overheat troubleshooting

[BlackieCG6]

so my car overheated over the weekend 1st time it happens. The radiator
was bone dry, anti-freeze was drippin on the engine cover below. the reservoir was full though. so I started trouble shooting poured anti-freeze into the radiator to find the leak, result no leak. left car on for about 20 minutes temperature was regular but fans wouldnt turn on except with the AC on.
I changed the water pump, hoses & thermostat less then year ago all oem parts except the hoses. changed the fan relays still nothing so i've been running the car locally with AC on so fans can work. only thing left is to change temperature sensor that goes ontop of t-stat. is there anything i forgot to check ? or any suggestions ?

 

[HondaLuver83]

Is there a sensor on the radiator itself? if so, replace that one first. On most cars, its the sensor that activates the fans.

 

[BlackieCG6]

to be honest i didnt see one on the diagram or my car & the dealer didnt mention that either im gonna check again tho

 

[FunnyVictor86]

here is the radiator assembly ... doesn't seem to have a sensor

http://www.hondaautomotiveparts.com/auto/jsp/mws/prddisplay.jsp?inputstate=5&catcgry1=ACCORD&catcgry2=1999&catcgry3=4DR+LX&catcgry4=KA4AT&catcgry5=RADIATOR

there is one where mentioned, on the T-stat housing ... there are more sensors on the diagram but unfortunately i do not know what they do lol

http://www.hondaautomotiveparts.com/auto/jsp/mws/prddisplay.jsp?inputstate=5&catcgry1=ACCORD&catcgry2=1999&catcgry3=4DR+LX&catcgry4=KA4AT&catcgry5=WATER+PUMP+-+SENSOR

 

[finch13]

I believe the fans are controlled solely by the ECT in the cylinder head. Even so, the fans only cool when you're idling, they almost never operate while driving.

In order to actually find the leak you'll need to fill up the system and do a pressure test on it. Parts stores like O'Reilly and AutoZone may rent the tool...

Basically, fill and bleed the system. Attach the pressure tester to the radiator filler neck and pump it up to 15 PSI. Watch the pressure, it should not drop very fast... and hold 15 psi for a few minutes. This will also force coolant out of wherever the leak is and it won't evaporate right away because the engine is cold.

Areas to check:
- Water pump - coolant leaking out of lower timing cover
- Thermostat housing - follow lower hose
- Upper radiator hose adapter - front of cyl. head
- Water pipe - back of block, under intake manifold, check underneath car
- Bypass hose/intake manifold hoses - back/underside of intake mani
- Heater hoses/heater core - hoses going through firewall... heater cores usually burst when they go... and youd smell it
- Radiator - check seams between aluminum and plastic
- Headgasket - after pressure test, white, maple syrup smelling smoke is bad. Coolant in the oil is bad, oil in coolant is bad, etc.

 

[BlackieCG6]

wow u guys r thorough, well i've already ordered the sensor on the t-stat which u see on the diagram and the ECT sensor hopefully i'll pick em up saturday morning.
only thing off that list not checked is bypass hoses and the intake mani.... no white smoke & the car was idling for about 20 minutes and no fan, i ran the car near by and then let it idle again still no fans. i dont see anti freeze leaking anywhere and ever since i filled the rad again its all there.

well i thank you guys for all your knowledgeable info thats why i come here

 

[f23accord2000]

i had some what of the same problem, i was over heating all the time, after the 4th (aftermarket) thermostat still overheating i went to honda an bought a OEM thermostat and a fan switch that is on top of the housing that goes into the thermostat (4cyl)not sure about the 6, word of advice dont buy aftermarket thermostats for our cars they dont work properly.

 

[BlackieCG6]

all fixed, changed the switch on the T-stat for the hell of it guess. The problem was the ECT (coolant temperature sensor) which is # 17 on the diagram, installed let the car warm up and "viola" the fans were alive again. Thanks once again guys for all ur info

 

[HondaLuver83]

all fixed, changed the switch on the T-stat for the hell of it guess. The problem was the ECT (coolant temperature sensor) which is # 17 on the diagram, installed let the car warm up and "viola" the fans were alive again. Thanks once again guys for all ur info

Nice, what was wrong with the old switch? You got a lot of miles or the coolant corroded the surface of the sensor.

 

[BlackieCG6]

i ordered that thinking that was the rite part, so i changed it anyway it look corroded though oh well