What did you do to your NNBS GMT900 Tahoe/Yukon Today?

[iamdub]

yeah I didn't really expect to clean all that, just unscrew the bottom and dump it from time to time. I just wasn't sure where to put the steel pad if I was to use it lol.

That's a different design than the more common ones. Those have a ~2.5" plate with holes all in it (the baffle) that's suspended about 1" below the top piece. The scrub pad would go in that 1" gap, basically resting on the baffle like a shelf. There's usually some polymer sponge material, like the green or rust-colored scrub pads packed in that smaller area behind the baffle. My catchcans.com one has this as well as the scrub pad that I added. There's no reason to disassemble and clean it. Just drain it. If the material is thick enough, I'd drill and tap a hole in the bottom to screw in a drain valve. Or, if it's too thin, drill it and TIG a nut to the bottom to screw in a drain valve. Trim the threads of the valve to not protrude higher than the floor of the reservoir so it drains fully.

 

[iamdub]

I would hope that the alternator you bought and modded has more modern circuitry. I'm also not sure how much of the charging process is controlled by the ECM/BCM vs the IC's in the alternator itself. Hence why it's still just a theory based on observations from 3 pre-AGM vehicles.

I'm not 100% sure, but I think the alt's output regulation is controlled by a PWM signal from the PCM. It's not an "on/off" signal. It may not be PWM, it could be a reference voltage scale. Whatever it is, GM, apparently, kept the same control design on the succeeding generations. Looks like I have researching to do.

 

[iamdub]

Last Thursday, the kiddo and I went to hang with the Texas fam at a beach house VRBO in Galveston. Terramar Beach, to be specific. Spent Friday and Saturday on the beach and drove home Sunday.




That bird's lookin back like "to shit or not to shit?"





Last night, I took McKinley to a concert in New Orleans. This is the second year in a row that she's requested to see live music for her bday present. I couldn't say 'no' to that! Her bday is over a month from now, but she wanted to see Pixies. Franz Ferdinand and Bully opened for them. I've never heard of Bully and had forgotten how cool Franz Ferdinand is. They had great energy and put on a good show. Oh- what I did to my GMT900... I parked it as safe as possible in a paid parking garage:

 

[j91z28d1]

That's a different design than the more common ones. Those have a ~2.5" plate with holes all in it (the baffle) that's suspended about 1" below the top piece. The scrub pad would go in that 1" gap, basically resting on the baffle like a shelf. There's usually some polymer sponge material, like the green or rust-colored scrub pads packed in that smaller area behind the baffle. My catchcans.com one has this as well as the scrub pad that I added. There's no reason to disassemble and clean it. Just drain it. If the material is thick enough, I'd drill and tap a hole in the bottom to screw in a drain valve. Or, if it's too thin, drill it and TIG a nut to the bottom to screw in a drain valve. Trim the threads of the valve to not protrude higher than the floor of the reservoir so it drains fully.

it's definitely thick enough to put a drain in. I might do that.

I'll see how much it gets. I also have a oil sucker, I could suck it out the dip stick whole while doing oil.

I probably should have researched catch cans lol. it was a cheap. Amazon impulse buy haha. so it is what it, at this point parts are stacking up for this thing. I need to actually work on it.

 

[j91z28d1]

I'm not 100% sure, but I think the alt's output regulation is controlled by a PWM signal from the PCM. It's not an "on/off" signal. It may not be PWM, it could be a reference voltage scale. Whatever it is, GM, apparently, kept the same control design on the succeeding generations. Looks like I have researching to do.

as I understand it there's an entire programming for voltage and battery maintenance in your trucks. lot of it isn't defined in hp. some ways I like that hp doesn't define things that aren't needed by everyone so to not over complicat tuning, other ways if you go down the ribbit hole far enough you realize how much they left out of how the routines run. gm used a bunch of math to calculate the battery temp and health. so yeah, the ecm is doing its thing and saying OK at this point the battery voltage should be this, and that's anywhere from 14v to 10.8v, I think I've read and then using the pwm output to the alt it will vary the signal to run that voltage it's requesting at that time. I believe you can change some of the numbers but I don't believe we can really make best use of the agm batteries. that would need an battery engineer level of understanding what the agm battery needs to last the longest and how to correctly maintain it. it definitely can be done, but I don't think with the level of access hp provides.

it has been done by gm thou, some cars use agm factory and they have done the programing for that battery. I have one with a agm and I just replaced it at 8 years and 95k miles. it still load tested pretty good, I replaced it more on age and load test. I ended up swapping it into another car I have and it's doing well still, probably spent that money for nothing.
what we'd need is full access to change all the parameters to what they used in the agm cars. or maybe even a segment swap like you can do when miss matching auto tranny swaps if the batterys at so different they wrote a whole new sub routine.

yeah.. to much.

