Overheating problem

[Flicktitty]

Car: 1993 Nissan 240SX Coupe Auto.

Car over heated about a week ago, And i told Liz to bring the car down we then brought the car to my buddies place to put a new thermostat in it. Well that DIDN'T solve the problem.

So i put in the a new radiator and dual electric fans that i got for when i do the swap. I wired the fans to the stock harness (to turn on when the stockers do) I also filled it up with 50/50 mix coolant. (NO WATER, the car was runnning mostly water before) Turn the car on and let it run for a while (30min) then it started over heating again! WTF! so i checked for any leaks and i fixed the one hose that had a slight leak. Checked it again and the car was fine. I left the car like that then tonight i was driving it home and noticed it started overheating again.

What do you think the problem is? Coolant temp sensor? Something wrong with when the fan turns on? Headgasket? what?

When i put the heat on full blast the car cools right back down, Then once i turn the heat off it stays fine for a while then slowly starts to climb again.

Any thoughts?


Cliffnotes: OVERHEATING KA24DE, NEW THERMOSTAT,RADIATOR,DUAL E-FANS,NO VISUAL LEAKS,NEW COOLANT OVERFLOW TANK, STILL OVER HEATS.

[Reverend Cooper]

well if the heater is on its acting as another radiator and fan,that tells me there is either a coolant flow issue and or a air flow issue. have you checked to make sure that the lower hose is not collapsing and sucking closed? other wise i almost would rule out the headgasket as the air pocket would usually go to the highest part of the coolant system the heater core,tuning the fan on hot air in the core will not cool it down. plus if it was a headgasket it it eventually would push the coolant out the overflow. get a infra red thermometer and let the car run at idle make sure the fans are turning on at the correct coolant temp. if yes that operation should be fine if no maybe the temp swith for the fans is a issue. when moving the fans really dont need to run much,but when moving coolant flow is a must a lower hose sucking shut is a easily and very oftem a overlooked item

[Flicktitty]

well if the heater is on its acting as another radiator and fan,that tells me there is either a coolant flow issue and or a air flow issue. have you checked to make sure that the lower hose is not collapsing and sucking closed? other wise i almost would rule out the headgasket as the air pocket would usually go to the highest part of the coolant system the heater core,tuning the fan on hot air in the core will not cool it down. plus if it was a headgasket it it eventually would push the coolant out the overflow. get a infra red thermometer and let the car run at idle make sure the fans are turning on at the correct coolant temp. if yes that operation should be fine if no maybe the temp swith for the fans is a issue. when moving the fans really dont need to run much,but when moving coolant flow is a must a lower hose sucking shut is a easily and very oftem a overlooked item


It's not the hose's those are all in good shape and not collapsed. The fans do turn on, they take a while to kick on but they do work. at idle or when moving. I'll look again at the lower hose though. even when the car is moving it gets hot.

[Reverend Cooper]

if the lower hose collapses under suction from the water pump when moving it restricts flow thus overheating,is the cool coolant cant get outta the radiator via a collapsed lower hose then it starts to run hot,thus circulation thrw the heater core with the fan on will help cool it down. again just suggestions i would have to see the car

[Flicktitty]

Thanks coop, i'll give that a try tomarrow morning.

[Reverend Cooper]

also make sure that you burped all the air outta the coolant system, jack the front end up,radiator cap off and heater on do that first before going any further nic

[wrath]

After you start it up, how long until the upper radiator hose gets hot? I'm leaning towards air in the system > jank thermostat > collapsed hose

The heater core, if like most american cars, bypasses the thermostat and the radiator. Plus, it doesn't have an air problem due to its location.

[Flicktitty]

After you start it up, how long until the upper radiator hose gets hot? I'm leaning towards air in the system > jank thermostat > collapsed hose

The heater core, if like most american cars, bypasses the thermostat and the radiator. Plus, it doesn't have an air problem due to its location.

it takes a bit like 8-10min? i'm not real sure though. And it has a new thermostat in it. i'll look into this stuff tomarrow.

Me and a buddy bleed the system a few times but we are gonna re try it.

[LIZMO]

i hope it gets fixed. :-/

thanks guys for the input.

[theavenger333]

usually air in the system would cause it to fluxuate wildly though? this sounds like its just not flowing right. bad hose sounds pretty accurate, otherwise internal. when did it start happening? also, is it just the temp gauge telling you its overheating? sounds silly, but when the temp sensor goes bad, it'll say its overheating but the motor is fine. if burping it really good doesn't work, usually Coolant sensors are not that expensive.

[Flicktitty]

usually air in the system would cause it to fluxuate wildly though? this sounds like its just not flowing right. bad hose sounds pretty accurate, otherwise internal. when did it start happening? also, is it just the temp gauge telling you its overheating? sounds silly, but when the temp sensor goes bad, it'll say its overheating but the motor is fine. if burping it really good doesn't work, usually Coolant sensors are not that expensive.

i believe it started Thursday night or friday night. I'm gonna take it to a 240 guy tonight and see what he thinks, and tomarrow we are gonna try a few more things, maybe the sensor is bad, but i hope not cause i doubt there is one in stock in this area.

[LIZMO]

it started about a month ago, i was taking my last two deliveries for the night, and i noticed the motor being alot louder than normal, looked @ the temp gauge and it was over heating, turned car off for like 5 mins, turned it back on and it was fine... up until friday it did the same thing again, then i just drove to work @ at work with the heat up and then told my work i had to stop driving it. drove it out to nicks house, (was fine the whole 35 min drive on the freeway to nicks with the heat on 2)

[Sprayaway Fox]

small cars are time consuming to burp out the air bubbles. If you think its a head gasket, look for a greenish tint on the plugs. I had in my dakota with similar issue.

[Reverend Cooper]

that funny noise your heard,did it sound like marbles rolling around in a coffee can? Ping type noise, if so it was overheating to the point of detonation,so what may have been an issue with the t-stat may now be a issue with the headgasket

[LIZMO]

problem is fixed, the "new" thermostat ended up being junk.

[Reverend Cooper]

cool

[theavenger333]

thats good, much easier then messing around with god knows what else!

[Sprayaway Fox]

AZ thermostat? allota times the spring gets cocked and will stick or stay closed. That was my issue wit da dakota. Good to here

[LIZMO]

nope the thermostat was from Napa, Actually the new thermostat is from AZ.

[Sprayaway Fox]

I only seen it a handful of times so prolly no worries.:thumbsup A lotta places sometimes get there stuff from the same wholesalers anywayz, no matta where you go. good to here you fixed it though:thumbsup

[LIZMO]

im glad its fixed too! since i only got a couple months to drive it till next year