overheating, what can it be?

[autobahNESSA]

Okay here's the deal, I got an sr. stop 'n go traffic no problem. can drive it for hours in it, flooring it. Freeway runs, no overheating as long as below 3k. Car go for 2 hours with no overheating. Freeway above 3k for 1.5 hours, and then it starts to get warm. Driving hard in the mountains 20min, the car is overheating.- or really hot.

Have new water pump, the thermostate is working because the lowe radiaor hose gets hot. 50/50 mix of anti freez and coolant. The thing is wierd the most is it only overheats when the turbo is constantly spooling. I thing above 3k the turbo is makeing some boost even when im just cruzing. I am not sure because i dont have a guage. So what can be causing my engine to overheat?

[FastBack 240]

Did your radiator take a dump? Any clogs in the engine?

[autobahNESSA]

How would you be able to tell if you have clogs in the engine?
Thanks

[240Stilo]

Originally posted by bayarea240
Have new water pump, the thermostate is working because the lowe radiaor hose gets hot.

Explain how the radiator hose being hot signifies the thermostat is working again? I might be wrong but I never heard of that.

[nrcooled]

Hey bayarea,
Post your setup so we can help you better
FMIC?
Stock Rad?
Clutch fan?
Electric fans?

Have you bled your coolant?

[autobahNESSA]

my setup is a stock sr

stock fan shroud, stock sr radiator, stock fan clutch.

the coolant is brand new, has less than 2000miles in it, thier is no air in the system, ive bleed the air out many times, and the last few times, no air bubbles surfaced. the coolant has not changed anycolor, it looks new, from draining, and the top of the radiator.
This is why I cant figure out whats wrong. unless i got some passages in the head clogged, but wouldnt that cause the engine to overheat during stop and go traffic also? Are their any additives that any of you reccomend that will clean out the cooling system?
Thanks

[nrcooled]

Goto Any auto place and have them compltely flush your system. There is a machine that pressurizes the entire system and blows any and everything out. Hopefully it will be a easy fix and not a big problem

[einherjar]

um, have you checked your oil? cause it might be, something bad, like a cracked block (do you notice it overheating faster and faster?) my 240's block is cracked, and it was only overheating everynow and then, but now it runs like ****, so i'm upgrading!

[autobahNESSA]

Thanks nrcooled I'll try that when i get some money

Naw the block isnt cracked, i did the swap myself and the block was fine. compression is good. It doesnt eat oil, it drops a little though, but that is from a different problem that I already knew about.

[kalieaire]

test or replace your radiator cap.

[thx247]

if the thermostate is not working right the water does not circulate, and the lower radiator hose never really gets warm.

This problem sounds more like a bad gasket or something. The radiator and thermo are working, in theory there are no bubbles.


What happens when you turn the heater on when the car overheats? Do you get warm air? can you cool the car down ?

[UcanTry]

youve got what year sr in what year 240

[scandalcat1]

this may sound odd, but there are a couple of things which can cause overheating. it might have been stated before but i will re-iterate.
1. thermostat/ possibly blocked open or closed and even malfunctioning
2. hoses/ cracks and small leaks even squishyness
3. fan engagement and temperature sensor/ is it turning on when it is supposed to?
4. the weird one, fix any radiator fins that are bent and check for debris/ bent fins impede proper air flow and also dead bugs and some foliage

i usually check the antifreeze with a chemical test to check for corosion or oil. drain/flush the system, then add your 50/50 mix and then some super cool, which is a compound which works with the anti-freeze to drop temps from 10 to 20 degrees. i buy the stuff at pep boys for $20 a gallon, its usually on the top shelf (at least it was in 4 stores) in the additives section. yes, it is safe for water pumps.