I have a 1995 Camaro z28. I have replaced the converer the brakes the discs the driveline and other interior stuff as well. Here is my problem my car overheated like all the time. So it would not pass emissions. So the converter helped and dropped two of the three issue that passed the third one was the NOX system that failed So my mechanic said my nox means that the engine is overheating (220) or the egr valve is failing, he said the egr would tell you is was bad by the engine running differently than it usual does like not idling or othe stuff. He said since my engine is over heating that's the problem. So I took out the one core radiator and replaced it with a four core and all new hoses thermostat. Drove it around and it was only at 180 temps.. So I drove it to emissions. And when they were running it on the dyno.. I watched the temps.. go up to 220 and was freaking out, thinking a coolant leak or something but no leaks and failed again same NOX issue. Well the old radiator got plugged from brown like thick muddy stuff, so I thought the new one would cure it. But it did not, now the new radiator fluid is starting to look like the muddy stuff is coming back! Is it my heater core that I need to replace or bypass??? Please help me if you have had an issue with this.

 

sounds like someone mixed orange antifreeze with the green stuff. your going to need to flush the heck outa the engine, might be a good idea to flush radiator as well, remove and back flush it. also flush your heater core. be a good idea to remove the heater hose with the restictor on it and back flush it while your doing the heater core. sorry but i would remove the steam line at the back of the heads and clean it. its a small metal pipe the runs from one head to the other to prevent hot spots that causes steam to form without it.

 

Could this be because someone mixed antifreeze?

 

yes, dont mix the green and orange antifreeze, it turns to gunk.

 

I would bet the EGR is what is causing it to fail emissions. The whole purpose behind the EGR is to low NOx emissions and that's what you're failing for, though the vehicle running hot can add to the problem. Does it get hot during normal driving or just when they're doing the emissions test? Do they have air blowing through the radiator and/or do your fans kick on?

 

I believe your car came with 195 thermostat, the fan turns on low at 226 deg and steps to high at 235. 220 is almost perfect running temp. Someone is clueless.

 

3.8 came with 195, lt1 has 180 at least mine is 180 stock. runs at about 185 or so.

 

So because you put a 180 thermostat in the engine the a radiator on a dyno with no air passing over it will keep your engine running at 185? That kind neat, you don't even need fans.

You can take out the thermostat and it will still keep getting hotter until the fan comes on. On a dyno you not going to go below the turn off of the fan.

 

honest the lt1 has a 180 thermostat stock, and both my 93s temp has set at or around the first mark. 4th Gen LT1 F-body Tech Articles

 

True for LT1, 180° stat
https://www.rockauto.com/en/catalog/...hermostat,2200