supra is still overheating!! im stumped!!!!

[#1StunnaVic]

ok so i changed the thermostat, flushed out the entire cooling system until i saw clean fresh water coming out. i jacked the front end of the car up with the heat on full blast (which was real warm by the way after changing my heater core) and purged the system. i got a thermostat for a 98 supra which is a 180 degree thermo.
im pretty sure i got all the air out i let it purge for like 15 minutes. i revved up the motor to so the water pump could move the coolant and possibly any other air that might not have got out at idle. i thought i has solved the problem because the temp gauge was at little below half for awhile. then it crept up to half and stayed there for awhile, then slowly but surely it was making its way up to 3/4's. it was just under the 3/4's mark. and it seemed to b stayin there but im not sure because i didnt let ut run too much longer after i saw it going up. i used a infared thermometer and aimed it on the upper water neck and various other places where coolant lines run. (i got as close to the thermostat housing as i could but i still think i could got closer.) the highest reading i got was less than 160. i think maybe the infared isnt working as well as i thought it would so im gonna try putting an actually thermometer into the radiator and see if i can get a better reading.

If the readings are still fairly close with the thermometer in the rad as it was with the infared then im starting to wonder whether the resistance in my gauge is no good. i had the cluster all apart when i put the 1j tach in it but i was sure not to drop it or anything like that. could it b possible that i may have messed it up when i took it apart (i dropped the temp gauge out of the cluster from my old legend and when i put in back in it always read hot). i have an aftermarket mechanical autometer water temp gauge that i wanna put in there but unlike the 7m im not sure there is a place where i can put it. does anyone have any suggestions for that?
I need some serious help here guys im stumped. should i try running it without a thermostat? should i just drive it as see what happens?

 

[SPD TRP]

ok so i changed the thermostat, flushed out the entire cooling system until i saw clean fresh water coming out. i jacked the front end of the car up with the heat on full blast (which was real warm by the way after changing my heater core) and purged the system. i got a thermostat for a 98 supra which is a 180 degree thermo.
im pretty sure i got all the air out i let it purge for like 15 minutes. i revved up the motor to so the water pump could move the coolant and possibly any other air that might not have got out at idle. i thought i has solved the problem because the temp gauge was at little below half for awhile. then it crept up to half and stayed there for awhile, then slowly but surely it was making its way up to 3/4's. it was just under the 3/4's mark. and it seemed to b stayin there but im not sure because i didnt let ut run too much longer after i saw it going up. i used a infared thermometer and aimed it on the upper water neck and various other places where coolant lines run. (i got as close to the thermostat housing as i could but i still think i could got closer.) the highest reading i got was less than 160. i think maybe the infared isnt working as well as i thought it would so im gonna try putting an actually thermometer into the radiator and see if i can get a better reading.

If the readings are still fairly close with the thermometer in the rad as it was with the infared then im starting to wonder whether the resistance in my gauge is no good. i had the cluster all apart when i put the 1j tach in it but i was sure not to drop it or anything like that. could it b possible that i may have messed it up when i took it apart (i dropped the temp gauge out of the cluster from my old legend and when i put in back in it always read hot). i have an aftermarket mechanical autometer water temp gauge that i wanna put in there but unlike the 7m im not sure there is a place where i can put it. does anyone have any suggestions for that?
I need some serious help here guys im stumped. should i try running it without a thermostat? should i just drive it as see what happens?

Sounds to me that maybe the gauge may be out of whack. If the infrared says you are in the ballpark but the gauge does not, its one or the other.

Do you have a buddy that you can compare infrared reading with, maybe side by side. Are you having any coolant dislocation from reservior, or any other overheating syptoms?

Just kinda a stab in the dark.

Wayne

 

[Spaniard]

If it was over heating the coolant over-flow would boil.

 

[thechori]

If it was over heating the coolant over-flow would boil.

QFT. when my car was overheating the coolant was boiling like a mofo, and there was steam coming from somewhere near the firewall (exhaust side)

just a little from my experience

 

[tlo86]

use a diff gauge to mon it that sensor might be no good no mo!

 

[LilMissMkIII]

This may be random, but i just popped on a giant tranny cooler at the weekend, and my heating issues are 99% better now...

 

[tlo86]

is his automatic? the coolers definitally help if its the case i used one and im going to use it again for my p/s.

what fan are you using?

 

[93kyumaru]

I have had this same problem in a 1JZ JZA70 MKIII here in japan, I did all the same things you did flush the rad core, heater core, new thermostat it had nice factory clutch fan, but after all that trouble turned out that the wire on my sensor (Little Gray sensor in the water neck) had oxidation and corrosion inside the plug so it was giving a false reading of overheating all the time. Just another thought swap that sensor with another car that has that same style sensor try it out might be your answer other than the water jackets in your block being full of gunk that just won't flush out and constricting the amount of coolant that can flow through the block and cool it off (had that happen too)

 

[JASONA70]

is yours a hydraulic fan or a clutch fan? if its hydraulic fan then make sure the fan ecu is plugged in. the sensor for that should be at the bottom of the drivers side rad.

 

[#1StunnaVic]

hydralic fans,yea the fan sensor is plugged it (one at the driverside bottom corner of the rad) the ecu for the fans is plugged in (checked twice). that sensor in the water neck might just b the problem. because the overflow tank has no coolant in it and the coolant wasnt boiling over. no steam or anything like that. my car is a 5 speed r154 by the way. there arent really any signs of overheating besides the temp gauge. im gonna try and hook up the autometer gauge that i have 2morrow and see what happens...

after all that trouble turned out that the wire on my sensor (Little Gray sensor in the water neck) had oxidation and corrosion inside the plug so it was giving a false reading of overheating all the time. Just another thought swap that sensor with another car that has that same style sensor try it out might be your answer other than the water jackets in your block being full of gunk that just won't flush out and constricting the amount of coolant that can flow through the block and cool it off (had that happen too)

what kind of car carries the same sensor that the 1j uses to give the temp readings?

 

[93kyumaru]

The Celica Sensor is probably the same resistance or close enough or just another 1JZ/2JZ sensor what I did is just by pass the coolant temp sensor in most apps I drilled and tapped the hole to suit a defi Sensor.

 

[#1StunnaVic]

where exactly is the sensor located at in the water neck? and just to be clear when u say water neck do u mean where the upper radiator hose goes into?

 

[93kyumaru]

This is a 1JZ right? if it is then yes the upper rad hose water neck at the base of that neck (on a 1JZ) there are two sensors (Top) Gray one is the water temp sensor the (Bottom) Green one is cold start. I would pull the harness off get some contact spay and canned air blast it out hit it with the contact cleaner and if you have a wire brush spin it around in the connector to remove any remaining debris.

 

[The Reaper]

definitely a faulty gauge/ dirty connector.

if you open the rad. cap and start the car and once its at OT you see water flowing thru the radiator then that means the tstat is working and if its flowing there's no way its overheating. definitely the sensor/wiring/or gauge

good luck

 

[#1StunnaVic]

thanks guys ill take a look at the sensor today when i get a chance. and yea i ment where the sensor is located on the 1jz. this puts me at great ease guys i apprciate it.
ill keep you updated!