 

[j91z28d1]

I do have HPT. So that's all the difference is- preferred charging voltage? What about the RVC stuff?

the voltage that each battery is considered 100% charged is different. but not a lot thou. plus the internal resistance is less for an agm so it will accept charge much faster after crank. how that effects real world swaps, I don't know. but engineers need to take that into consideration. plus battery Temps they like different voltages as well.

here's a few charts I found to compare. gives an idea of what I've read. charging agm to voltage that leaves flooded at 100% might leave your agm under charged. but they do tend to handle under better than over. so there's that.




I read a few days when trying to decide to switch this hybrid yukon to agm or leave it flooded. in the end I said eh, give me the agm. rock auto will ship those and not flooded haha.

 

[89Suburban]

Last Thursday, the kiddo and I went to hang with the Texas fam at a beach house VRBO in Galveston. Terramar Beach, to be specific. Spent Friday and Saturday on the beach and drove home Sunday.

View attachment 402401


That bird's lookin back like "to shit or not to shit?"

View attachment 402402



Last night, I took McKinley to a concert in New Orleans. This is the second year in a row that she's requested to see live music for her bday present. I couldn't say 'no' to that! Her bday is over a month from now, but she wanted to see Pixies. Franz Ferdinand and Bully opened for them. I've never heard of Bully and had forgotten how cool Fran Ferdinand is. They had great energy and put on a good show. Oh- what I did to my GMT900... I parked it as safe as possible in a paid parking garage:

View attachment 402403

Pretty confident on that sand or was your ass puckering at all?

 

[mikez71]

I set my voltages to be between 13.8 - 15 V.. Not sure if it helps, but it sounds like AGM's need higher voltages typically, yet don't tolerate overcharging as well as flooded..
Still see 13.6V on cig port, but I notice with the fan on, it will drop .2V or so, and turning it off, the cig voltage will climb back up after a few seconds.

Also have thought about disabling the RVC as AGM's are supposed to work moderately well in older vehicles. I'm guessing the charging logic undercharges the AGM if anything. Might think the battery is at a higher state of charge and not charge it 100%. My typical key on battery voltages are around 12.5V.. have seen it as low as 12.3..
Looking at the chart j91z posted, that doesn't seem too bad (70-80% charge)


I bypassed my heater core last night, still smelled coolant this morning. Thinking it might be the coolant left in heater core..
What's the best way to evacuate it? Seems like I might have to hook up a pump and pump water through it?

 

[j91z28d1]

I set my voltages to be between 13.8 - 15 V.. Not sure if it helps, but it sounds like AGM's need higher voltages typically, yet don't tolerate overcharging as well as flooded..
Still see 13.6V on cig port, but I notice with the fan on, it will drop .2V or so, and turning it off, the cig voltage will climb back up after a few seconds.

Also have thought about disabling the RVC as AGM's are supposed to work moderately well in older vehicles. I'm guessing the charging logic undercharges the AGM if anything. Might think the battery is at a higher state of charge and not charge it 100%. My typical key on battery voltages are around 12.5V.. have seen it as low as 12.3..
Looking at the chart j91z posted, that doesn't seem too bad (70-80% charge)


I bypassed my heater core last night, still smelled coolant this morning. Thinking it might be the coolant left in heater core..
What's the best way to evacuate it? Seems like I might have to hook up a pump and pump water through it?

2 rubber caps on the core to block the smell? flushing it out with a water hose would work but then you get it everywhere and you might smell it from there?

on battery v, yeah I've found the voltage at the battery posts themselves with a good meter can be a bit different than what the bcm says. plus most charts that tell you what % charged are from voltage is unloaded resting batteries. so as soon as you connect anything that goes out the window.

I researched myself in a circle and then said eh, and just bought one.

 

[Doubeleive]

I set my voltages to be between 13.8 - 15 V.. Not sure if it helps, but it sounds like AGM's need higher voltages typically, yet don't tolerate overcharging as well as flooded..
Still see 13.6V on cig port, but I notice with the fan on, it will drop .2V or so, and turning it off, the cig voltage will climb back up after a few seconds.

Also have thought about disabling the RVC as AGM's are supposed to work moderately well in older vehicles. I'm guessing the charging logic undercharges the AGM if anything. Might think the battery is at a higher state of charge and not charge it 100%. My typical key on battery voltages are around 12.5V.. have seen it as low as 12.3..
Looking at the chart j91z posted, that doesn't seem too bad (70-80% charge)


I bypassed my heater core last night, still smelled coolant this morning. Thinking it might be the coolant left in heater core..
What's the best way to evacuate it? Seems like I might have to hook up a pump and pump water through it?

water hose on one side will work fine, heater core does not hold much fluid very easy to flush it out.
I have been monitoring my voltage with a led on the cigarette port I have yet to see it drop below 14v usually stays 14.2-14.4, startup occasionally makes 16v usually about 15.4-15.6 that's with a 260amp mechman standard pulley.