great, but the aftermarket batteries I've used seem to cause my cable ends to corrode. Doesn't necessarily fit the symptoms you reported, but it is an easy thing to check.

i cleaned everything before the new battery went in 4 WEEKS AGO. I have more tools than most. I replaced the battery because it was the original and 90% of it is w/short trips in city.. And the cranking speed seemed slow to me. Even when warmed up. It cranks quickly now. I have both the new and old battery. Both showed same symptons= low voltage when hot. So it's not a battery issue. I am trained in electronics...and know when things are not operating good electrically. I suspect the voltage regulator is bad...it's internal on these. Below 13v at idle should never happen. And bearings can go bad anytime...so I am told. Which could cause "brush" issues or worse. I suspect the internal regulator is bad. Simply because the issue happens under the hottest conditions. Which is not unusual for a failing electronic part. But I just do NOT know who sells good quality alternators and who does not ? I can get a NEW one not remanf. for $150..REMY brand from Advance. REMY does manufacturing world wide. http://www.remyinc.com/new.aspx" onclick="window.open(this.href);return false; How they make it for so little $$ new is beyond me. FYI- Autozone does not give refunds on any electrical item. Even if it's bad out of the box. So you are stuck with it forever and they might replace it. But never give $$ back if you are frustrated with the quality...So I stay-away from them. ANy knowledge of good or bad brands is helpful. Actually I looked...it's 88k on the old girl.

I don't remember much discussion about the quality of replacement Vibe alternators here. There was a thread where someone had found a higher output alternator, but I don't know if they were any more reliable than the ones from the chain auto parts stores. I tend to buy from Advance instead of Autozone, but that's pretty much because the guys at my local autozone have attitudes, and condescend to be bothered to sell merchandise to peasants like me.


I meant no disrespect to your automotive repair skills.

WOW, THAT'S HOW THEY ACT TOWARDS ME sometimes. I am AARP age. And I know quite a bit about engines. But only 1/2 the staff at the Zone by me is good at helping. At one time they had a great manager. Too bad he's not there any more. But at Advance they are a bit better. And never argue when you bought something that is not made good. I did look up that NAPA has 90 amp rebuilds vs. the 80 amp originals. I see units running from $125 rebuilds to $285...the $285 is a Toyota one I believe new from a large Toyota dealer that sells at a discount, retail is $350+. I am picking up the $150 unit I described in my last posting. Hope it's not a piece of crap from China using old TV parts.HAH. And I suspect REMY supplies the rebuilds to both Autozone and Advance...they are the exact same price and "lifetime" warranty. I have had mnay cars personal and company. This my 1st possibly bad alternator ever. We've "talked" before on other issues. Always good to hear from you.

I would suspect the belt tensioner pulley.
Give it a spin with the belt off.

Measure the AC voltage on the battery with it running.
More than 100mV suggests a bad diode.

Worn out brushes would work intermittently and make the charge light on the dash blink.

The running voltage will be lower at high temperatures. It's temp compensated in modern systems.
But under 13V is a problem.

w/belt off I did spin the tensioner also. It spun smooth...not rough. As for any sound ? nothing significant. I know a new one will be silent. I will have the alternator swapped by saturday. So that should solve the electrical issue. If you read again my post , finding noise using the stethoscope, I Hope it solves both. I think it might. .......I agree...less than 13v should never happen. when only the rad/fan is on.AND WHEN I REVVED the engine it hardly went up. I only saw this when all was "hot".

I have replaced both the alternator and idler pulley. The pulley was not fun. Jacking up the engine and such. Having more tools than God helps. And now I have a normal headed bolt on the pulley for the future. For those who do not know..there's a propriatary bolt on it. A year or so back I replaced the hydraulic piston of the tensioner. So now that's not going to be a problem. Ultimately the noise is not the altrnator, nor idler pulley. AND Testing w/belt off for 20 seconds shows It's not internal in the engine. It's likely the water pump bearing. Note: the water pump does not leak --yet. The reason I could hear the noise @alternator...they are next to each other. And the noise was "ringing through the belt. Unfortunately, Due to other things going on. I cannot change this for a few days. And I can limit driving to just in town. Who would have thought the bearing would go bad, be loud and the pump not leak ? I will give you and update after I change it.

