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

[gooffeyguy]

A note on charging voltages, doesn't turning tow/haul mode on disable the EPM system?

 

[RooTBeeRthe1st]

A note on charging voltages, doesn't turning tow/haul mode on disable the EPM system?

Oh interesting, I never use it. I might have to play with that on the way to work tomorrow morning and see if it makes a difference.

 

[RooTBeeRthe1st]

Next up: that Cold Case radiator I installed in the 2012 three years ago appears to be leaking but I can't figure out from where. I stupidly used worm drive hose clamps on the upper and lower radiator hoses and the one on the lower hose at the radiator keeps requiring tightening. And there is coolant puddling on the crossmember right beneath it. But yesterday it was snug and I still lost a pint of coolant with fresh puddling going on so it's clearly leaking from somewhere else as well. It's losing enough that it requires topping off before every trip - most of which are towing.

So I said f-it and ordered a new Denso radiator from Rock Auto with the 1-1/4" core along with the K5L fans and shroud because I had to modify the original to accommodate the Cold Case. These plus some other odds and ends and I ended up with a $600 bill with shipping because they came from 3 different warehouses. Se la vie. It's only money and I keep a savings account for car stuff.

It's annoying the pricey aluminum radiators for these appear to be a scam. To my knowledge at least half a dozen guys here who bought them had leaks within 2 years. I thought I had been lucky and escaped the poor quality, but it appears not.

I'm pretty sure my Cold Case has been leaking for maybe a good 6 months at this point. Also not sure exactly where yet. I think it's somewhere right in the center and down low potentially. I need to pull the bumper one of these days and find it before summer kicks off.

Only reason I've been able to put it off so long was because it was hot and suck down coolant and I topped it off, let it idle for a long time in place after working on something else and realize there was a small puddle of coolant under it, and then have just monitored the coolant since to make sure it's not low.

But for the most part through winter, I never got the coolant hot enough to where it built enough pressure to leak out, but once it starts warming up here, sitting in traffic, it's going to be doing that a lot.

I'm not ready to give up on this one, I'm either going to get some aluminum brazing rods and if I can find the leak plug that junk myself, or if it's really bad, head over to the local welder and have him fix it.

 

[Grady_Wilson]

They really need to be flexible to get them in and out. Not sure if they make a material like that that can be 3D printed?

I own a 35 year old motorcycle and there was one guy that 3D printed some gas tank rubber mounts.
I bought a set and they were very pliable and rubber like.
No idea what material they are but they are very rubber like.

 

[Geotrash]

I'm pretty sure my Cold Case has been leaking for maybe a good 6 months at this point. Also not sure exactly where yet. I think it's somewhere right in the center and down low potentially. I need to pull the bumper one of these days and find it before summer kicks off.

Only reason I've been able to put it off so long was because it was hot and suck down coolant and I topped it off, let it idle for a long time in place after working on something else and realize there was a small puddle of coolant under it, and then have just monitored the coolant since to make sure it's not low.

But for the most part through winter, I never got the coolant hot enough to where it built enough pressure to leak out, but once it starts warming up here, sitting in traffic, it's going to be doing that a lot.

I'm not ready to give up on this one, I'm either going to get some aluminum brazing rods and if I can find the leak plug that junk myself, or if it's really bad, head over to the local welder and have him fix it.

I'll be interested to hear what you find. I'll share details of where mine is leaking once I get to working on it in a couple of weeks. If it's a mechanical failure such as due to rubbing, then I may have it repaired to keep as a spare. I'm using the rig with the Cold Case to tow our camper this weekend, so fingers crossed! I'll have a couple of gallons of coolant in the back, ready to go.

The new radiator has been here for a couple of days but I'm still waiting on the fans and shroud or I would've had it done by now.

 

[RooTBeeRthe1st]

I'll be interested to hear what you find. I'll share details of where mine is leaking once I get to working on it in a couple of weeks. If it's a mechanical failure such as due to rubbing, then I may have it repaired to keep as a spare. I'm using the rig with the Cold Case to tow our camper this weekend, so fingers crossed! I'll have a couple of gallons of coolant in the back, ready to go.

The new radiator has been here for a couple of days but I'm still waiting on the fans and shroud or I would've had it done by now.

Yeah I've had a couple gallons of coolant and distilled water in the back for months because I knew about it and I've been planning to figure out what's going on. Haven't had a chance it's been raining every weekend here just about.
It actually was so long that the two and a half gallon jug of distilled water decided to spring a leak and start jumping all over the back which was a fun problem thankfully I caught it after only maybe a half gallon had leaked out.

I wonder if the guys with the newer style Cold Case are going to have issues as well

 

[RooTBeeRthe1st]

I own a 35 year old motorcycle and there was one guy that 3D printed some gas tank rubber mounts.
I bought a set and they were very pliable and rubber like.
No idea what material they are but they are very rubber like.

TPU is a commonly used soft and malleable filament

 

[Sparksalot]

Yeah I've had a couple gallons of coolant and distilled water in the back for months because I knew about it and I've been planning to figure out what's going on. Haven't had a chance it's been raining every weekend here just about.
It actually was so long that the two and a half gallon jug of distilled water decided to spring a leak and start jumping all over the back which was a fun problem thankfully I caught it after only maybe a half gallon had leaked out.

