so I am getting ready for FI everything is at the house waiting to be installed. I decided to install the koyo before just to have it out of the way. I install it. fill it up let it idle... everything is fine... start driving and it starts to overheat. I pull into a gas station and thought that there was an air pocket. Open the bleeder valve(on the heater hose running back to the firewall) lets out a big whoosh and the overflow tank(that somehow got full to the brim) goes almost empty about right where it should be actually, so I think there I got rid of the air pocket everything is fine. NOPE cant drive more than a couple of blocks without having to wait 5min for it cool down. a few odd things ot point out.

1. the heater on full blast will NOT blow any hot air whatsoever.

2. I checked the bleeder valve again and there was not any air only really hot water.

3. when the fans come on they are really loud. I guess it is full blast not just auxillary

4. I open the radiator cap and it really gargles a lot, not normal from what I have seen, but I have never done it with a 350z

5. the upper radiator hose gets hot, but the lower one is regular temp.

6. overflow tank filled up. then when I let the airpocket out it emptied. When I ran it again it started to fill again.

the only thing that I can think of would be somehow the thermostat is not opening, but I still wouldnt understand why?

any help is greatly apreciated!!

 

#1 thermostat not opening, #2 sounds like you still have air in the lines

 

https://my350z.com/forum/showthread....hlight=coolant
Try this

 

Bad Thermostat / installed backwards ??? Just an idea ....

 

Thank you istan...always helping me out. I will try that in the morning and get back to you with(hopefully) the good news!

 

Never touched the thermostat only radiator. thanks though

 

Btw, make sure you're not leaking anywhere.

 

+1

 

+2 on the thermostat,

take it out completly and see if you get normal temps and some heater after the car is warm.

 

i have no idea why it would be the thermostat though. It worked fine before it swapped out the radiator. and i never touched it. I let the car sit outside and idle for like 15 min while i cleaned up, pulled foward and there were no leaks. why wouldnt the thermostat open once I put in the koyo?

 

Sometimes they just go bad. Overheated by the conditions. Contamination. It's a cheap part and easy to check. Worth the time imo.

 

I wouldn't be the first to say it's your thermostat in this case, but considering they're pretty easy to test, it wouldn't hurt to throw it in some hot water to see if it opens.

 

The Z Thermostats arent cheap ---they are intergraded as part of the hose inlet---also explaining why they cant be put in backwards. They go bad, true------But if as you say the top hose is heating up, that means its opening.

The bottom hose WILL be cooler because it is reintroducing "Cooled" water back into the motor, whereas the top hose (with the therm open) is introducing "Hot" water from the engine into the Radiator.

When you start the motor, the top hose will remain cool until the water hits 190 or so, opens the thermostat and starts water circulating.

Keep bleeding it with the heater on ----let it sit over night and let the air find the high spots

 

I let it sit overnight and all day today. right now I am bleeding it slowy. I am letting it run for a couple of minutes and then opening the bleeder screw, and it lets out a little pssht of air then water comes out. I have done it three times and now I am letting it cool. I tried to open the rad cap the first time because i thought that The bleeder left all the pressure out. I was wrong. So im going to try this out and see if it works...

hopefully!

 

its getting better!!! will post when back to normal. I can drive around for as long as I want but the fans still kick on hard and loud, plus the heater goes hot then cold.

THANK YOU MY350Z members!

 

air bubbles in coolant biggest problem these cars have after doing any coolant changes.

 

Sounds like ya just need to keep burping it.

Like others have said keep the engine running and bleed the air out of the highest point in cooling system.

I always keep a hose on by me so i can add a little water as i burp the engine.

This may take several times, enough times maybe to where you start saying wtf. At this point your almost there.

Once temp seems ok at idle go drive it around a few minutes and come back and bleed any air out again. Even if everything seems ok do it anyway to be sure.

 

When you refill the colling system try filling it first at the heater hoses or somewhere behind the thermostat. This is a common problem with many cars upon refilling.