2001 Suburban / 6.0 / 2500 / 4x4 / ................ Hi Guys, new kid here. My name is Austin and I could use some help from those of you out there with some first hand knowledge of the 6.0, .------- where would my "coolant" be going if there is no spots on driveway, no wet spots ANYWHERE on any hoses, connections, cant find leaks anywhere, to include the rear (also has rear heat & air). There are zero signs of wetness, however, I don't loose coolant quite as fast without the AC on.
But on average, I'm filling my coolant bottle every 25-30 miles or so.......????????????????????????????????????? More so on hot days.
If this pops up twice, I'm sorry, I put it in earlier and never saw it appear, so I thought I'd try again.
AJRYAN1964@yahoo.com

 

Austin, sorry for all the trouble in accessing this thread...

First thing I'd do is do a Fuel Gas (sniff) test on your Radiator.
You can buy a little tester at most Auto Supply, or drop by a Radiator Shop, and they may do it for you for free.

 

Thanx, did it today. Passed. Anything else you can think of? Man what a head scratcher!

 

That Fuel Gas test is the first thing one should look at, when you loose coolant and there's no external evidence of where it went.

Beyond that, there are several things which may cause it, first being...
A sluggish Thermostat or weak Radiator Cap. Loss happens when you are driving along and stop quickly, and a "surge" in temperature occurs. One or the other doesn't keep up with it, and you loose a little coolant in the form of Steam, or a spurt of it out the overflow, neither of which you see.

After the test, those would be next to address.

 

if you are losing coolant, with no identifiable leakage, it could be leaving through the tail pipe.

if there's an issue w/the head gasket seal, it's going to allow coolant into the combustion chamber, and then it goes out the back.

any sweet smell in the exhaust? white exhaust?

I'd compression check the engine. see what that shows.

 

i don't remember if it was just the 5.3 or if it included the 6.0 that i heard about having issues with hairline cracks in the head causing coolant loss, but most of those are very slow leaks. this seems way to fast for that. I've seen a lot of these motors with water pump leaks sometimes the coolant dries on the motor so you don't see it hit the ground. i would check not just for wetness on the motor but for dried pink crud.

 

FOUND IT!!!
So dig this guys.... the coolant line running along the frame back to the rear heater core found a way to rub itself on the fuel tank seam, causing a hole to get worn through. The crazy thing is.... it dripped straight down onto the exhaust pipe..... instantly becoming steam and , "poof", all gone.
Then, as fate would have it.... G.M. doesn't make or carry that particular line any longer. So I just bypassed it at the firewall. No more rear heat.....but hey, I don't sit back there

 

Oh, and thank you all for your help.

 

Thank you for the report on the cause - and GREAT job finding that!! Poor folks in the cold back though lol