was wondering if anyone has done an alternator overhaul, more specifically, replaced the brushes. I suspect the diodes are not serviceable as in past vehicles, I have seen that they are "brazened". Not even sure there are replacement kits for brushes available but was wondering in general. Voltage output looks OK and responds to charging "effort" but "suspicion" point to lack of sufficient current production resulting in overall poor charge performance. I haven't taken it off yet to see if it can be readily cracked open but I assume since they have "core charges" that it can be readily "remanufactured" so the possibility of some form of "overhaul" may be possible and beside contact cleaning, brushes would seem like the best thing to focus on.
alternator overhaul... ?
- Thread starter budwich
- Start date
doesn't appear to be an "overhaul option" available anywhere outside of a "half body replacement" (ie. the electronics body half). :-( Oh well, have to keep an eye on things to see if conditions change.
HARDTRAILZ
Moderator
- Nov 18, 2011
- 49,665
I have not seen a kit. When I needed an Alt it was cheap enough I just bought a reman off ebay with no core charge.
it would appear that will ultimately be the best direction. I will likely take the existing one off and apart just see if there is something obvious that may be correctable with some tlc. thanks
AtlWrk
Member
- Dec 6, 2011
- 674
Like this:
https://alternatorstarterrebuildkits.com/product/ad244/
They have a few different kits and I can't say this particular one is applicable to you but it's 1/4 the cost of a reman from a retailer.
https://alternatorstarterrebuildkits.com/product/ad244/
They have a few different kits and I can't say this particular one is applicable to you but it's 1/4 the cost of a reman from a retailer.
ooookkkkk. that's kind of in-line with my thinking. Bearing don't seem to be an issue although that might change once I get the thing out / apart. Guess the question is: how does one know what actual alternator number / code they have... where is it stamped / marked?
having said that, the link provided shows 2002-2006... mine is 2008 so maybe another kit... hmmm, probably unlikely as the later years use the "variable voltage" thing. :-(
Ok... found one going thru the site..... thanks
having said that, the link provided shows 2002-2006... mine is 2008 so maybe another kit... hmmm, probably unlikely as the later years use the "variable voltage" thing. :-(
Ok... found one going thru the site..... thanks
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AtlWrk
Member
- Dec 6, 2011
- 674
There's a lookup function on their homepage but for expediency, here's the 2007-2009 kit:
https://alternatorstarterrebuildkits.com/product/dr442pin/
https://alternatorstarterrebuildkits.com/product/dr442pin/
HARDTRAILZ
Moderator
- Nov 18, 2011
- 49,665
I think it was like $75 for my new one and it was 180 Amp. Came with a test sheet to show exactly what it did.
littleblazer
Member
- Jul 6, 2014
- 9,265
There are none that I have seen as far as kits but like was said, a new one is cheap enough that I don't feel it's worth the hassle.
I will tell you from my experience. Don't try to change the bearings out by just pressing them out. The one in the front cover of the alternator (closest to the pulley) has a little lip over the outside bearing race and it prevents you from pressing the bearing out without cracking the casing. The only way to get the bearings out is to cut the little lip that they molded around the bearing away and then you can press it out and reinstall a new one with some loctite to keep it into place. This is true for both the large front bearing and the small rear bearing on the alternator. Pulling the bearings is the biggest pain in the ass ever.
The diodes are not not replaceable as an individual assembly. The diodes are spot welded to the bridge rectifier like a buss bar setup. The stator is soldered with 3 wires to the bridge rectifier and then bolted to the case of the alternator with bushings to prevent a short to ground (case of alternator). If you want new diodes you would need to get it as an entire bridge and bolt it on then solder it to the stator wires.
Unless you are really demanding your alternator i'd only put maybe a smaller pulley on your alternator so that it can spin a bit faster and get better output at a slower engine speed however that comes at a cost. The smaller pulley you put on the alternator the lower you need to keep your engine speed or you will overdrive the alt and risk blowing it up. I have a 250A mechman alternator on my envoy and if I rev the engine anything above 5k RPM's it will shut off the alternator since it's spinning way too fast. I have a smaller pulley on my aftermarket alternator to help it provide better output at idle and because of that it spins the alternator faster than the OEM pulley size will.
