2007 Yukon..Common places to check for coolant leak.

[petethepug]

The plastic on the radiator tanks likes to stress crack. After the hot coolant stops circulating in the system from the engine off you can follow the trail. Another method is to turn the a/c on full blast and as many electrical accessories as possible and the pressure / temp increase from the load on a hot day will reveal the source of the leak. On our 08 Denali it was two cracked radiator side tanks and a crack in the coolant overflow.

 

[2007 Denali XL]

get a flashlight and get under the truck.
check bottom of the radiator
check under the water pump
check hoses that connect to water pump including the plastic T to the reservoir tank/heater
check the reservoir tank
check the 2 heater hoses that go into the firewall (passenger side) those also both have a T (these are very typical to break or crack over time)
check down both left & right side of radiator from the top
if you still can't find the leak, then leave a large piece of cardboard under the suspect area overnight and look at it in the morning (before you start or move the vehicle), look at the wet spot and directly above it will likely be your source.
you will not have any coolant leak on the driver side unless it is the radiator at the front.

thanks, these are very helpful ideas. Changed the Firewall hoses 2 years back, hopefully they have not gone again

 

[2007 Denali XL]

Looks like it's the heater hose, leaking under the Y connector near the engine block. Got a Dorman replacement with a steel Y connector, hopefully this should be pretty durable.

 

[992dr]

I've always said passenger side or drivers side

I'm going to guess its the passenger side and it sounds like it may be this
https://www.partsgeek.com/gbproducts/AC/18976-05658167.html?utm_source=google&utm_medium=ff&utm_content=NC&utm_campaign=PartsGeek+Google+Base&utm_term=2007-2014+Chevrolet+Suburban+1500+Heater+Hose+Set+Dorman+626-553+Outlet+07-14+Chevrolet+Heater+Hose+Set+2011+2008&fp=pp&gbm=a&utm_source=google&utm_medium=ff&utm_campaign=PartsGeek+Google+Basecid=6774379819&aid=79287199093&keyword=833350606290:la-833350606290&kid=833350606290&gclid=EAIaIQobChMIh8_V-Pu87AIVEG-GCh0IKAUpEAQYAyABEgJmDPD_BwE

This

Recently replaced mine

 

[DBacon]

My 2007 leaked along the rear heater lines, aluminum tubes tightly clamped every couple feet to the rocker panel. Leaked at a couple clamped areas. Rather than redesign that method of mounting the hoses, I just capped them off. BTW the AC tubing was already capped off... Many stories on the web about these leaking, I think they should have considered the expansion of the lines when mounting them, you can't fight it!