YES, it was the water pump. Changed it today. Truly not a bad job....if you have the correct tools like me. A small quality inch/pound torque wrench should be used. I have a Craftsman(not cheap). Driving the car onto a set of ramps and Removing the lower right splash cover makes this a smooth operation. FYI- 2 of the bolts are difficult to see if you do not. Also 2 bolts are shorter than the others requiring only 80 in/lb...the others are 96 in/lb. My deep socket 10mm cleared the pulley just enough to alow using the toque wrench on all bolts. WHO would have thought a bad water pump bearing would sound like a "box of rocks" ? And the water pump not leak a drop. I think I found a posting of a similar happening...."tensioner or water pump"

ok...THE NOISE WAS THE WATER PUMP...THAT'S FIXED. but TESTING MY ALTERNATOR... the voltage is lower>the warmed the engine is. Do these Denso alternators have a "smart regulator" that helps prevent "over charging"...aka...boiling the acid out? Especially as the engine is warm and running for a significant time? The voltage drops from 14.25 cold first start of the day to 13.5 when it's very warm and running for 30+ minutes. Adding load at idle makes the voltage drop more. But bringing the revs up above 1200 ...the voltage stays 13.5 - 13.6v. The manual says charging voltage is 12.9 - 14.9 volts. To me this is a wide range. Anyone in a warm climate want to do the cold vs. HOT test ??????? . Again these are mostly @700rpm idle voltages. DRL on .

Denso Alternators are stock on the Vibe and Matrix. Solid as a rock. In my opinion, If your water pump went bad dump your coolant and put in Toyota SLLC. You will kill the water pump prematurely using anything else. Don't make the same mistake I did.

Moly enriched coolant (SLLC) = Water Pump Lubricant

The high alternator output during cold start is due to the ECU increasing RPMs. Completely normal to fall a volt or 2 when warmed and idle RPM has dropped below 1k like you have stated. Not really sure about voltage staying put after warm, honestly never messed with any on these cars.

Check the ground wire going to the trans, they tend to corrode there and can cause rough idle and charge issues.

By you saying "kill" , you must mean the mechanical seal. My original water pump SEAL was NOT leaking. But the bearing was making a racket. What antifreeze did you use to KILL your water pump? I changed to "Peak Global" lifetime antifreeze on all my bikes and this car. Did the car 2 years ago. It's SILICATE AND PHOSPHATE free and other positive things too compared to green or orange stuff. This stuff is GOLD...yellow. Yes, the toyota PINK stuff is very good too. But, I never heard of Moly enriched ? I know what moly is...BUT in the coolant is news to me ? >>>That ground wire to the trans. I went far beyond what most would do. I soldered the wire to the OEM lugs at both ends. Did this right when I got the car NEW. I also have other ground wire to the chassis the same. I did it w/o overheating the connectors. It's a thing of beauty. So corrosion between the copper and lug is eliminated. This is common failing point on motorcycles. I knew to do this from the start. But I will look at it to be sure there is no corrosion between lug and tranny. My battery was 7 years old and still tested good...rated 560cca...tested 440.. winter coming, so I replaced it.Yes I know the ECU increases RPM when cold and starting. BUT- I was speaking of all voltages @idle 700rpm. It only takes a few minutes for the idle to drop to 700 after the 1st start. I have a special power plug I use at the dash accessory outlet. This connect to a multimeter. The differentce from read directly at the battery and this accessory plug is less than .1 volt.(1 tenth volt). I just find it odd for this voltage to go down simply from temperature or time on the road...unless these Denso alts. have "smart regulators". Smart means , "it knows the battery if fully charged". Also high voltage charging a battery in HOT temps speeds up the acid loss. The test would be for someone to do as I have and let me/us know if the voltage changes w/time or temps....