Coolant Leak after changing Thermostat?

[Chubbs]

Some of the air would have purged simply through the heating and cooling process but a proper bleeding is what's called-for. I would start off with that and have my OBD reader plugged in to monitor the coolant temp in real-time via the "live data" mode or equivalent. I know that my truck has an operating temp of 190-deg. if I were to see any fluctuations higher than that it would be attributed to the presence of air, continuing the bleeding procedure until I have a rock-steady temp @ idle. You can find the proper instructions from a thorough search. Something like engine idling, front elevated, expansion cap removed, alternate RPMs, ignition off & allow engine to cool. Then repeat. Just an example.

 

[Fless]

Bleeding process in this thread, post #6:
https://www.tahoeyukonforum.com/threads/coolant-problem.99389/#post-1188519

 

[Dusty_GMT800]

Well it's not overheating at all, so I don't think there's any air in the system, I'm going to try to remove the thermostat on the next warm day I have and see if I need to sand the surface a little better, might put a little gasket maker around there for good measure.
Just hoping it isn't the water pump.

 

[Dusty_GMT800]

I've noticed that it really only leaks right after I drive, the truck sat for 3 days since Christmas Eve up until now and it hasn't leaked then. But today after driving to work it leaked a puddle in the lot once again.

 

[Doubeleive]

pull it out and take it back and exchange from wherever you bought it, tell them it leaks as you described maybe it's a manufacture defect, maybe the o-ring is funky, who knows.

 

[Dusty_GMT800]

pull it out and take it back and exchange from wherever you bought it, tell them it leaks as you described maybe it's a manufacture defect, maybe the o-ring is funky, who knows.

That's what I'm going to do as soon as it isn't 10 degrees out haha, this winter has been brutal so far

 

[sumo]

It’s only leaking after driving is because there’s pressure built up. The housing itself dosent have a gasket from what I remember. The t-stat itself has a rubber gasket that sits in the housing. You don’t need to use any sealant if the surface is really clean. I use hi tack because coolant can leave a crusty residue build up around the mating surface of the housing. Sometimes you may think you cleaned it all but you may miss a small amount which can be enough to all allow the o-ring to fit properly or housing to fit flush. Using a sealant can prevent that.

 

[shoplizard]

There is one thing you might check is the little hoes that attaches to a nipple on the passenger side of the radiator near the top. Remove the hose carefully and check and clean the inside of the nipple on the radiator. Add some coolant to the reservoir and verify that coolant and air come out of the hose. Reattach the hose the hose and fill the system with coolant. This hose bleeds the air from the cooling system while filling if it is restricted by gunk inside the nipple, it will cause the system to retain air and cause the burping of coolant out the reservoir after reaching operating temperature.

 

[Dusty_GMT800]

It’s only leaking after driving is because there’s pressure built up. The housing itself dosent have a gasket from what I remember. The t-stat itself has a rubber gasket that sits in the housing. You don’t need to use any sealant if the surface is really clean. I use hi tack because coolant can leave a crusty residue build up around the mating surface of the housing. Sometimes you may think you cleaned it all but you may miss a small amount which can be enough to all allow the o-ring to fit properly or housing to fit flush. Using a sealant can prevent that.

That makes sense, what grit sandpaper would you recommend using to clean up the surface? It's supposed to be warm this Wednesday so I was going to drain the coolant again and pull the thermostat to clean everything up.

 

[Doubeleive]

I wouldn't use sandpaper unless you can see or feel something on there that absolutely will not come off any other way, but that's just my opinion