Just had the cats gutted and my car started overheating like crazy. Before I gutted my cats I installed spark plugs, new coil packs, and a thermostat. Also I replaced the left valve gasket. It had a p0300 code and the misfire went way after I gutted my cats.But after the gutted cats it’s been overheating. I get up to about 50mph and the temp gauge will spike up and all of my radiator fluid would be gone or at least low. What do I do??

 

Did you burp the cooling system after changing thermostat? How did you do it?
Does your heat work?
Are your cooling fans running when the car temp gets hot?

 

yes I put blue devil in as the last choice I had and did the full process without need to burp it a second time as the bottle said. I test drove it after and the car seemed to be running better even when I got up to 70MPH. When I got back after a 25 min drive/idle, I drive onto the driveway while I’d a kinda steep hill, and the car shoots up on the thermostat.

 

I'd get that blue devil **** out as soon as possible unless someone here can back it up. Never heard of it and it sounds like a gimmick after a quick search. I'd be worried it will gunk up the entire system, heater core. These cars can be tricky to burp without the Lisle spill free funnel.
Again, are your cooling fans on when the car overheats?

 

if you’re standing in the front of the car the right one works well but the left one doesn’t spin, it’s never really spun as far as I could tell and I’ve never had a problem out of it

 

They should both be on high speed when your car reaches a certain temp. I think it's 204°
Edit: just saw you have an 03. The first models had mechanical fans. Do you have mechanical or electric?

 

but that shouldn’t cause the car to smoke though, my oil is good but I can’t read it on the stick due to it being all over the place.

 

You never mentioned smoke. When the car overheats, coolant expands and will come out of the overflow tank

 

And to check your oil, it's best to let it sit overnight. You will get a clean reading

 

I have mechanical fans, and yes I had steam coming from the exhaust not smoke, I’ve seen headlights flash through the smoke one day and it was blue and white.

 

could it be a leakage around the radiator where the plastic meets the metal?

 

Doesnt sound good. Usually a blown head gasket will cause coolant to mix with the oil and the coolant evaporates causing white smoke from exhaust. And overheating will cause a blown head gasket

 

Why did you use Blue Devil? That's a last resort to buy you some time if you have a bad head gasket.

 

Sounds like you didn't properly fill the coolant system and had a bunch of air trapped in it, went for a drive, overheated and blew the motor.

Start with a compression and leakdown test to make sure it's worth investing time/money into fixing what's wrong.

Follow the FSM steps EXACTLY about how to fill the coolant system on these cars, this isn't an old pickup truck that you just dump in a bunch of coolant and drive off into the sunset worry free.

Does your heater blow hot air? Are your spark plugs wet? Did you open the coolant purge valve?

Drain that blue devil out or you're possibly going to be tearing the dash apart to replace a heater core or radiator. That stuff is designed to work long enough for you to drive to a shop to get the problem fixed, it is NOT a permanent solution.

 

Also, hollowing out the cats has absolutely zero effect whatsoever on coolant temperature.