oh no.. overheating - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

kerv · 08-24-2002, 05:48 PM

89 240sx 98k miles KA

Here is the story:  I was driving home today about a 45minute trip going 70mph.  I had the AC on and the radio turned way up.  Passing cars as I go... then I glance at my Temp guage.  It is almost at the top!  I immediately turn off the AC and go into the slow lane and then I notice the guage is going down slowly.  So I thought, well I only have 5 minutes till my house... I can make it.  Glancing again at the temp guage and it is back to normal midway temperature.  I was thinking this was good... I just opened the windows and got the rest of the way down.

Once home, I open my hood to let it cool down somemore and my coolant lvl is way past MAX!  In fact it is almost over flowing.  I can hear it boiling or some type of bubbling noise and the line that leads to the tank is piping hot.

Can anyone tell me if this is bad, what the problem could be, or what I should look out for when driving some more?  I don't normally have the AC on... but sometimes I do.  How could this relate to overheating?

Thanks for your help
- Kevin

rampid360 · 08-24-2002, 06:36 PM

The cause was probably related to either your radiator cap or thermostat.  (since the tube that leads from the radiator TO the engine was boiling hot...its probably thermostat)

You probably should replace both...because every now and then they do need to be changed out.  

Then again, theres a very good chance that it just stuck for a moment, and will NEVER happen again. (this happened to my late 240..overheated once, never again)

-Al

Itsuki · 08-24-2002, 10:19 PM

I just had that same problem, i replaced my thermostat cuase it was bad and my radiator cap was also bad, and then just to be safe i went ahead and replaced my upper and lower radiator hoses, and flushed out the cooling system with some cleaner stuff my dad bought from Kragen, and then replaced it with new coolant it runs cooler now than it did when i bought it....

kermit80 · 11-21-2002, 09:47 AM

I think it was something stuck in your radiator.  If it was your thermostat....it may be your thermostat...but usually your thermostat would stay stuck...and your temp would stay HOT....it would reject waterflow...the radiator cap is good to change if you have had it for a long time...because it could seep air into the system which causes your coolant to lose pressure and boil faster..anytime you have a leak in the system..your boiling point of the coolant goes down allot....you could try getting away with just changing the cap..and looking for any other leaks.  I just had a really small one recently on the upper hose.  If you want to not deal with it anymore...change the thermostat as well.....and first take it out...put the hose back on..and flush the system.....do that several times..before you put in the new thermostat.  Check the hoses if they are weak and easy to push in....cracked or bulging.....replace those hoses so you don't deal with them later.  Then you should be set!!!  I still gotta change my thermostat and flush the system...that will work wonders....

THX1138 · 11-21-2002, 09:01 PM

I had a similar situation last summer. My first thought was that it was the thermostat, so I changed it. What a pain, had to get underneath to reach the third bolt. Everything was fine for a week or so, then it did it again. <img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/mad.gif" border="0" valign="absmiddle" alt=':angry:'>

It turned out that my occasional overheating episodes were the death throes of the water pump, which had decided it was time to retire after 115K miles.

Hopefully your problem is just the thermostat, but be prepared for something a little more expensive...

08-24-2002, 05:48 PM	#1
kerv Leaky Injector Join Date: Jul 2001 Location: Canada Posts: 119 Trader Rating: (0) Feedback Score: 0 reviews	89 240sx 98k miles KA Here is the story:  I was driving home today about a 45minute trip going 70mph.  I had the AC on and the radio turned way up.  Passing cars as I go... then I glance at my Temp guage.  It is almost at the top!  I immediately turn off the AC and go into the slow lane and then I notice the guage is going down slowly.  So I thought, well I only have 5 minutes till my house... I can make it.  Glancing again at the temp guage and it is back to normal midway temperature.  I was thinking this was good... I just opened the windows and got the rest of the way down. Once home, I open my hood to let it cool down somemore and my coolant lvl is way past MAX!  In fact it is almost over flowing.  I can hear it boiling or some type of bubbling noise and the line that leads to the tank is piping hot. Can anyone tell me if this is bad, what the problem could be, or what I should look out for when driving some more?  I don't normally have the AC on... but sometimes I do.  How could this relate to overheating? Thanks for your help - Kevin __________________ Kerv 89 Nissan 240sx FB Alberta Canada

08-24-2002, 06:36 PM	#2
rampid360 Zilvia Junkie Join Date: Jan 2002 Posts: 328 Trader Rating: (0) Feedback Score: 0 reviews	The cause was probably related to either your radiator cap or thermostat.  (since the tube that leads from the radiator TO the engine was boiling hot...its probably thermostat) You probably should replace both...because every now and then they do need to be changed out.   Then again, theres a very good chance that it just stuck for a moment, and will NEVER happen again. (this happened to my late 240..overheated once, never again) -Al __________________ For every winner there are dozens of losers.  Odds are you're one of them.

08-24-2002, 10:19 PM	#3
Itsuki Zilvia Member Join Date: Jul 2002 Location: California Posts: 216 Trader Rating: (0) Feedback Score: 0 reviews	I just had that same problem, i replaced my thermostat cuase it was bad and my radiator cap was also bad, and then just to be safe i went ahead and replaced my upper and lower radiator hoses, and flushed out the cooling system with some cleaner stuff my dad bought from Kragen, and then replaced it with new coolant it runs cooler now than it did when i bought it.... __________________

11-21-2002, 09:47 AM	#4
kermit80 Join Date: Sep 2002 Location: Honolulu, HI Posts: 41 Trader Rating: (0) Feedback Score: 0 reviews	I think it was something stuck in your radiator.  If it was your thermostat....it may be your thermostat...but usually your thermostat would stay stuck...and your temp would stay HOT....it would reject waterflow...the radiator cap is good to change if you have had it for a long time...because it could seep air into the system which causes your coolant to lose pressure and boil faster..anytime you have a leak in the system..your boiling point of the coolant goes down allot....you could try getting away with just changing the cap..and looking for any other leaks.  I just had a really small one recently on the upper hose.  If you want to not deal with it anymore...change the thermostat as well.....and first take it out...put the hose back on..and flush the system.....do that several times..before you put in the new thermostat.  Check the hoses if they are weak and easy to push in....cracked or bulging.....replace those hoses so you don't deal with them later.  Then you should be set!!!  I still gotta change my thermostat and flush the system...that will work wonders.... __________________ 93 240sx...Sportline Springs, KYB AGX shocks, 3 1/2"exhaust, Whiteline Offset Rear bushings, 16" SSR rims, intake, spoiler, Momo steering wheel, Clarion DB625MP3 Deck....2nd 240sx...and waited 6 months looking for a good one with low miles.....wanted NOTHING ELSE....

11-21-2002, 09:01 PM	#5
THX1138 Zilvia Member Join Date: Sep 2002 Location: Clemson, SC Posts: 264 Trader Rating: (0) Feedback Score: 0 reviews	I had a similar situation last summer. My first thought was that it was the thermostat, so I changed it. What a pain, had to get underneath to reach the third bolt. Everything was fine for a week or so, then it did it again. <img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/mad.gif" border="0" valign="absmiddle" alt=':angry:'> It turned out that my occasional overheating episodes were the death throes of the water pump, which had decided it was time to retire after 115K miles. Hopefully your problem is just the thermostat, but be prepared for something a little more expensive...