Overheating

[phuoc_dat]

Can somoene diagnose this syptom for me? My car overheat every 5-7 minutes of driving. The arrow would hit H and i could only drive under 3 rpm. I recently flush my coolant and i know for a fact i had put in enough ccoolant in the radiator. The coolant is not leaking but my car still overheating.
By the way i drive a 93 240sx

[NAIZBST]

you might have an air pocket , I would try to put the car on an incline and let it warm up with the radiator cap off and see how many air bubbles come out of the radiator cap.but you need to make sure you keep the radiator higher than any other component on your cooling system(thats why it needs to be on an incline)

[phuoc_dat]

how would i fix the air pocket problem? YOu dont think its the thermostats problem?

[NAIZBST]

it could be a thermostat problem too, but I would try bleeding the air from the system and also checking to see if the thermostat is opening and closing and not stuck closed.

[Wurm]

try cleaning your coolant sensor or replacing it. IS your fan coming on? Check your waterpump?

[3kgtdrvr]

did it just start overheating after u flushed ur cooling system? if so u probably have air in it. i dunno about 240s but there might be bleeder screws on ur car for the coolant. id say do that and check out the thermostat first. also if u just put a new thermostat in and it has a little hole with a dangly thing in it, make sure its facing up. it could be other stuff too but id probably check that stuff first and then move on from there.

[phuoc_dat]

my car was driving fine until yetsterday after i took my bro to work. When i got near home my car started to make a weird noise coming out from the engine. Then i found out my coolant was leaking through the radiato drain plug. I den tighten the drain plug and it broke so all my coolant water drain out. I then found a substitute plug to plug up the hole and add some new coolant on it. From that on, my car keep hitting H whenever drive for 6- 7 minutes.

[phuoc_dat]

i havnet bought a thermostat yet, not sure what the problem is. Is installing a thermostat hard?

[Wurm]

i havnet bought a thermostat yet, not sure what the problem is. Is installing a thermostat hard?

no takes like 10 minutes... Follow your upper radiator hose to your water inlet. Remove water inlet and install new thermostat and gasket. Reassemble

[phuoc_dat]

so everyone thinks its the thermostats? because im pretty sure the waterpump is working since i can feel the tightness of the radiator hose when i press it. Do i have to drain the coolant in order to install the thermostats?

[Wurm]

it could be a dirty coolant sensor those are prone to go bad on 240's. The coolant sensor is right under the burb screw which is next to the water inlet

[3kgtdrvr]

yes u have to drain the coolant to change the thermostat. well, unless u wanna get really messy lol in general the thermostat is working is the lower and upper radiator hoses are about the same temp with the engine running, not saying it couldnt be bad, but its just a tell tale sign that it could be a thermostat, or air in the system, or blockage, or all sorts of stuff...so i guess that wasnt much help then lol

[phuoc_dat]

nah just found out its not no air pocket. Im going to replace the thermostats in a couple of days

[NAIZBST]

thats cool

[Wurm]

coolant sensor dont forgot to replace that

[phuoc_dat]

so ur saying if the sensor is bad, its giving me wrong signal on the temperature gauge. N if its giving me wrong signal on the gauge does it really mean my car is overheating?

[Wurm]

yep and they are prone to goign bad on 240's

[AE86 Dorifto]

Is it an sr20? If so, they overheat easily. Is it an aftermarket radiator? If it's sr20, you need one. Also, consider a hood-lift. The difference when you get a hood-lift is amazing.

[phuoc_dat]

yea aftermarket radiator but not an sr20

[AE86 Dorifto]

Is/are the fan/fans working? Is/are it/they aftermarket? Does your car kinda smell like pancakes when you you drive it or open the hood when it's hot (serious question)? If it smells like pancakes, you need a new radiator cap.

[Wurm]

I get a hint of blueberry pancake J/k

[phuoc_dat]

nah doesnt smell like pancake. The gauge just hit H after i drive it around for 5 - 7 minute reving to around 3-4 rpm. changing thermostats tomorrow, hoping it will work. If thermostat doesnt fix the problem, does that mean the head gasket is mess up?

[phuoc_dat]

Does head gasket have anything to do with overheating if so how much to fix. An estimation.

[3kgtdrvr]

yes it could...and u dont wanna know how much lol if u blew ur headgasket u might wanna just go ahead and look into doing an sr20 swap. it means pulling the head off the block, checking to see if the head or block it warped and if so, some machine work, possibly O2 sensors bc coolant kills them...who knows what else u might need

[3kgtdrvr]

in general, if u take off the oil cap and its not all foamy and milkshake-like underneath it, ur headgasket should be ok. the coolant is gonna force its way into the oil bc its under high pressure. thats just in general though, it could still be bad. if its not all foamy underneath it then id go ahead with the thermostat and the temp sensor, since its apparently is prone to go bad. thats just my :2cents: though. i dont wanna get blamed if ur engine blows lol

[~The_Duke~]

I bet it is the thermostat or temp sensor also...:2cents:

[phuoc_dat]

if temp sensor is messed up, den the temp gauge will still work right? As of right now the temp gauge does work and not sure if the sensor is messed up. Where is the sensor located? Any visual pix u can upload?

[3kgtdrvr]

sometimes depending on the car there will be two engine coolant temperature sensors...one going to the computer and one only for the dash. it can still work and be wrong, u may not even be running hot. its probably somewhere where the coolant hoses go to the engine. i dont have any pics but itll be like a little sensor lookin thing screwed into the metal with wires going to it

[phuoc_dat]

well i change the thermostat but it still get to the H when driving with high rpm. When a car hit H, does it mean smoke has to come out or u have to be on H for quite a while. Hopefully the problem is not the head gasket since u said it cost alot to fix it. so which coolant temperature sensors do i need to replace? one going to comp or one going to dash? Do you think they sell the temp at napa, autozone, or pep boy?

[3kgtdrvr]

the one that is bad, duh lol u might only have one, i dont know 240s. i dont know what ur talking about when ur saying smoking...when ur car starts smoking its not good lol it shouldnt really get much higher than the middle mark. if u ran it too hot u could have blown the head gasket, let alone fucked all other sorts of stuff up too...ur engine could be totally wasted.