What did you do to your NBS GMT800 Tahoe/Yukon Today?

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

Logan5

Member
Joined
Jul 6, 2021
Posts
95
Reaction score
308
Location
Albany, NY
Evap code is back. Recently did the vent & purge valves so today was playing detective to find the leak. Pulled the vent valve hose and stuck a cork in there to seal it up. Pulled the purge valve hose and blew air in. Can feel the leak. Hooked up a low pressure feed from air compressor to the purge valve hose and started listening for a hiss. The hiss and some clicks definitely coming from the top of the gas tank. SOB. Guess I have to drop the tank now. Just filled it up yesterday.
 

Tonyrodz

Resident Resident
Joined
Feb 16, 2012
Posts
31,015
Reaction score
45,204
Location
Central Jersey
Or, less likely, the engine coolant temp sensor is mis-reporting to the PCM.

Even if the stat was stuck open, wouldn't the entire system reach normal operating temp at some point? Unless it was like 0 degrees (or below) outside, wouldn't it get there eventually after running for a while (even with a stat stuck open)?
While unlikely, as you say, I would still be willing to think the sensor sending suspect data to the ECM is still possible.
The heat comes out ok from the vents. What's a good way to tell which one is the issue? Thermostat or the temp sensor?
 

Scottydoggs

Full Access Member
Joined
Dec 16, 2017
Posts
2,523
Reaction score
3,674
Location
NJ
The heat comes out ok from the vents. What's a good way to tell which one is the issue? Thermostat or the temp sensor?
touch both heater core hoses. if they are hot hot like normal the sensor died, its a two part sensor, one 1/2 sends info to the pcm, the other to the cluster. if cold/luke warm the t stat is likely open.
 

MassHoe04

Full Access Member
Joined
Nov 4, 2021
Posts
1,586
Reaction score
2,798
Location
Western MA
The heat comes out ok from the vents. What's a good way to tell which one is the issue? Thermostat or the temp sensor?
You are going to be well above freezing today in NJ. Like 50+... I can't see how the system could be at 160-165 with a stat stuck closed or open.

If you still read that low, I would be shocked to hear it was a bad stat and not the sensor (or wiring/connectors). Maybe it is not always a high probability in a lot of reported issues, I think @Fless original hunch might be onto something. Keep us posted.
 

Walchit

Full Access Member
Joined
Aug 29, 2021
Posts
447
Reaction score
911
Machine shop called. Heads pressure tested good, cam bearing hole isn't wallered out, and magnaflux showed zero cracks. Now to decide if I should just slap these pistons in or go to flat top, or 5.7. I'm gonna ask for some prices when I pick the block up, that should push me towards re-using the stock ones, lol
That premium gas price has me re-thinking the higher compression ratio for sure.
 

TEXCHEVY

Full Access Member
Joined
Jan 14, 2018
Posts
123
Reaction score
299
Location
Italy
How bout this one?
I mounted the sensors, spartan work!!! :)) (the kit has not yet arrived), I traveled about 100 km, at the moment no error code in diagnosis. Engine light off. The engine runs well on gasoline and also lpg
 

Attachments

  • IMG_7816.jpeg
    IMG_7816.jpeg
    308.4 KB · Views: 9
  • IMG_7818.jpeg
    IMG_7818.jpeg
    334.1 KB · Views: 9

Forum statistics

Threads
129,333
Posts
1,814,139
Members
92,470
Latest member
juniordaboi909

Latest posts

Top