2017 Cadillac ATS 2.0T - Coolant Issue Triage

[webfors]

Had to add a litre of coolant to the reservoir this week. My wife was reporting no heat on her commute to work so I went through the typical culprits and found no coolant in the reservoir. Purchased some Dexcool, mixed at 55/45, and filled up the reservoir. Heat started working perfectly again.

Now to make a list of potential root causes that I can get the dealer to investigate (I'm still under powertrain warranty for another 1k miles).

• Coolant hoses
• Radiator
• Engine gaskets
• Thermostat

Any others to add to the list from BITOG collective wisdom? I'm thinking a UOA is in order to ensure no coolant in oil.

Car is going in Thursday for new sway bars, tranny drain and fill, rear diff drain and fill, and of course troubleshooting the coolant loss. I did find one return hose that was bubbling/leaking at the Y joint. If that's the root cause, that's an easy fix.

 

[TomYoung]

You probably have your answer. Do you know how long it took to lose that liter of coolant?

 

[ARCOgraphite]

WP seals is another place. My Wife's toyota used to leak there on brutally cold mornings.

Looks like you found it with that leaky WYE

 

[webfors]

You probably have your answer. Do you know how long it took to lose that liter of coolant?

I'm a bit ashamed, as a BITOG'er, that I don't know. I suspect it was a long'ish affair if the only leak is that return hose. The HVAC/Heating issue only started the last week, but it could have been leaking for quite a while.

 

[webfors]

WP seals is another place. My Wife's toyota used to leak there on brutally cold mornings.

Looks like you found it with that leaky WYE

Acronyms! Can you expand on WP and WYE for me?

 

[grisby]

WP= water pump, WYE= correct plumbing term for Y connector/branch

 

[IndyIan]

South main auto on youtube did an episode on an ATS with coolant loss and I believe it was the wye cracked and a leaking radiator on a 2.5L ATS. The rad is hard to inspect IRCC.

 

[webfors]

WP= water pump, WYE= correct plumbing term for Y connector/branch

Water Pump & seals added to my list! Thank you.

 

[webfors]

Dealer just called and it's the WYE hose on initial inspection. They are going to replace the hose, replace the coolant, perform a pressurization test, and report back.

 

[webfors]

I was concerned about the radiator, after reading a few 13/14 model year ATS have rotted radiators after a few years. However, they ran a cam to the typical radiator problem spots and it looks clean.

 

[webfors]

Got the car back, runs perfect again. Keep an eye on those WYE hose folks! Looks like mine has been leaking for a while and I should have caught it earlier.