The diodes are not not replaceable as an individual assembly. The diodes are spot welded to the bridge rectifier like a buss bar setup. The stator is soldered with 3 wires to the bridge rectifier and then bolted to the case of the alternator with bushings to prevent a short to ground (case of alternator). If you want new diodes you would need to get it as an entire bridge and bolt it on then solder it to the stator wires.
Unless you are really demanding your alternator i'd only put maybe a smaller pulley on your alternator so that it can spin a bit faster and get better output at a slower engine speed however that comes at a cost. The smaller pulley you put on the alternator the lower you need to keep your engine speed or you will overdrive the alt and risk blowing it up. I have a 250A mechman alternator on my envoy and if I rev the engine anything above 5k RPM's it will shut off the alternator since it's spinning way too fast. I have a smaller pulley on my aftermarket alternator to help it provide better output at idle and because of that it spins the alternator faster than the OEM pulley size will.
I agree... I wouldn't attempt any bearing replacement as even in past vehicles, the bearing "effort" was substantial. Spinning the alternator doesn't appear to indicate any mechanical issue.
I continue to monitor the voltages continuously (via a lighter plug-in display). Reading up more on the charge system "semantics", it would appear the regulated voltage control system (RVC) "thinks" it needs to be in some form of "battery sulfation mode" as the voltage is relatively high 14.7-15.0 for a period of time then proceeds to drop thereafter to somewhat normal levels (13.8-14.1).
The battery is new (manufactured in sept).
I haven't removed the alternator for inspection yet as its darn cold... not sure when that might be achieved.
New question though.... Have people seen failure / replaced the SARVC block at the negative pole / cable? It appears to provide some of the 5V modulation signal towards the charge system / pcm which ultimately feeds this back towards the alternator.... if my read / understanding is correct.
The cable appears to be a cheaper focus point of repair than the alternator which seems to be responding in general as I don't see things like dimming lights..... although the effort in changing out the cable might be more severe in the current climate...
Further to the RVC operation, my vehicle sees multiple state of charge (SOC) events (key off for more than 24hours) which again, if I read the RVC operation, if the module has issue, then perhaps its readings of SOC suck... and the charge system / control ain't so good.
Although the cables / contact look good maybe some further cleaning is needed.... certainly can't hurt...
I continue to monitor the voltages continuously (via a lighter plug-in display). Reading up more on the charge system "semantics", it would appear the regulated voltage control system (RVC) "thinks" it needs to be in some form of "battery sulfation mode" as the voltage is relatively high 14.7-15.0 for a period of time then proceeds to drop thereafter to somewhat normal levels (13.8-14.1).
The battery is new (manufactured in sept).
I haven't removed the alternator for inspection yet as its darn cold... not sure when that might be achieved.
New question though.... Have people seen failure / replaced the SARVC block at the negative pole / cable? It appears to provide some of the 5V modulation signal towards the charge system / pcm which ultimately feeds this back towards the alternator.... if my read / understanding is correct.
The cable appears to be a cheaper focus point of repair than the alternator which seems to be responding in general as I don't see things like dimming lights..... although the effort in changing out the cable might be more severe in the current climate...
Further to the RVC operation, my vehicle sees multiple state of charge (SOC) events (key off for more than 24hours) which again, if I read the RVC operation, if the module has issue, then perhaps its readings of SOC suck...
and the charge system / control ain't so good.Although the cables / contact look good maybe some further cleaning is needed.... certainly can't hurt...
cleaned up the ground near battery... it was good to begin with. Anyways, unplugged the sarvc module, started the vehicle, alternator starts and stays at ~13.7 which is the default operation when the sarvc is disconnected. Based on that, it would appear that the alternator and PCM are operating "appropriately". It seems that perhaps the sarvc has an issue. Not sure if they are independently replaceable although I am able to partially remove it from the negative terminal connector. There appears to be a some form of plastic cable strain relief /cable "clamp" on one end that helps maintain contact with the cable bundle. Rockauto shows a whole negative cable with sarvc module but doesn't appear to carry just the module.
