Alright, my LT1 has been overheating.. After 30 mins of stop and go driving I've let it get about as high as 225-230*F Usually during a idle.

When I first got it hot I replaced the thermostat and radiator cap. (Radiator Cap from Chevrolet, 180* (stock right?) tstat from O Reillys.)

It's still overheating, today I replaced the thermostat with a 160* Hypertech from Autozone (Specially Ordered, yes I'm sure its for a LT1). and flushed the coolant from the bottom of the radiator.

I flushed the coolant from the radiator... filled it up with water, and then started it up, let it heat up making sure it had water. I eased it up to 2200 rpm and my dad topped off the water and closed the cap. I then made sure my system was empty of air. (I'm pretty sure) and took it back down to a idle and shut it off shortly thereafter.

I didn't drain the block, just the radiator... so I think it has about 20% coolant, 80% water... I think I got about 1 1/2 gallons out. (6 quarts - cololant capacity is 14.1 Q IIRC)

Any ideas? The fan (lower DS.. that's high right?) DOES come on, atleast when the heat is on. That usually helps it cool down...

- Should I let it idle and check when the fans come on? The upper / PS fan is low and comes on at 226* The lower / DS fan is high and comes on at 235* right?
- Is my radiator clogged

Thank you for any help.


Moderators: I put tihs in LT1 Tech due to the fact that it has Reverse Flow Cooling, I'm sorry if I put it in the wrong section.

 

Maybe there is still air in the system -you don't sound to sure that the proper air bleeding procedure was followed.
If you didn't bleed it from the 2 bleed screws through a few cycles do that before anything else.

Shoebox has a great write-up on the complete procedure.

http://shbox.com/1/4th_gen_tech2.html#radflush

 

a few cycles? Like 3 times 'till coolant comes out? should i let it cool between cycles? or what. I have to take the elbow off every time and disconect the MAF to run speed density.

 

I bled mine 3-4 times. Brought it up to temp, bled it, let it cool and repeat.
I would swear that I didn't have to take my elbow off.

 

If it gets to 225°-230° at idle and the primary fan comes on at 226°, that sounds exactly normal. I assume you have the 2 relay fan system from your description of the fan operation.

It's going to heat up at idle and car not moving. That's what cars do that have electric fans.

 

Thanks for the help, I don't know if I have 2 relay, I'm a electronics noob when it comes to cars. The coolant sensor is the 2 way. (PN 10096163) Don't know if that helps. I guess I will flush my water and put a good mixture of 50/50 then get my pcm tuned for a 160* stat.