Really weird over heating prolem

[twiztid ryda]

I have this really weird problem, I was recently driving my 92 GS n/t and it goes fine for awhile, now after awhile in stop and go traffic it starts to over heat. Now before it over heats I can run up to and over 4000 rpms, but once it gets to the 75% mark it wont go past 3500 rpms. Once it over heats it wont be back to normal until I let the engine completly get cold, like next day. I thought it was my valve cover gasket and had it replaced because there was some oil getting into the spark plug well. But now just whenever it over heats it starts jerking bad. Is there anything you can tell, and yes I changed the thermostat and made sure the coolant is in. Have you ever come across this problem before? All your help is greatly appreciated.

twiztid ryda

 

[koenigseggCC7]

im not sure if this will help but it sounds somewhat related:

one day i was driving and my rpm's drop to 0...timing belt snaps...replace the timing belt, a few days later same thing happens...rip apart the motor to find out the timing belt is wearing wonderfully...let the car cool n it starts up n runs great...i was low on coolant and it overheated and stalled itself out...hasnt happened in a week or so, so i dont think it was anything other then that

 

[streetraceboi]

if you have an overheating prob, the first thing you should NOT do is drive it when its overheating, due to our cylinder heads cracking when this happens. if you have a cracked head, usually water/coolant gets into the head and causes the oil to get milky so you might wanna check that. also, could be a blown headgasket. if its the water pump, the way i know of checking it is to take off the belt and moving the pulley up and down and check it for play, if it has play it needs to be replaced. are your fans turning on? you might also wanna check for any punctured or torn hoses which usually cause a car to overheat slowly. just a few things you need to check. and again, do NOT drive the car when its overheating

 

[streetraceboi]

you might also wanna do a compression test to see if you have bad rings, or a cracked piston which can also cause overheating

 

[jott5555]

check the norms.. thermostat, headgasket, waterpump, proper coolant mix, hoses, leaks, heater core, and lastly make sure you have no air bubbles in the coolant system.

just a start

 

[twiztid ryda]

if you have an overheating prob, the first thing you should NOT do is drive it when its overheating, due to our cylinder heads cracking when this happens. if you have a cracked head, usually water/coolant gets into the head and causes the oil to get milky so you might wanna check that. also, could be a blown headgasket. if its the water pump, the way i know of checking it is to take off the belt and moving the pulley up and down and check it for play, if it has play it needs to be replaced. are your fans turning on? you might also wanna check for any punctured or torn hoses which usually cause a car to overheat slowly. just a few things you need to check. and again, do NOT drive the car when its overheating

Thanks for the pointers, I would not drive it when it overheated, I would pull over and let it cool down, if i saw it going into the hot zone i would find the expressway and cool it down. I thank everyone for their advice!! Going to start doing some testing.
thanks again.
twiztid ryda