first assumption...
-cracked radiator...

2nd assumption
-faulty thermostat
(ran cold with radiator cap OFF, once car heated up fluid disappeared and cycled so im pretty sure this isnt the issue)





issues....
-minor leaking from radiator side (given)
-over heating at lights
-fluctuating rpm's at idol



just seeking some thoughts on the issue and willing to entertain any suggestions....



thanks in advance

 

You should be able to see a leak. Coolant on the ground. Decrease coolant level in reservoir. That will confirm or eliminate one potential source.

 

Did you add coolant recently? Search air bubble. Z is notorious for air bubble.

 

Check:

1. Used oil analysis. (head gasket)
2. Air in the cooling system.

 

i had issues once with idling but it ended up being o2 sensor had to check voltage to them, make sure the heater circuits were kickin on, may have to replace a upstream sensor. check all clamps on all hoses, i hate the nissan clips i use the standard flat head screw clips instead of oem squeeze type. i use to leak from lower rad hose, and at the thermostat til i made the change, i am running all silicone hoses as well. maybe its the thermostat, i remember using a laser thermometer and the z takes awhile even with a mishimoto thermostat to open the gate i think it was like 9minutes. again note this a tuned car. air bubbles is definetly another factor! i dont use the relief valve, i jack the front up so the rad cap is the highest point.. and run the car full blast heat til all the bubbles come up.

 

coolant levels in reservoir were depleted... i added more the next day and after some minor driving in the morning, it was empty again...

there was some coolant on the ground when i got home, i noticed it....
I noticed steaming coming from my radiator after trying to angle a huge driveway and after needing to lift my e brake and throw it in reverse.... once i parked the car was steaming and i smelled coolant and noticed through my vented hood that the radiator was leaking steam.



_______________

recent street assessment ...

i drove down the street, around the mall area, a lot of stop and go and the car started to heat up (near the H mark)... took the car to my dads (he is pretty knowledgeable with mechanics) and turned the car off, went inside for about 5 mins, discussed the issue.... he wanted me to go back outside and re-simulate the issue... i didnt think it was a good idea seeing as how i didnt want to cause any issues with the head gasket... but he wanted to locate the area where the steam would be coming out if indeed it was a radiator leak....

so i drove it pretty hard (damn near raced it) on the side streets near my house for a good 2 mins, went back to his house and there were NO ISSUES what so ever... no heating issues, no fluctuating RPM band... heating levels were a little lower then 1/2 way...

blows my mind... im ready to just toss a new radiator at the car but in my experience, its never a good idea to just throw parts at the car without properly diagnosing the issue FIRST



with all that said... ideas??

 

air in the cooling system... makes perfect sense!!!

i was on that huge driveway (nose down) and after having to cause a jump in the RPM's to back up then the car started to "over heat"....

how do i get the air out of the lines!!!?!??!?!

 

^^
Up

 

Year/miles? Have you ever done any cooling maintenance before? In my experience it's 9/10 the thermostat. Tricky little things, sometimes they stick sometimes they don't, depends on the type you have in there. Personally I would just change the thermostat and flush the system and put new coolant in.

 

Make sure you track the issue down before its too late. I just had my radiator explode in the highway out of no where. It started to get hot and it just went boom. I have the car now ready for a new radiator, water pump and thermostat. GL...

 

I would replace the radiator and thermostat.

One way is to open the air valve behind the plenum to rid of air bubbles. Or do as i did I unplug the two hoses. (Top and thermostat hose) Poured in coolant and reinstall them and start the car. Squeeze the hose to push the coolant through.

 

As I mentioned only two ways to deplete coolant:

1. External leak
2. Burning coolant in the combustion chamber.

Coolant leaves a oily residue. A good mechanic may be able to trace the residue and identify the source of the leak.

 

Im having the same issue new thermostat new mishimoto hoses new waterpump new radiatornew coolant sometimes it over heats sometimes it doesn't I found the leaking is from the weeping hole on riverside due to pressure from getting hot and tstat not opening im thinking air bubbles cause sometimes it opens sometimes the tstat stays closed its really getting stressful.

 

-Use some periods. Spell check also helps. I have no idea what a weeping hole on riverside is...
-This thread is almost a month old. Start your own.
-Bleed your coolant system.

 

Locate you leak.
fix the leaking issue.
bleed the car.

If that doesn't fix the issue, check thermostat...

Pretty sure the leak caused air to get in the system.
air in system leads to hot spots and steaming....

Flucuating idle is most likely from this issue