I wonder if the guys with the newer style Cold Case are going to have issues as well

I haven’t noticed anything yet, but I’ve only driven it about 5,000 miles since I installed the radiator 2 years ago.

 

[Doubeleive]

Yeah I've had a couple gallons of coolant and distilled water in the back for months because I knew about it and I've been planning to figure out what's going on. Haven't had a chance it's been raining every weekend here just about.
It actually was so long that the two and a half gallon jug of distilled water decided to spring a leak and start jumping all over the back which was a fun problem thankfully I caught it after only maybe a half gallon had leaked out.

I wonder if the guys with the newer style Cold Case are going to have issues as well

mine lasted about 3 months and started leaking at the seam between the fin's and end cap, upper left inside edge, behind the fan shroud
it was getting dried out before hitting the ground, knew it was leaking but was hard to find until I pulled the fans out and saw the orange/redish tint on the aluminum.

 

[j91z28d1]

I wonder if these aluminum radiators are the ones I've only heard rumors about that aren't welded tube to end tank but epoxy together.

 

[mikez71]

A note on charging voltages, doesn't turning tow/haul mode on disable the EPM system?

Oddly enough, mine doesn't seem to bump the voltage in tow/haul mode. Possibly because I changed some settings.
Supposed to happen with headlights on as well but I don't notice it. I usually hit 14.8V after startup, then drop to 13.7V after awhile..

something about 'idle boost' in the wiring diagrams. Haven't every heard of anyone experiencing an idle bump.

 

[Doubeleive]

Oddly enough, mine doesn't seem to bump the voltage in tow/haul mode. Possibly because I changed some settings.
Supposed to happen with headlights on as well but I don't notice it. I usually hit 14.8V after startup, then drop to 13.7V after awhile..

something about 'idle boost' in the wiring diagrams. Haven't every heard of anyone experiencing an idle bump.

View attachment 424958

that looks like cold weather induced, I have experienced 2nd level many times but don't recall ever having a 3rd level happen, unless it was right at startup for a few seconds

 

[Fast_AT4]

Deez things.



View attachment 424923View attachment 424924

If anyone has a PN for this, I'd be curious what it look like under and the size. I'd assume the Left and Right is the same, just mirrored.

 

[Doubeleive]

If anyone has a PN for this, I'd be curious what it look like under and the size. I'd assume the Left and Right is the same, just mirrored.

no they are different, one side is wider than the other, silverado/sierra's have them as well also different....
on the bottom both sides use common metal retention clips used by gm

 

[Fless]

If anyone has a PN for this, I'd be curious what it look like under and the size. I'd assume the Left and Right is the same, just mirrored.

For a 2008 Tahoe: (https://www.gmpartsdirect.com/v-2008-chevrolet-tahoe--ls--5-3l-v8-gas/body--cowl)

 

[j91z28d1]

Oddly enough, mine doesn't seem to bump the voltage in tow/haul mode. Possibly because I changed some settings.
Supposed to happen with headlights on as well but I don't notice it. I usually hit 14.8V after startup, then drop to 13.7V after awhile..

something about 'idle boost' in the wiring diagrams. Haven't every heard of anyone experiencing an idle bump.

View attachment 424958

as I understand idle boost from the hpt research I did a while back, it's the ecm being able to raise the idle of the alt can't keep up with the amp load, it can request a higher idle to keep up. the example given was a rainy hot day, full ac running, lights, wipers and all sitting in traffic for long time.

my c6 e38 has it defined in and populated in hpt, but it's not enabled size) since it was a old school 4 pin with a fuse box ref wire, I had hoped enabling it would give me a pwm out out to control the truck one. Sadly it isn't complete, if I command L term in when switched to pwm I would put a pwm out, but not control it and wouldn't turn on without manually doing it. i asked them if a segment swap was possible to add it, but it fell on deaf ears. to old to support to that level.

14.7v for a while after start and then switch down to 13.8 sounds the most correct I've heard for a agm. you might have cracked it.

 

[kbuskill]

My first Cold Case Radiator (original design) lasted 2 years/30,000 miles.

Replaced under warranty with 2nd design in 2022, no issues as of yet.

Mine was leaking into the tray under the Radiator as well and appeared to possibly have some cracking around the mounting posts on the bottom and maybe where the tubes met the tank at the bottom, but couldn't verify exactly.

 

[solli5pack]

My first Cold Case Radiator (original design) lasted 2 years/30,000 miles.

Replaced under warranty with 2nd design in 2022, no issues as of yet.

Mine was leaking into the tray under the Radiator as well and appeared to possibly have some cracking around the mounting posts on the bottom and maybe where the tubes met the tank at the bottom, but couldn't verify exactly.

View attachment 425020View attachment 425022View attachment 425023

Is that a petcock valve I see on there for draining the coolant?! Why didn't GM do this?

 

[gooffeyguy]

The same reason GM made it a PITA to change a headlight bulb

 

[solli5pack]

The same reason GM made it a PITA to change a headlight bulb

Tell me about it! My d/s daytime running light has been out for 3 weeks and for whatever reason I can't bring myself to set aside the 10 minutes to pull thr liner and replace it. I'd rather pull a cylinder head....