lots of "search fun" with this...
so the module only (gm part number 25826405) is available for $80-100 (plus tax, etc) from various sites. On rockauto, from the picture is appears you can get the whole negative cable and module for $60-70 (all in) although they don't specifically list the module in the description and don't show the module seperately. Tracing back the negative cable to "somewhere" seems like fun especially in cold with brittle cable "flex sheath".
so the module only (gm part number 25826405) is available for $80-100 (plus tax, etc) from various sites. On rockauto, from the picture is appears you can get the whole negative cable and module for $60-70 (all in) although they don't specifically list the module in the description and don't show the module seperately. Tracing back the negative cable to "somewhere" seems like fun especially in cold with brittle cable "flex sheath".
Mooseman
Moderator
so I order a cable (including the module) off amazon.com ... canadian eh... not sure when it will get here although they list 2nd week in january ... :-(
I did also talk with a wrecker / salvage, no luck as they basically rip out most electrical (large cable stuff) and salvage as copper.
Anyways, I might run with the module disconnected to prevent overcharging although short periods of "high" voltage at startup hopefully won't harm the battery... hopefully.
I did also talk with a wrecker / salvage, no luck as they basically rip out most electrical (large cable stuff) and salvage as copper.
Anyways, I might run with the module disconnected to prevent overcharging although short periods of "high" voltage at startup hopefully won't harm the battery... hopefully.
littleblazer
Member
- Jul 6, 2014
- 9,265
I mean my multi bank boat charger hits the batteries with 15 volts for periods of time.... I think you'll be fine.
this is one of the better documents that I came across on how the system works in general, hopefully most of it applies to trialblazers.
http://acdelcotechconnect.com/pdf/imtn_V12I305.pdf
http://acdelcotechconnect.com/pdf/imtn_V12I305.pdf
well... happy easter. I finally got around to changing out the negative cable along with the SAVRC module which is "somewhat an integral part" (not really as it is held on by tape and plastic cable ring). Anyways, getting the darn old cable out of the plastic wire looms that runs along various points of the path was a "b@#$%"... along with forcing the new cable back in... not much room anywhere as other cabling occupies most of the hand space.
Anyways, it appears the replacement SAVRC module is the solution. The old unit seemed to always want to go to "desulfate mode" (14.8-15) on the battery after start up. Not sure why. The new SAVRC seems to sit at the normal 14.2 charging at startup... I haven't run long enough to see if it does the "usual drop voltage" mode once a "steady load / charge" has been reached. Will continue to monitor to see if everything is functioning as expected. Outside of some of the information I came across (linked), not sure how the system determines the various modes and when and for how long it should be in them.
Certainly glad I was able to pick up the cable and module of amazon for less than $40 especially since the module itself is usually selling for $100 or so.
OOPS... I thought I had attached a link earlier to some info that I had found... I didn't ... so here it is. It is somewhat dated but I think it gives good background to the overall system.
https://acdelcotechconnect.com/pdf/imtn_V12I305.pdf
Anyways, it appears the replacement SAVRC module is the solution. The old unit seemed to always want to go to "desulfate mode" (14.8-15) on the battery after start up. Not sure why. The new SAVRC seems to sit at the normal 14.2 charging at startup... I haven't run long enough to see if it does the "usual drop voltage" mode once a "steady load / charge" has been reached. Will continue to monitor to see if everything is functioning as expected. Outside of some of the information I came across (linked), not sure how the system determines the various modes and when and for how long it should be in them.
Certainly glad I was able to pick up the cable and module of amazon for less than $40 especially since the module itself is usually selling for $100 or so.
OOPS... I thought I had attached a link earlier to some info that I had found... I didn't ... so here it is. It is somewhat dated but I think it gives good background to the overall system.
https://acdelcotechconnect.com/pdf/imtn_V12I305.pdf
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