FOOKhonda

iTrader: (1)

So today I noticed my car was about 3/4 of the way up to H. I had drove for about 15 mins and didn't notice it til then. I turned it off and got back in about 20-30 mins later and it was fine. I went and got gas, then went to pick up the gf about 5 more miles down the road, after about 2 more miles I noticed it was slightly over the 40-45% range it usually sits at. I turned the heat on and it went up fast so I immediately turned it off and it went back down quickly, It didn't seem to get hot while sitting at a light, and would start to warm a bit when taking off but once is get to about 30+ it'd drop back to about 50-55%.

When I got home I let it cool off, then I checked coolant it was still full, used maybeee 1/2 cup to fill it to the top again. It's not leaking anywhere, no weird noises (grinding or anything) the inlet radiator hose was warm after checking everything, then I started to check it to feel water flow and it got hot. Hose from radiator to thermostat stayed cool. Fans are working fine.

When I first started it I took the radiator cap off to see if it was pushing coolant out to see if it was pushing pressure, but it never really came over the top.

Tomorrow I'm doing a radiator flush to rule that out, but in the meantime I was wo.seeing if this sounds like a bad thermostat or if the water pumps going out?

I did all the checks from my Chilton repair manual and everything seemed to check out. I'm wondering if the thermostat may be stuck at only like half open or barely open, and properly cooling at idle and not driving?

If its the thermostat I'm thinking about doing a open thermostat so I never have to worry about it closing, and can always rule that out in the future.

Thanks in advance, if mods are in question they are in my Sig.

06 5at DE.

dkmura

iTrader: (64)

Before you go any further, try replacing the rad cap. They do go after awhile and have the same symptoms you're describing even if you check them cold.

FOOKhonda

iTrader: (1)

It still looks brand new, like it just came out of the package. Seemed to be sealed tight.
Still worth replacing it even though it seems new?

Most of the ones I seen go bad were in terrible condition so didn't think about doing that.

FOOKhonda

iTrader: (1)

Update - so not really sure what's going on now, I had to go up to the store which is about 1-2 miles away, the temp got right where it usually sits by the time I got there. I left it running with the gr in the car to watch the temp. It was still there when I got back, bout 3 mins later, then I pulled out and was almost home and temp still was fine so decided to drive about 2 miles past and turn around to come back, still nothing. When I got back I left it in drive and turned the heat on ( this made it go up immediately last time) still nothing.. turn ac on, nothing, heat back on, almost to 90 a few clicks away, and turned it up to blow faster, nothing. Did the same with ac, again, nothing. Didnt budge a bit. Maybe the cap came loose or an air bubble got in the radiator at some point? I squeezed the lines a few times with the cap off, and I seen a few bubbles come out, but I've seen that before so thought it was normal.

Is this at all possible? I haven't messed with the radiator since the last time I checked coolant about a month or so ago. Also I put some coolant in the overflow tank again, although it never had any in it and was never a problem before, and Chilton says its for hot coolant to cool off, so its not using hot coolant

Any ideas? I'm lost at this point...

Edit also, this was the amount of miles/ time driving it took the other two times for the problem to appear, but nothing this time, and the reason I left it in drive was to simulate being at a light in case that had anything to do with it.

Spike100

I wonder if your thermostat might be intermittently sticking?

FOOKhonda

iTrader: (1)

Yeah I was thinking that, but this was the first time its happened for the about a year I've had it now. So if it is its just starting to mess up, I will most likely replace it this Friday and avoid it possibly going out at some point and not be able to fix it.

Also will replace the rad cap to rule that out in a possible future issue.

mr. sparco

iTrader: (13)

Overflow tank should always have coolant in it, hot or cold. Mine had coolant in it the day I picked it up with 5 miles on the odo.

The_Assassin

Hey man i had this same problem about 5 months ago in my 07 z. Car would not over heat at idle. The reason why it heats up quickly when your ac is on is because ur radiator nd fans might be going bad.

Mine only 1 fan worked. Had to change rad and fans. Also check thermostat that could be a part of it also.

FOOKhonda

iTrader: (1)

When i bought it never had coolant in the reservoir, and that was during the summer and I never had any problems, eventually I bought coolant and put some in it anyways to be safe. And i put some in it this time as well.

Assassin, I don't seem to have problems with the ac being on distinctively, it was when I turned on the heat that the temp went up very quickly. I could hear the fans working, and I checked them later and they worked fine, and since ive had this issue it has not happened again, and I've drove probably near 100+ miles and still no issues. I'm thinking it was a small air bubble or the rad cap was loose, although it didn't seem loose when i took it off.

che69velle

Its them gremlins I tell ya.lol I had the same problem, it was an air bubble.

FOOKhonda

iTrader: (1)

Lmao, I think I was air but who knows, haven't had a problem since so only time will tell.

FOOKhonda

iTrader: (1)

So, this finally happened again this morning, I got it to the courthouse before it got too bad but it was sitting about 50-60% almost the whole way, once I got out of court, about an hour later I pumped on all the lines for a little bit, and now no problem again... I'm thinking either the thermostat is slowlyyyy going out or something is causing air to get in my lines, I'm going to go ahead and replace the radiator cap, but in the meantime, do you guys have any idea how I could be getting air in the lines? Ive never seen any leaks or anything so highly doubt there's a small hole in a line somewhere...

woody03

iTrader: (5)

Thats a weird one. Are you low on coolant? When my cap was bad I couldnt get fluid back from overflow.

FOOKhonda

iTrader: (1)

Nah, its completely full, I put some extra in the overflow causeit was getting kinda low, but still having the problem, last time after I pumped the lines and stuff it was fine

woody03

iTrader: (5)

Are you sure air is getting in the lines? I guess it could be the tstat going put or even the pump not working properly???

FOOKhonda

iTrader: (1)

I'm not 100% sure but it seems likely since I pumped the lines and never had another problem for bout 3 months, I could easily be wrong but I surely hope its not the pump... Lol

FOOKhonda

iTrader: (1)

So think i may have solved my problem but I don't know for sure yet. But just checked my oil 4 times or so cause I was shocked... oil was about half way between L and H.. what's weird is I know this wasn't my problem the first time, and the issue is pretty much exactly the same. But I think ill replace the cap and change the oil and bleed the lines and see what happens, if its still happening I'm going to take out the thermostat and make it constantly open, I'm not going to play guessing games again.

FOOKhonda

iTrader: (1)

Well I changed the oil and radiator cap, I hate the dipstick though, so hard to get an accurate reading... but so far no overheating, maybe the radiator cap was the problem...

Spike100

^^ I also hate the 350z’s dipstick. It’s very hard to read. There are suggestions on this site on improving the dipstick. These include notching the dipstick and deepening the crosshatching.

A faulty radiator cap (one that seals poorly) can cause all sorts of problems. Same goes for a poor seal with your gas cap.

Question: Do you ever see any white colored exhaust?

--Spike

FOOKhonda

iTrader: (1)

Yeah I've thought about doing that, but usually what causes it to be inaccurate is that oil will show all over the dipstick and then will only show very lightly where the markings are..
I believe creating a couple marks across May help a bit though.

And kinda but not really, like when i had the car dyno'd when they floored it I seen a teenie tiny bit come out on the first pull, but never seen any on the other two pulls, and when I say teenie tiny I mean almost unnoticeable and it quickly disappeared, almost like it was just vapor.

When I did my first oil change I didn't push the dipstick in alll the way so it ended up blowing a bit of oil out, it was nowhere near the thickness of that smoke, and I've never smelt burning oil other than that as well.