Coolant Leak 2015 Sierra

SkiDooNick700 · August 4, 2021

Hey guys, 2015 GMC Sierra 6.2 NHT April 2015 build.

All of a sudden I've got a coolant leak but haven't been able to pinpoint where from. I see the drivers side frame wet and will drip to the ground. Coolant level already down up to 2 inches from Cold line. It's even wet on the back side of the lower valence. Just noticed this leak after a 200-300 mile trip back from vacation.

Dried up the frame, took it on a 3 mile drive, already dripping with coolant.

Any advice? I am not sure where else to look - might need to start pulling stuff off the truck to get a better view?

Is my truck build date part of the known TSB? Is it possible to see the stress cracks per the TSB without disassembling anything?

Snowcamo · August 5, 2021

Bottom of the water pump usually has a weep hole. Try there. That's not to bad of a job if your mech inclined.

CamGTP · August 5, 2021

$5 it's the radiator that needs to be replaced.

SkiDooNick700 · August 5, 2021

55 minutes ago, Snowcamo said:

Bottom of the water pump usually has a weep hole. Try there. That's not to bad of a job if your mech inclined.

I will have to take a look to see if it is wet. It didn't cross my mind to check it.

50 minutes ago, CamGTP said:

$5 it's the radiator that needs to be replaced.

I am worried this may be the case lol. There is like a tray or something running under the radiator and it is wet all along it from what I am able to see visually.

CrawlSlow · August 5, 2021

I would start with the easy stuff first before taking things apart.. Drain plug, check along side of radiator to see if it's wet.

SkiDooNick700 · August 5, 2021

10 hours ago, CrawlSlow said:

I would start with the easy stuff first before taking things apart.. Drain plug, check along side of radiator to see if it's wet.

Thanks for the tips. Is the drain on the passenger side?

As far a checking the sides of the radiator, I swear I've looked at every possible angle top and bottom left and right and I am not able to get a clear visual of the sides of radiator.

I watched a video it seems like a pretty quick process to remove the top cover piece, air box, and fans. Thinking this might help my view out.

Edited August 5, 2021 by SkiDooNick700

CrawlSlow · August 5, 2021

On passenger side just behind the bottom radiator hose, you can't see it but you can feel it.

SkiDooNick700 · August 5, 2021

Well guys looks wet at drivers side corner of radiator. I'm thinking it is cracked somewhere? Going to try to pressure test.

It was pretty easy to get the fans out the way, just took me a while to figure out the clips and such. I need to buy the right tool for the job lol.

SkiDooNick700 · August 6, 2021

On 8/4/2021 at 8:06 PM, CamGTP said:

$5 it's the radiator that needs to be replaced.

You appear to be the winner! Took some things apart including removing fan shroud. Did a pressure test, the drivers side corner of radiator is leaking. It was a pool in no time.

Now to find a new one, looks like GM replaced with a new part number.

Gagliano7 · August 6, 2021

https://www.rockauto.com/en/catalog/chevrolet,2015,silverado+1500,5.3l+v8,3307665,cooling+system,radiator,2172

SkiDooNick700 · August 6, 2021

4 hours ago, Gagliano7 said:

https://www.rockauto.com/en/catalog/chevrolet,2015,silverado+1500,5.3l+v8,3307665,cooling+system,radiator,2172

Thanks yep I used RockAuto to figure out the updated number. Called a local "dealer" who has one in stock, about 350$. Had to purchase via their website to get that price otherwise they have to sell for 500+ in person. Something about GM e-commerce policy.

Ravenkeeper · August 12, 2021

On 8/4/2021 at 5:00 PM, Snowcamo said:

Bottom of the water pump usually has a weep hole. Try there. That's not to bad of a job if your mech inclined.

Usually when the water pump plug goes, it's a huge mess, and not driveable. It will blow out all of your coolant.

On 8/6/2021 at 6:39 AM, SkiDooNick700 said:

Thanks yep I used RockAuto to figure out the updated number. Called a local "dealer" who has one in stock, about 350$. Had to purchase via their website to get that price otherwise they have to sell for 500+ in person. Something about GM e-commerce policy.

Cheaper than RA?

SkiDooNick700 · August 12, 2021

7 hours ago, Ravenkeeper said:

Usually when the water pump plug goes, it's a huge mess, and not driveable. It will blow out all of your coolant.

Cheaper than RA?

Rock Auto has it for 335 plus $20 shipped. It was more or less a wash. At that point I said to myself let me get locally if I can instead of having a radiator potentially tossed around by UPS or FedEx.

Finished install of new one last night, took on 20 minute test drive. All seems good so far. I need to do a good washing of the engine bay now, there is so much coolant still down the frame and such lol.

I think I am going to order a new T Stat, my temp gage always fluctuated a tad but very very recently (last 100 miles) it's doing some big swings, from 210 down a line and back up to almost 210.

Also my idle seemed kinda rough yesterday not sure what is up with that. She's going through a phase!

diyer2 · August 12, 2021

instead of having a radiator potentially tossed around by UPS or FedEx.

They delivered the part you bought I bet.

elcamino · August 12, 2021

There was a service bulletin on leaks, had my 2015 repaired under warranty for leaks. In short faulty thermostat cause radiator failure.

Quote

This condition may be the result of excessive thermocycles within the cooling system caused by excessive cycling of the thermostat. These excessive thermocycles within the coolant system may cause the tubes to fatigue, crack and leak at the radiator headers. To correct this condition, a new thermostat has been designed that eliminates the
thermostats excessive cycling. If this condition is found, in addition to replacing the radiator, the engine coolant thermostat housing (w/thermostat) must also be replaced. Refer to Engine Coolant Thermostat Housing Replacement in SI, which is located in the Engine Heating and Cooling section.

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&ved=2ahUKEwiA-7iSyqvyAhUIVc0KHd6zACMQFnoECAYQAQ&url=https%3A%2F%2Fstatic.nhtsa.gov%2Fodi%2Ftsbs%2F2019%2FMC-10155058-9999.pdf&usg=AOvVaw2ifEl9-OC04g37-bj7JXC2

Edited August 12, 2021 by elcamino