Catera 3.0L V6 with Bosch 120A, Low Voltage on Idle
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Cadillac Catera and Cimarron Forum Discussion, Catera 3.0L V6 with Bosch 120A, Low Voltage on Idle in Past Cadillac Vehicle Discussion; I was having issues with my Cadillac Catera 2001 3.0L V6 which is a version of the equivalent Omega. I ...
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    USEDCAT is offline Cadillac Owners Fanatic
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    Catera 3.0L V6 with Bosch 120A, Low Voltage on Idle

    I was having issues with my Cadillac Catera 2001 3.0L V6 which is a version of the equivalent Omega.

    I checked performance curves for Bosch for my alternator by duly reviewing the pulley ratios for crankshaft and alternator pulley. The standard Idle on my engine without Aircon on is 500RPM and with Aircon on it is 625RPM.

    As can be seen with the attached chart the Alternator/Generator delivers virtually no amps and if you have idle at 500RPM and got your accessories and it is a hotter day you will see the voltage start dropping on extended idle or stop and go.

    I installed a 1.7" pulley (nominal 1 3/4") versus the standard 2.21" (nominal 2 1/4") and the curve shows how it will help stabilize the electrical load versus generation. The chart Axis are Y-Axis Amps output of alternator and x-Axis is the Engine RPM. To not confuse I have converted x-axis to engine RPM whereas Bosch charts show the Alternator RPM.



    It clearly shows that for my Idle conditions will improve as follows,

    Idle no-Aircon at 500RPM ---> From 0 Amp to almost 35 AMP+
    Idle with Aircon at 625RPM --> From ~ 40 AMP to ~80 Amp

    Any comments as I believe it may rob a little bit of power (haven't noticed any and car is very happy).

    Hope it is of help or generates ideas.

    PS: To compensate for smaller pulley I used a slighly shorter Auxiliary Drive Belt to ensure good tension with the auto tensioner and the following part number,

    Gates Part Number: K060790
    Interchange Part Number: 6PK2005

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    retho78 is offline Cadillac Owners Connoisseur
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    Re: Catera 3.0L V6 with Bosch 120A, Low Voltage on Idle

    Where did you get the belt tensioner pulley and belt from?

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    USEDCAT is offline Cadillac Owners Fanatic
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    Re: Catera 3.0L V6 with Bosch 120A, Low Voltage on Idle

    Quote Originally Posted by retho78 View Post
    Where did you get the belt tensioner pulley and belt from?
    Pulley and belt from eBay as follows,

    Pulley: http://cgi.ebay.com/ebaymotors/ws/eB...m=190399813071

    Belt: http://cgi.ebay.com/ebaymotors/ws/eB...m=330408572862

    The belt I think will be pretty standard to get with the Gates number.

    The pulley instructions are not 100% correct and I ended up not using couple of their washers.

    Getting the pulley off the alternator not such a sweet deal if you want to do with the alternator in place. I just destroyed the original pulley while holding the pulley with a wrench (auxiliary belt off the pulley) and then unscrewing the holding nut. One good thing is that pulley is not force fit on the shaft and just slides off when the nut comes off.

    I am a moderate driver and my revs are generally not too high for city or highway driving. If you going to be doing the redline on RPM in your vehicle I would not do this mod as the Alternator revs will get too high and possible damage.

    Cheers.

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    retho78 is offline Cadillac Owners Connoisseur
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    Re: Catera 3.0L V6 with Bosch 120A, Low Voltage on Idle

    thanks. I thought the pulley was for the belt tensioner. After reading your post and looking at the pictures I noticed that it was for the alternator.


    Thanks.

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    Re: Catera 3.0L V6 with Bosch 120A, Low Voltage on Idle

    I have this same issue as I can see it when all the interior instrument lights dim and the wipers work slower than normal, I was thinking to send my alternator out to Iraggi Alternators and they can rebuild it with an output of 240 AMPS.

    http://cgi.ebay.com/ebaymotors/240-A...Q5fAccessories

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    USEDCAT is offline Cadillac Owners Fanatic
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    Re: Catera 3.0L V6 with Bosch 120A, Low Voltage on Idle

    Quote Originally Posted by TitanCTS View Post
    I have this same issue as I can see it when all the interior instrument lights dim and the wipers work slower than normal, I was thinking to send my alternator out to Iraggi Alternators and they can rebuild it with an output of 240 AMPS.

    http://cgi.ebay.com/ebaymotors/240-A...Q5fAccessories
    My friend I tried to buy a high amp alternator too. A very wise man who actually rebuilds and sells these told me when I explained my idle juice shortage, he said actually the high amp alternators are going to be no help and may even make it worse. The high amps are not any better at idle RPM. The basic issue with all the alternators is at which RPM they kick in. Most don't produce anything or much at the standard idle of 500 RPM and with the AC on and RPM at 625, the extra fans kick-in and we get in bad situation again.

    He suggested the pulley being the best way to address it. Even though at the end of the day I did not buy the pulley from him.

    Just in case it helps.

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    Re: Catera 3.0L V6 with Bosch 120A, Low Voltage on Idle

    Ya that makes sense.. Another issue with my charging system is when I'm on the highway for a while 30min- 1hr with A/C on and really hot out the volt gauge gets really low to the one line right before the red zone, So I don't know if the voltage regulator is crapping out or it's just an excessive load with high temps, I tested the alternator a while ago and it came out ok, So who knows, I might try the pulley trick and see if that helps.

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    USEDCAT is offline Cadillac Owners Fanatic
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    Re: Catera 3.0L V6 with Bosch 120A, Low Voltage on Idle

    Quote Originally Posted by TitanCTS View Post
    Ya that makes sense.. Another issue with my charging system is when I'm on the highway for a while 30min- 1hr with A/C on and really hot out the volt gauge gets really low to the one line right before the red zone, So I don't know if the voltage regulator is crapping out or it's just an excessive load with high temps, I tested the alternator a while ago and it came out ok, So who knows, I might try the pulley trick and see if that helps.
    I believe you were driving my car LOL.

    I also had the same situation with low oil pressure on top. To keep the revs up in stop and go on the highway I turned the AC on to keep oil pressure stabilized. The battery/charging started to do per your post. I found myself really between rock and a hard place.

    I have done two changes noting these issues from last year.

    1) Oil pressure addressed so far by installing a new Oil Pressure Sensor that controls both the gauge and low pressure light. So far so good but havn't seen extreme hot temps yet. Pretty confident that issue is gone though.

    2) To address two much battery drift on idle to the point that you turn the fan on max and the battery needle would start to move down significantly. I have done the overdrive pulley mod. Again it appears to have stabilized and improved things. If the whole summer lasts without any issues I will say my solutions have worked. Changing the serpentine is a little bit of a pain. You need to get under the car and remove the plastic cover below the crankshaft/pulleys area and undo couple of bolts to remove and replace the belt. Remember also that if you use smaller diameter pulley you will need an equivalently shorter serpentine as identified for my mod in my post.

    Cheers.

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