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

[gooffeyguy]

Doing a block check test can help narrow it down too. It detects combustion products in the coolant.

https://www.amazon.com/Block-Tester-BT-500-Combustion-Leak/dp/B06VVBSFTF

Good idea!

Lol

 

[mikez71]

Doing a block check test can help narrow it down too. It detects combustion products in the coolant.

Yeah, but at this point with coolant in the exhaust, what else could it be but head/headgasket? (crack in cylinder?)

but either way the tester won't tell me where, I figure head must come off..

 

[Doubeleive]

Yeah, but at this point with coolant in the exhaust, what else could it be but head/headgasket? (crack in cylinder?)

but either way the tester won't tell me where, I figure head must come off..

for a $20 bet I would use the tester to see what it shows or does not show, you already thought it was the heater core....
I bet it is something under the hood be it head or not when you start it up whatever smell is under the hood gets pushed out the hood right into the nostrils
my hardest one was a literal pin hole leak in a radiator hose it only leaked when you shut the vehicle off for a second and that was it, little piss out and done not even enough to leave a drop on the ground. I think I only found it by accident.

 

[Sparksalot]

Yeah, but at this point with coolant in the exhaust, what else could it be but head/headgasket? (crack in cylinder?)

but either way the tester won't tell me where, I figure head must come off..

But it would tell you definitively if there is a leak into the coolant. Better to eliminate the easy stuff before tearing the engine open.

 

[mikez71]

for a $20 bet I would use the tester to see what it shows or does not show, you already thought it was the heater core....
I bet it is something under the hood be it head or not when you start it up whatever smell is under the hood gets pushed out the hood right into the nostrils

Very true! I hope you're right! (With my luck it will be head and heater core..)

Waiting for the expansion tank and a couple hoses first so I can try pressurizing again.
I would think with a pinhole that I could still pressurize it somewhat. (Or a small HG leak for that matter)

If no change, I will do the combustion gas check.. certainly don't want to pull the head for no reason.

 

[j91z28d1]

I've never had one that wouldn't build even a little pressure. even ones that spray coolent out of a hose. something isn't correct. not sure what, but it's a pretty large leak and above the water line. so that pretty much means how pump attachment itself.

 

[mikez71]

I've never had one that wouldn't build even a little pressure. even ones that spray coolent out of a hose. something isn't correct. not sure what, but it's a pretty large leak and above the water line. so that pretty much means how pump attachment itself.

Havent done it before, but totally agree!

I'm hoping its the tank seam and will try another tester shortly.

 

[j91z28d1]

Havent done it before, but totally agree!

I'm hoping its the tank seam and will try another tester shortly.

I don't mean to it to sound dumb but did you block off the over flow hose?

 

[mikez71]

I don't mean to it to sound dumb but did you block off the over flow hose?

View attachment 402694

I do have a smaller hose from radiator that connects to the tank above coolant level. Did order a new hose as well. Shouldn't have to plug it as it goes to the radiator I hope? I was going to disconnect it but couldnt find the right size plug and gave up.

 

[Doubeleive]

I don't mean to it to sound dumb but did you block off the over flow hose?

View attachment 402694

pretty sure the pressure tester fitting covers the overflow hole, it did on the wife 04 and there is little difference on the gmt800's

 

[iamdub]

You know I was watching for it to sensor that one. But the net nanny lets that nip slip.

 

[j91z28d1]

I do have a smaller hose from radiator that connects to the tank above coolant level. Did order a new hose as well. Shouldn't have to plug it as it goes to the radiator I hope? I was going to disconnect it but couldnt find the right size plug and gave up.

I guess yours is different than mine. wonder where the overflow is?

 

[j91z28d1]

pretty sure the pressure tester fitting covers the overflow hole, it did on the wife 04 and there is little difference on the gmt800's

looking at the screw on part, the seal is at the very top, how mine is setup. I don't thing it would seal it off. the old school kinda that just pushed down and locked with a half turn it did.

but guess mine is pretty different.

 

[89Suburban]

You know I was watching for it to sensor that one. But the net nanny lets that nip slip.

There's many a slip 'twixt the cup and the lip

Name that movie

 

[mikez71]

I guess yours is different than mine. wonder where the overflow is?

I assumed it would just leak out from under the cap? idk

 

[j91z28d1]

I assumed it would just leak out from under the cap? idk

yeah, guess so. wouldn't have expected that. everyone I have has a 2nd hose for a to drain any over flow down and away.

huh. gm.. what can ya do

 

[iamdub]

There's many a slip 'twixt the cup and the lip

Name that movie

I'd be the last to know. Not a movie buff. Hell, I couldn't even tell you where my TV remotes are at the moment. I know where my stereo remote control is, though! (It's on my phone- Yamaha AV Controller app)

 

[iamdub]

yeah, guess so. wouldn't have expected that. everyone I have has a 2nd hose for a to drain any over flow down and away.

huh. gm.. what can ya do

It's a sealed and pressurized system. There is no "overflow" like the older generations. That which looks like an overflow tank with a pressure-rated "radiator cap" on it is a surge tank. That nipple by the cap is to expel what would get by that cap in an over-expansion or over-pressurization event. If coolant is leaking out of that, then the "rad cap" is leaking and the surge tank is too full.

 

[j91z28d1]

It's a sealed and pressurized system. There is no "overflow" like the older generations. That which looks like an overflow tank with a pressure-rated "radiator cap" on it is a surge tank. That nipple by the cap is to expel what would get by that cap in an over-expansion or over-pressurization event. If coolant is leaking out of that, then the "rad cap" is leaking and the surge tank is too full.

I get that.. but all 3 of my newer gm cars have it. the yukon and volt have 2, one on both cooling systems.

when I threw a belt at the track on the c6 it emptyed it radiator thru that hose onto the ground. just seems weird for some to have it and others not.

 

[avalonandl]

Tried replacing the running board motors on Deathscalade but no dice! motors are corroded to the bracket so returning the running board motors and reordering the motors with new brackets which are $$$ I guess this is the perk to driving older stuff but I was hoping I could replace just the motors and not the motor + bracket since the price increase is substantial


/rant

I gave up on the folding running boards and just went with stationary tube boards