Hi i bought 2002 nissan sentra ..previous owner replaced head gasket ,water pump.thermostat ...car was running good for a week then sudeny no hot air inside(blows but cold) and 10 minutes later overheated ...coolant lvl looks fine but lower hose is cold ...when i squeeze it for 10 minutes it will get warm and i get heat and car will drive fine no overheating ...now sometimes will start rough ....doesnt appear to mix coolant and oil ... any ideas?/ ty

You may want to check and see if the ECT (Engine Coolant Sensor) is faulty. It should drive the temperature gauge and if it's bad, it could be telling you that the engine is overheating when it is actually running at normal temprature.

You have a leaking engine cylinder head gasket, this may be due to the previous overheat or a result of it, make sure when you have the engine repaired you find out if the cooling system is in good condition or the problem will recur.

have a local mechanic do a pressure test on the cooling system as i think that a vehicle this old could need a new head gasket as they do deteriorate with age especialy on vehicles around the 98 to 2002 era with that funny bonding material that was used

A clogged catalytic converter or a restricted exhaust will cause over heating. Also a cracked head or bad gasket. Also, if your engine timing is very far off it will overheat. Make sure you have all the air out of your cooling system and it is actually running hot, not just your gauge showing it's hot.
I hope this helps.

seems like you might have a bad head gasket remove radiator cap and let it run. make sure the antifreeze is flowing if not it could be the water pump prop many car makers are using plastic props and they fail with time.also very possible that thermostat is bad was it overheating before it received a radiator ,cap and thermostat if so it is between head gasket.,and water pump but if you have no flow it is possible that the water pump prop is broken .there is head gasket test that can be done most shops have them and cost a little to do.to be sure.

Not generally, unless the engine's been run hot, if even only for a moment. If the head gasket is blown prepare for major out of pocket expenses because if the engine overheated it will bend every valve and usually warp the head beyond repair. I honestly hope this is not your problem, it's an extremely expensive fix. Hope this helps, good luck!

check for a blown head gasket it will sometimes pump air into the heads and make the coolant levels seem fine but in truth they are not and check the water pump for rusted fins make shure the water level sucks down during sharp throtteling of the motor if so the cooling system is fine as far as that goes but where to start

1.) tempature switch located on the motor it tells the ecu when to kick on the cooling fan

2.) fans spin freely without taking force

3.) thermostat it could be stuck closed due to someone at sometime only running water without antifreez and causing the pressure pin to rust and freeze the gate shut

4.) monitor the water levels if they go down suddenly as 1 gallon of water a week or 2 weeks its a bad head gasket you can see this on spark plugs as well

and for most your water pump make shure you get good heat from the heater at low running tempatures and start the car and monitor what the water in the radiator does (while its cold) the water in a car is over 195% and can easily do harm if the car is just warmed up not even close to over heating so you can imagine what it could do at an over heated state



but get the problem fixed or else you can result in blown head gaskets water in the oil piston breakdown do to rust in the piston walls and even worse complete engine failure

If all of the things you replaced are working fine I am going to say double check the thermostat. Also make sure your fan is engaging at temp. You cam check by running till warm and then running the AC. If the car does not overheat with the AC on then your fan is not running under normal conditions (with AC off) This can be caused by a couple of different things depending on how the fan is set up. I am not a nissan expert

A Blown head Gasket will cause the Symtoms described above. Check your Water Pump and Thermostat also.

My 2005 Nissan Sentra 1.8s with 55,000 mi. blows cold air from the heater. Coolant not circulating in engine. Lower hose stays cool to touch. Both heater hoses cold. Changed thermostat - didn't fix it. Coolant not leaking or dirty. None in oil - no oil in radiator. Changed worn water pump belt - pump spins freely with no noise or resistance. Cooling fans come on after warm-up. Temperature gauge stays in normal range then jumps to hot and back again. Coolant good to 10 below - didn't freeze here yet. No other problems or repairs to car. Afraid to drive and make worse. Help!