Coolant Leak after changing Thermostat?

[Dusty_GMT800]

I recently changed the thermostat in my 02 Tahoe, and now a couple days later, I noticed the truck appeared to have leaked a decent amount of coolant while I was working, over a span of about 3 hours. After it had been driven on the highway for about 20 minutes.
Is it possible that the coolant leaked through the top of the reservoir?
Drove it around a little bit between shifts and there's a small amount dripping, maybe a little bit leftover?
Aside from checking the thermostat was tightened down enough where else could the leak have came from?

 

[sumo]

Very possible. When I did my thermostat, I coated the gasket with some peratex hi tack to ensure a no leak. Did you use anything?
What you can do to make it easier to find is go to a auto store and pick up a coolant system pressure tester. Pump up the system the pressure should remain constant. If it drops, you have a leak but also will be easy to spot

 

[Dusty_GMT800]

Very possible. When I did my thermostat, I coated the gasket with some peratex hi tack to ensure a no leak. Did you use anything?
What you can do to make it easier to find is go to a auto store and pick up a coolant system pressure tester. Pump up the system the pressure should remain constant. If it drops, you have a leak but also will be easy to spot

The thermostat did have a gasket, however I didn't add anything on, will definitely have to try that out, might pull the thermostat next and put some sealant on the edges where it meets the block. It's weird because the leak didn't start until 4 days after I did the thermostat, and it was directly after the truck randomly puked up a bunch of coolant in the parking lot at work.

 

[PG01]

Got air trapped in there and it prob came out te overflow

 

[Doubeleive]

these thermostats come with a rubber o ring type gasket, you shouldn't have to put anything on it just make sure the surface is very clean, it's possible you could have squished or pinched it maybe during the install, when you check that be sure to check under the radiator for any leaks as well as the coolant will follow gravity and flow down, check under the water pump area also these pumps are known to weep out and if you see coolant on the bottom of the lower pulley or oil pan area that could be the source, also check over your reservoir tank real good these can crack and be really hard to see the crack and the reservoir cap has a o-ring seal also check that too.

 

[Dusty_GMT800]

these thermostats come with a rubber o ring type gasket, you shouldn't have to put anything on it just make sure the surface is very clean, it's possible you could have squished or pinched it maybe during the install, when you check that be sure to check under the radiator for any leaks as well as the coolant will follow gravity and flow down, check under the water pump area also these pumps are known to weep out and if you see coolant on the bottom of the lower pulley or oil pan area that could be the source, also check over your reservoir tank real good these can crack and be really hard to see the crack and the reservoir cap has a o-ring seal also check that too.

Is the o-ring where the housing mates to the water pump? or where the thermostat goes into the housing? I have seen some posts saying there's an updated housing that doesn't have a space for an o-ring.

 

[Doubeleive]

skip to 6 minutes and it should look like this, the outer housing may vary but this is a general reference, there may be a updated housing but I haven't seen one other than a complete water pump with thermostat built in and removeable housing was eliminated altogether.

 

[Dusty_GMT800]

It rained overnight so hard to tell if coolant is leaking now since the pavement is wet, going to go off of the reservoir for now. Although it doesn't seem like it leaked at all last night, coolant levels were the same. If it is leaking it definitely had to have slowed down.

 

[Chubbs]

You can't tell if the coolant exited the overflow? The biggest concern would be overheating if the air hasn't been purged out.

 

[Dusty_GMT800]

You can't tell if the coolant exited the overflow? The biggest concern would be overheating if the air hasn't been purged out.

It hasn't overheated at all. And I couldn't tell because I noticed roughly 3-4 hours after it happened. I was at work so didn't have time to pop the hood and look.