so i bought a 03 civic ex coupe recently and when i was coming home from the highway my engine was smoking and i saw coolant on the left side of the engine the car didnt over heat. i also realized after this that the car got the filter that connects to the throttle body but no filter out that one. i think theres more to the problem then that tho idk where to start i never heard or dealt with coolant shooting out of a air filter so if anybody can give me some wisdom i would very much appreciate it. thanks!

Are you referring to the location where the air intake connects to the throttle body? Check the coolant bypass hoses underneath the throttle body flap/opening..maybe they are torn or split.

Are you saying the air filter is missing? If, it's missing ...put a new one in.

Yes it has the air intake but not the air filter I need to get a new one and I will very soon I just noticed last night...I can't believe I didn't notice earlier lol but I did more looking and took the air intake out and it was clean so the coolant isn't coming from there it's actually the thick metal line that connects to the thermostat. I'm guessing a gasket from the line to the thermostat went bad. But thanks for the reply man I appreciate it!

How many miles on odometer. If, you just purchased it you should consider replacing all or some of the coolant and heater hoses... inspect them visually and with your hand (when cold) for weak points. Overheating due to coolant loss can easily cause a blown head gasket with these engines (and most aluminum engines). If you there is any oil leaks on coolant hoses that will deteriorate hoses quicker as well.

173,000 on body 85,000 on the engine. And I will definitely will check them hoses asap if one of them things are going I'm sure there's another waiting to go soon. Thanks for the tip man!

You are about to learn why the previous owner got rid of the car!

(head gasket)

Yep thought that was the case but thankfully just a thermostat leak

Check the radiator coolant level and the reservoir level daily for the next week or more. If you losing coolant in radiator and gaining coolant in reservoir without any noticeable external coolant leak then refer to ezone's reply (headgasket). Hopefully, that's not the case.

Also, at 85k engine is due or near to a timing belt replacement if one hasn't been done yet. If/when you replace the TB it's a good time to replace the waterpump and thermostat too.

Yes I think the thermostat is bad and I will definitely check the others thanks for letting me know

Oh that hurt...

i have a funny feeling you are wasting money on a thermostat, it is not uncommon for these thermostats to last the lifetime of the vehicle, i also do not think that is your problem.....but its your dime

Did you see OPs other thread?

https://www.civicforums.com/forums/36-mechanical-problems-vehicle-issues-fix-forum/368983-coolant-leaking-out-back-thermostat-housing.html

Apparently it already got a head gasket by some hack who thought bolts weren't all that important.. Mr Goodpliers, if you will.

Maybe the cost to fix the botched work pushed the previous owner over the edge...