wornoutsuburban

Hi guys... Have an 05 Suburban with 163k miles on it. Two days ago I noticed the temp gauge rising to about 240 deg while idling. Fans kicked on with no change. Then while driving the temp returned to 210 and stayed there. Happened a few times since. Never noticed that before in the past four years. When checking under the hood there was very little coolant in the reservoir.
Are these related? Assuming so.
I just added a quart of oil last week. It uses about a quart ever oil change or so. I do not notice any white smoke from the tail pipe. The oil on the stick is not milky, just plain dark brown/ black.
There's no pooling on the garage floor- ever.
What are your ideas?

73shark

Sticking t-stat, trash either in front of or between the A/C condenser and radiator, water pump failing, collapsed lower hose, clogged radiator, etc.

Check the underneath side of the oil fill cap. If it looks like gray jelly, then you're getting water in the oil.

SWHouston

Temporarily tape/tie a small jug/bottle where you can put your discharge tube from your reservoir in it. I'd like to know if you're loosing coolant by blowing it out that overflow, or through the engine.
Have you done a "sniff" test for Fuel Gas in the Radiator headroom ?

wornoutsuburban

No sniff test yet.
Dumb question... How do I know the difference between dexcool and the glycol coolants? I night this used and don't know if the previous owner changed it from dexcool or if it is original. I read you can't mix the two coolants.
Thank you for the help guys... Not mechanically inclined!

Joe In NY

Dexcool, orangish-red. everything else, green.

trainwreck91

could be that it's just low coolant since there is no leakage. simple thing first add coolant. if it's still happening, then like shark said the thermostat might be sticking. change that and give us an update.

heres a link on a how to

wornoutsuburban

Hey guys... added a gallon of coolant this morning. Staying cool so far. Will be observing for signs of leakage/ use. It seems to run great! Can you guys recommend those sealants, like Bar's Leak? Do they work? And is this engine just getting worn out? Should I be looking for something else? One more question, how hard can it be driven. I drive a lot and when my wife drives it, she drives it hard!

73shark

I wouldn't drive it much at all until I determined where that gallon of coolant went.

trainwreck91

as far as stop leaks go, imo i think most stuff out there is snake oil. some people swear by it but i think you should get a proper fix. not some genie in a bottle stuff. might do more harm then good

RichC10

Throwing a bottle of stop leak in probably won't hurt anything, and may seal a small leak. But before you do that, get a pressure tester from your local auto parts store, they lend them out. Mine had a small leak that I couldn't find. Put pressure to the system in the driveway and it should be easy to see if you have an external leak.