my car gets hot after running 15 to 20 miles on highway...all stock 305 tpi..with jet rad fan switch..that kicks fan on at 200 off at 180...new t-stat..fans both come on...never gets above 220 but it never ran this hot before

 

is the airdam is place?

 

yes it is

 

200, why would you want your fans to come on this late; i have mine with a 185 temp switch and its still getting hot........
im thinking its the fans on mine though

you sure ur fans are coming on....

 

Generally speaking, if the fans are coming on and you get hot just going down the highway, check coolant level and thermostat. Is there water in the upper radiator hose? If so then, thermostat should be working. If air dams are in place, looking to the water pump to be the problem.

 

coolant level is good and brand new thermostat...i have good flow with my water pump...and my air dam is in place....both fans work...my rad cap wasnt holding pressure so i replaced it....also i noticed i have lots of bubbles in rad when running with cap off...what is that?..like it has air in it?

 

Funny that you mention that. My car just started doing that too.

It will run real hot on the highway almost to the point of overheating but if I pull off the highway and drive in the city the temperature goes down. It has plenty of coolant, 180 thermo, which is pretty new and the fan is rigged to be on all the time. Any thoughts?

 

Worn out waterpump impeller, or 'slight for now' blown head gasket. Get a Compresion check done and you will know for sure. The weep hole may not be fully exposed yet on the waterpump and it only leaks a small amount when driving.

 

I prefer the first one. Now that you mention it, you maybe right about the waterpump.

Pulleys sound like crap until you spray them with a little silicon. Sounds squeaky but not the normal belt squeak more like metal on metal squeaking.

 

Fans are automatically turned off when you're driving over 40 mph. So fans are out of the question as far as highway overheating (unless you have a manual fan switch and are leaving them on.....that actually reduces cooling)

Air dam is good.

Checked for crap between radiator and condenser? Is this with or without A/C? What kind of outdoor weather temp/humidity are you dealing with?

 

make sure your air dam is on tight and not weak bending easy mine was the same way i would look at my air dam and it looked fine till i would push it back you shouldnt be able to do it so my car runs great now

 

I would check the Airdam first, because it is not cooling at highway speeds and the fans are doing the cooling in the city driving.

 

No airdam on my car and it runs fine on the high way.

 

Fan is running at all times. Air dam is fine. Temperature down here in So. Fla is the same as it is every year at this time....low to mid 90's, humidity 100%. Car ran hot either with the a/c on or off. Didn't matter although I noticed that the a/c began to blow hot air once the temperature got pretty hot.

 

Another simple idea is a partial blockage in the radiator. A radiator shop could do a pressure check and leak down on the rad or just pull it and have them service it anyways.

 

I just went through this on the L98 in my 89 Vette. The bubbles were the sign of a head gasket beginning to go. Hopefully your bubbles are just air bleeding out of the system, but I second the compression test and a pressure test of your cooling system to know for sure. Take a peek at the oil as well.

 

I shouldv'e thought about this earlier, but call around a couple of shops and see who is closest to the house that has a Five Gas Analizer. If you can get the car to them without building up much heat, they can pop off the radiator cap and stick the analizer pick up tube in the radiator opening. If the head gasket is blown, that machine will tell you right away. There will be exhuast fumes coming from the coolant!

 

You can also buy a kit from NAPA ($50) that uses a blue fluid to test for exhaust gases in the coolant. Some of the stores may also loan or rent them.