*posting this everywhere to get some responses as fast as possible*

Hey guys. I just bought my first 350z and the guy I got it from says the valve gasket was messed up. I replaced the gasket correctly and it started running a lot smoother than before. I took it for a test drive and saw that when I pressed the gas pedal the thermostat would rise as I pressed it but went down when I let off the gas pedal to let the car coast. PLEASE HELP ME!

 

Ensure that you have the proper level of coolant.
Are you radiator fans turning on?
When was the last time the thermostat was replaced?

 

I haven’t been able to completely check the coolant level lately because it took me the weekend to do the valve cover gasket and such and I don’t get off work until the sun goes down. I was going to try and bleed the radiator this weekend. The guy I bought it from told me the radiator is brand new and so are the fans. I’m not sure he bled it to make sure no air bubbles are in it. My biggest concern is a blown head gasket.
edit: not sure when thermostat was replaced. Also there is no heat in the cabin.

 

How often has it been driven since the radiator was replaced? The cooling system in the Z is a pain to bleed. If the prior owner did a terrible bleed job and drove the car around with it overheating then yes, you may have reason to worry. Off the bat though I would check your coolant levels and fans just to be sure.

 

He took it to a horrible mechanic apparently. I’ll try to bleed it out when I get off today. I believe the thermostat is working because the hose towards the back does get warm but I haven’t check the front hose.
*EDIT* I believe he only drove it once before noticing it still over heated. The fans work and everything. I haven’t seen any leaks and the hoses look dry like there hasn’t been any leaks.

 

Front and back? Should be top and bottom. The hose that runs from the lower radiator to the block on the driver's side should be hot if the thermostat is opening.

 

yeah that’s the hose I was talking about. I know because I forgot to put the clamp on it when I started it up the first time and heard some sizzling from leakage. Put the clamp back on and it’s not leaking anymore. Good thing about it, is that it’s not over heating when idling for a solid 10-15 minutes. I’m gonna leave it on a little longer to see if it over heats after 15 minutes of idling. Any thoughts if it does overheat after 15 minutes?

 

just keep bleeding it - look into the lisle funnel which will greatly help!

 

I’m gonna do my best. Like I said earlier I’m just really scared to find out I have a blown head gasket.

 

are you pissing out white exhaust?

 

it’s hard to tell because it’s really cold outside where I am. My brother 19’ camero has the same amount of smoke and same moisture on his exhaust when his car was there when I turned it over for a test drive to see if it was fine to drive or not. so I had no idea if it was a blown head gasket or not.

if that made any sense.

*edit*
when I first got the car and turned it over it shook like a old v8 Chevy pick up truck and was super loud like it had a straight pipe.
now that I changed the valve gasket, it’s a lot quieter and not shaky when it’s idled.

 

Good news: my car can idle for about 18 minutes without over heating. So That’s a good sign of no blown head gasket. No leaks or anything.
I’m gonna try to bleed the system out this weekend. Gonna be raining outside for the next 2 days.
I talked to the past owner about when he changed the thermostat and he said it was changed out 2 months ago.
also the oil cap is not milky so no water is getting into it.

 

Sorry if im telling you to suck eggs.....but did you check radiator hoses? if you can squeeze the top one closed too easily then is cactus...suction will close it during acceleration. Have a friend give it a squirt while your watching.

 

I’m gonna do that this weekend. It’s just raining all day today until tomorrow afternoon and I get off by sundown and don’t have a garage to work in.

 

Update
came home from work just now and checked the thermostat. Left hose is nice temp right bottom is cold as ice. Also there was some air pockets in the cooling system too.
buying another thermostat by Friday

 

That will do it. Just ensure to bleed it according to the FSM. Using the spill free funnel that Bealljk mentioned does make the process easier, although it is not necessary. It took me about 2 bleed cycles to get to the point where the car was capable of being driven without overheating, but I still have a small amount of air as the heat blows ice cold when not in motion.

Are you replacing the thermostat with an OEM unit?

 

changed the thermostat. Got it from advance auto parts. Not sure if it’s OEM. Bottoms right hose is still ice cold and cabin is blowing cold air when heater is on. Left it on for 15 minutes and the thermostat was about 75% up at 15 minutes. I know for a fact the head gasket isn’t blown. Trying to bleed the line again in a bit.

 

Well turned the car off to cool down and the bottom right hose got warm when the car was off. I’m really confused.

 

Keep bleeding it. The fact that the hose got warm is an indicator that the thermostat is working, but the ice cold air says you still have air in the system. Do you have the procedures from the factory service manual to follow?

 

no the guy who had it before me didn’t have it. It’s still working if the hose got warm after the car was off? That’s what’s throwing me off. Also I thought I was crazy because I couldn’t find the bleeder valve.. turns out the old owner removed it.