Overheating issue 2014 5.7

My 2014 5.7 is overheating but I can drive it for an hour with the heater on full. When the truck has cooled down I slowly started to realease the radiator cap and the coolant reservoir starts to bubble badly, like a pot of boiling water. I just bought a thermostat but I'm concerned about the bubbling reservoir. And I just got a tuneup yesterday.

 

What’s a tune up?

 

Replaced all plugs and coil for #4. So not really a tune up.

 

How long have you had it? What have you done to it? What were conditions driving it??
Welcome from VA

 

Bad thermostat or water pump?

 

What condition is your radiator cap in?

 

Sounds like a bad radiator cap, common problems on the 5.7s

 

Things to check, radiator cap, waterpump functon, fan clutch and of course any signs of leaks.

 

I've had the truck since 15'. Besides a bad alternator this is the only major issue I've had. I have 306k on it so I'm leaning towards the thermostat and will be replacing it regardless. I'm actually considering buying a used motor just to have on hand. I figured I'd buy one now before prices get out of hand.

 

It's good.

 

I did find a pinhole leak in my muffler.. other then that nothing.

 

Since I've never replaced the thermostat and I have over 300k that will be replaced.

 

So the Thermostat has been replaced, radiator fluid replaced and the truck runs good for the most part except the check engine/traction control off warning is back.

Here's the thing. When I start it cold the engine misfires/shakes leading to a blinking check engine light. I then wait for the engine to warm up, the shaking goes away then turn off my truck. When I start it back up the check engine light is no longer flashing but solid and no longer misfires.

Im thinking that I have a small leak in the headgasket. Any thoughts?

Has anyone had success using an additive to seal the headgasget. If so, how long did it last and is there any downside?

 

Paul from FabRats poured this in his Tacoma and says it has held for a couple years. It will put a nasty coating on everything it touches.

 

Use OBD2 codes to find which cylinder misfires. Test compression, look inside spark plug holes with boroscope camera, you can see a difference inside compared to other cylinders. Then you might even see the leak too, Test coolant for exhaust gases, etc. No need to just guess it has a blown head gasket.