Noticed my car is running hot. I have a 160 thermostat and it used to cruise at 160 on the highway and when it reached 230 in stop and go traffic, the fan would kick on and drop it down to 210 before it rising back again and or getting on the highway to drop it back down to 160. But now when im on the highway it wont go under 190 and will slowly creep up to 210 and just stay there. Now in stop and go traffic it goes up to 220 and slowly rises to 230 before the fan kicks on and keeps it at 230. I replaced the thermostat, water pump, radiator, radiator cap, and even flushed some of the cooling system cleaner through it with fresh coolant and still nothing. This is driving me nuts and im getting ready to stay screw it and LS swap the damn thing. Possibly throw the 350 in something else.

 

Seems like it was running normally before. I'd put a factory thermostat back in.

 

it ran perfect with the 160 in it, and I’m using a new 160 thermostat. Even if I threw in the factory 180-190 thermostat, it probably would still act the same

 

Does your car have the factory air dam? Is this a single or dual fan setup? Was the outside temperature the same before chsnges were made or was it in coolef weather? Why are you waiting until 230F to turn on your fans. You can get a low tempersture fan switch and altered tuning to turn the fans on much earlier.

 

So the 230 fan switch is the stock one, im currently in the process of getting a colder one. This is a dual fan setup. Only one turns on which is the ECU controlled one, the temp switch in the passenger side head doesnt turn on at all, i dont think it gets hot enough to which is why im getting a colder one. And yes my car had the factory air dam. And the weather doesnt matter because it ran perfectly fine for the months of may and june.

 

Alright so I made another discovery. So I know my radiator is working because I grounded one of my cooling fans and had it run continuously and noticed it didn’t get above 200. Now that’s at stop and go traffic and cruising on the highway. But when I turned it off and ran it on the highway, it started to creep up again. So now I’m thinking it’s an airflow issue. I have the air dam and all three pieces intact with no blockages. I also took out the ac condenser in front of the radiator so now it’s a straight shot through towards it. I had no thermostat in it and then put the new 180 back in and it still behaves the same. So now I’m even more stumped.

 

Gauge may be off.

 

 

^^^^This.

What are you using to determine the engine's actual operating temp? If it's only the dash gauge, they can be notoriously inaccurate. Obtain an inexpensive infrared temperature gun ($12-$20) and see what's really going on.

 

My car had a similar issue. Once it warmed up it would get hot I could watch temp gauge move at stop lights. I tried replacing the fan switch, t-stat new coolant hoses and even Prestone radiator treatment. Running the heat and the AC helped a little.

Replaced my radiator, a new Delco solved my issue. I did that last even though I had pulled mine radiator and ran the garden hose through it and it seemed to flow fine. It ran considerably cooler after that and the OE was only about 10-12 years old at the time.

 

So i have a mechanical gauge since my dash one went out. i also bought a temp gun and it reads around the same as the mechanical gauge. Now im currently running my cooling fan switch always grounded. it seems to cruise around 190 to 200 now at any speed. Highway, stop and go, etc. Could a bad heater core possibly cause this? its the one thing i havent replaced yet

 

4 questions:

what happens when one fan on, one fan off sitting still
what happens when one fan on, one fan off going down highway
what happens when both fans on? sitting still
what happens when both fans on? going down highway?

more questions:

Are you certain your water pump is working? Can you see it exchange coolant?

Does your radiator have the foam insulation on the sides which forces air thru it, rather than letting air slip around it?

 

GM wanted these motors to run hotter for exhaust pollution reasons. I am running a 180 or 185 tstat (whichever). If your car runs better/cooler stay with the 160*. My '72 Buick GS factories for 195* tstat which meant the engine ran well over 200* I replaced with a 180* & and all was well.
The Buick engines have a lot of nickle in the blocks & can withstand heat far better than the chevy blocks.