Mystery Losing Coolant

[murphyblack]

I am losing about a quart of coolant from my 2009 Chevy Tahoe every few weeks. I have 251,000 miles but the engine and mechanicals have been well maintained and in good shape. Changed the water pump and all hoses last year and recently replaced the overflow reservoir on the advice from this forum to no avail. My oil and trans fluids are clear so no sign of coolant leaking into these. I have no visible leaks on the driveway or garage. I just cannot understand where the coolant is going?? I have about given up and was going to pour in a bottle of Bar engine block sealant but really dont want to do so unless totally necessary.
Does anyone have any other suggestions of where to look??

I found the T-valves for heater up against the Firewall just a touch past the middle of the firewall on passenger side to leak just enuff to allow my Coolant level to drop and the liquid evaporated. Never any liquid on the ground so remained a mystery for a number of years. Mine was so slow, I just carried coolant, checked it regularly and added regularly as needed. It took a while to figure it out. It might be beneficial to wrap a couple of paper towels around those T's with a twist tie so you can see the moisture after they get hot and build up pressure. If you replace one, just do them both. I found another list on this website noting other locations notorious for leaking coolant. Best to you it is frustrating.

 

[Bobio2003]

Next time you shut it off while hot at night, look under the hood and under the vehicle with a flashlight. It helps me find leaks because of the steam.

 

[OR VietVet]

Next time you shut it off while hot at night, look under the hood and under the vehicle with a flashlight. It helps me find leaks because of the steam.

@Bobio2003, you can quote and respond in same post.

 

[steve welling]

check heads on 5.3 i have 3 suburbans and 1 yukon xl that the aluminum heads have cracked on. a gm problem.

 

[murphyblack]

I am losing about a quart of coolant from my 2009 Chevy Tahoe every few weeks. I have 251,000 miles but the engine and mechanicals have been well maintained and in good shape. Changed the water pump and all hoses last year and recently replaced the overflow reservoir on the advice from this forum to no avail. My oil and trans fluids are clear so no sign of coolant leaking into these. I have no visible leaks on the driveway or garage. I just cannot understand where the coolant is going?? I have about given up and was going to pour in a bottle of Bar engine block sealant but really dont want to do so unless totally necessary.
Does anyone have any other suggestions of where to look??

I had similar issue with 03 Tahoe. I wrapped a white paper towel around both T connections going in to firewall and tied them on. There was a small leak from both that evaporated and never showed from looking on either side or from the grill, but the coolant showed up on the paper towel. If it is leaking in the summer it will get hot enuff after getting it up to temp and driving a bit further to verify if this is the location of your leak. I have found this method of locating them better than the smell test or looking for residue around the leak. I fought the leaks on the firewall Ts for months, there was nothing visible then got the idea of the paper towel wrap. wah lah!
This sight had a list of leak location on my 03 but I don't think I printed it. I believe someone likely has noted other locales for coolant loss on your model year. Until you find it Carry coolant with you at all times, if it gets worse before you find it, you can be out of coolant quickly if the plastic further deteriorates. Cheers! Murph

 

[89Suburban]

I had similar issue with 03 Tahoe. I wrapped a white paper towel around both T connections going in to firewall and tied them on. There was a small leak from both that evaporated and never showed from looking on either side or from the grill, but the coolant showed up on the paper towel. If it is leaking in the summer it will get hot enuff after getting it up to temp and driving a bit further to verify if this is the location of your leak. I have found this method of locating them better than the smell test or looking for residue around the leak. I fought the leaks on the firewall Ts for months, there was nothing visible then got the idea of the paper towel wrap. wah lah!
This sight had a list of leak location on my 03 but I don't think I printed it. I believe someone likely has noted other locales for coolant loss on your model year. Until you find it Carry coolant with you at all times, if it gets worse before you find it, you can be out of coolant quickly if the plastic further deteriorates. Cheers! Murph

Yup carry extra coolant and I also have a barbed fitting spliced into one of the heater hoses with double clamps so I can bypass that whole she-bang in an emergency failure if it comes to it.

 

[opfor2]

Yup carry extra coolant and I also have a barbed fitting spliced into one of the heater hoses with double clamps so I can bypass that whole she-bang in an emergency failure if it comes to it.

What size "Barbed Fitting" did you use?

 

[89Suburban]

What size "Barbed Fitting" did you use?

I think it's 5/8". I have it located where those brass spring clamps are at on the right hose.

 

[opfor2]

I think it's 5/8". I have it located where those brass spring clamps are at on the right hose.


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Thank you...