Hi all, before I get started I wanted to thank anyone taking a look at this page for any insight they may offer, and I hope a solution here can help some folks in the future. Ill start with the symptoms and action taken so far.

I started heading home from work today and noticed that my motor got up to temperature unusually quickly. I kept an eye on it making a quick stop before hitting the highway, and at the first stoplight I had very minor smoking and at the second light it had progressed, the temp gauge jumped towards the last tick towards the top. I pulled off the road immediately and shut her down to cool off, and found a weird spatter of fluid in the engine bay. It was on top of the engine and I had a friend tow it back to my house with a uhaul trailer. Oil was good and I put about a gallon of coolant in to top it off, and in the short spurts of running to get it on and off the trailer my friend had noticed a leaking point on top of the throttle body. Ill post two picutres with the perspectives and a third looking at the general buildup around the problem area.






The small silver disc that's popped up and offset is letting coolant through, hissing while the motor is on and letting out what I can only describe as a chipmunk farting. It doesn't have any give at the moment in its current position, and I was wondering whether a repair or a replace would have to occur. I've seen reman/new units on rockauto but another option I see are salvage cars on car-part.com on units less than 60k miles ever used, most less than 100$ for a supposed OEM unit. Id like to hear if anyone has advice moving forwards, right now I stand at getting a salvage throttle body, replacing all the rubber hoses involved, and then investigating the thermostat just in case.

2002 LS3 204,000miles

 

If you didn’t overheat then you just need to fix the coolant leak and then refill the coolant. The throttlebody has a heating circuit to get it up temp in the winter and it looks like the heater hoses on your car have been replaced with just some generic hose. Get some proper sized coolant hoses and replace then pressure test the cooling system to make sure it’s air tight and will hold pressure. It’ll be ok

 

Thanks for the quick reply. I do plan on replacing the hoses with correct/new ones as part of the repair however the disc that's been ejected outwards isn't something I can press back into place, and as soon as I figure out the course of action for that I can start ordering parts. From what I read online it can pop out of place due to pressure in the cooling system. Do you think taking the throttle body apart to fix that piece would yield any useful result?

 

I am not sure what that thing is, I can tell you that a lot of people will bypass the throttlebody coolant circuit completely. My car is a generation older than yours so the throttlebody is different. That disc could be some sort of a bleeder or something? My throttlebody was the high point for the cooling system so it came with a port that could let any air that got trapped in there. Can you remove those hoses and take another picture of the disc ?

 

It's basically a freeze plug. A good machine shop might have one but finding the exact (likely metric) size might be tricky.

 

Can you elaborate on this heating circuit?
Maybe show a pic or a diagram..?

 

Here you go.

 

 

I was surprised to see that the duo in that linked video had similar mileage and was a prefacelift ls3, same as mine. I ended up following what they did and it was pretty gratifying, it was the first time Ive used JB weld.

I noticed the images are very large on the forum so ill put the results in a spoiler for readability.

Overall only had one casualty, the vacuum switching valve. The PCV hose came off with little issue, however when removing the evap hose the VSV exploded. :/
I noticed the coolant slow leaking around this plug before it failed, and I plan to update you all in the short term and long term with how it holds up! Thank you guys for the info and time.

 

The freeze plug popped out maybe due to old and weak coolant mixture.

The throttle body freeze plug is there to protect the throttle body from damage due to coolant freeze over. Now since you glued the freeze plug shut, make sure to change the coolant with a proper mixture of antifreeze and distilled water, 45/55 ratio is preferred

 

Doing some searching around it's speculated that Plug is from when Toyota manufactured the throttle body they bored out that cavity to then create the pathways for the coolant then they just plugged the remaining hole. Another fix some have done is to drill out the hole and tap it for a 3/8 Pipe Plug.

 

Same thing happened to me a few years ago. Mine had completely popped out. I cleaned the area , used a socket and hammer to tap the plug back in, then used a center punch to stake around the edges to ensure it didn’t come back out. Ive put over a 100k miles on this repair.