I recently just bought this car from a guy on craigslist and i brought it home and didnt drive it for about 3 weeks.when i did start to drive it it started overheating fairly quick even if it was setting still.so,i changed the thermostat and that didnt help at all.then the local parts store suggested changing the water pump.so,i did and the old one did look really bad and the thing almost was falling apart inside it.same thing still over heating.so i flushed the radiator to see if anything may have been clogging it up but that didnt help at all.
one question i do have is a guy from a local shop had mentioned that there is a valve on the water lines of these cars that runs back to the heater core from the water pump (i had noticed it while changing the water pump but,wasnt sure what they were for)he was saying that you have to bleed the air out of the system or else it will not circulate right and still over heat anyone have any input on that?
head gaskets are ok so i had eliminated that as well.
anyone who can help me it would be greatly appreciated.Thanks in advance.

 

yes, you have to bleed the air out and make sure the fans are working.

 

fans are working good the guy had even wired up a switch so u could turn one fan on manually if u needed it.

any ideas on the best way to bleed that off without gettin burnt?

 

i just open both valves while filling the radiator. once i'm done filling it up, i start the car and open the valves one at a time till coolant comes out.

 

There are two hoses over the top of the water pump. In plain view. There is a screw on each. These are the bleeder screws. Crack them open until coolant begins to come out. Start engine and watch the coolant coming out around the screws until air stops and only coolant comes out. Tighten the screws back down. Top the radiator off when it's cool enough to do so. You may have to top off two or three times.

 

have any of you ever heard of air in those lines making a car overheat?

 

yes, air can cavitate the pump or flow, you can get alot of air out then get a bubble from the heater core. If there is a leak any were you can be adding air when your engine cools off and sucks air inside as the water contracts.

 

thank you ill be trying it in a few minutes i hope it helps.

 

just when you think you have all the air out...theres probably still more lol. It always happens to me and the slightest amount of air will cause the car to overheat. I like to open up the bleeders, put a long funnel in the radiator, and fill the coolant to the top of the funnel so the coolant level is higher than the bleeder valves. Seems to work a little better

 

Are you sure you have the correct thermostat? The LT1 can not use a "generic" t'stat, and requires one made spcifically for the LT1's reverse-flow cooling system. Shoebox has a lot of great info on the cooling system, bleeding the air, and the correct t'stat:

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

http://shbox.com/1/tstat.jpg

 

There are some great suggestions on here. If all these fail....One final idea, you may exhaust all these only to get more over-heating...if so, a radiator replacement may be the only fix. There are many reasons why these LT1 radiators block up; it takes about 120,000 plus miles before it fails due to internal blocking...or a bad combination of old and new(permanent) anti freeze and radiator flush chemicals. Most new anti-freeze is factory diluted with distilled water to prevent any cross contamination....this helps only in some circumstances.

 

Ditto what Injuneer said. Also be very careful with those bleeder screws cuz they are prone to break off easily and some people have resorted to a mod to eliminate them.