I was wondering if maybe you could help me out. I recently purchased a 1986 Nissan 300ZX non-turbo for use as a beater/daily driver. The car has been overheating since I bought it. So far I have flushed the system 4 times, replaced the thermostat, radiator, radiator cap, and a ruptured lower radiator hose. The car is still overheating, even after having done all of that! I’m at wits end with this monster! What could possibly be causing it?? The previous owner believed the car has a blown head gasket.
However, there is no transfer of fluid between oil and coolant, and no smoke coming out of the tailpipe, and other than getting hot, it runs like a champ. I don’t know where to look next and it’s driving me nuts!
Hey there Joe,
Get a cooling system pressure test first Then check the electric cooling fan operation or fan clutch if you have one.
Also make sure you have bled the cooling system and there are no air bubbles in the system. Turn on the heater so the heater core fills with coolant just to make sure there are no air pockets in the system.
Thank you for your prompt reply. No wonder so many people ask for your help! I actually fixed the problem last night. It was definitely air in the system. I had to reposition the thermostat with the jiggler valve up (should have read that in the shop manual!) and manually burp the system by squeezing the lower hose to get the air out of the block. Drove it around for over 20 miles of mixed driving, and even having to stop for the world’s longest freight train and it now sits dead center on the gauge.