I DTW I

Hi all,

My 350Z (2003) sat for 2 years until I could resolve a misfire. We had 2 babies so it took a
long time. I finally resolved it but while trouble shooting I had accidentally started the car for a few seconds with the coolant hose that goes to the CAI tube disconnected. Naturally the car overheated when I test drove it, I’m sure it caused an air bubble.

The misfire is now fixed (yay!). The coolant looked gritty anyway so I drained it and I’m refilling.

I put the front of the car up on 3 boards and followed the FSM directions to the word. I know this car is difficult to bleed the air out. I test drove it and the car overheated. I then bought the Lisle spill free funnel this forum recommends and put the nose up and idled it to operating temp, squeezed hoses, and did the 3x revs to 3,000. Then topped it off when stone cold. The car overheated again!

Today I did the funnel method again, put front of car way up high, idled to operating temp and squeezed the rad hoses frequently, did the 6x revs to 2500 again. I shut it off and left the funnel in and when the coolant contracted it took less than 1cm of fluid in the end. Car overheated again.

There’s strong heat in the cabin after all 3 times I’ve bled it. The temp never spikes up, only goes up gradually. The fans come on around 205 F but temp continues to go up a degree every 30 secs or so. Sometimes goes down but always up. The other thing is when I rev the engine no bubbles come up in the funnel.

The black line is where the level was when I started this most recent attempt in the top pic. Took less than 1cm after it cooled down to ambient temp.

jhc

Hi. Go to the red bar, tap Search, 》Advanced Search》Search Thread Title》enter "Burp."
Gl!

I DTW I

I've read all the threads I can find on the topic of bleeding/burping the cooling system on this forum and am doing all the suggestions people recommend below and I don't understand why it's not working. I've been a member on here since 2009 so this is not my first coolant bleed. In all the other threads people have no heat in the cabin. I have very strong heat in the cabin. Because of that and since it won't take more coolant, I'd started thinking the air is fully out and the radiator was partially clogged or the t-stat was stuck partly closed and was about to order a new rad & t-stat.

1. The front of the car is up in the air
2. I'm using the Lisle spill free funnel
3. I'm squeezing the radiator hoses
4. Revving to 3,000 for 10 seconds after warm up 3x
5. HVAC is set on max heat
6. I'm letting it cool all the way off before topping it off
7. Did the initial fill slowly so air can get out and until the bleeder port overflowed solid
8. While idling to warm up yesterday I opened the bleed port to look in and coolant dumped out like crazy.
9. I followed the FSM.
10. I've done the above 3 times now

The only thing I haven't tried is in newer threads some are saying put a small funnel in the bleed port. I got curious and opened the bleed port with the engine cold just now and to my great surprise it's completely empty. I don't understand why there's no coolant in there when I've followed all the steps 3x now. I'll put a small funnel in the bleed port and fill it up there next opportunity. Is the heater core go above the height of the heater hoses back there or below?

jhc

^^^; This, perfect!
It's designed to open a 1/2 turn or so with car running. You can also take it completely off and add 50/50 to directly prime hoses and heater core, replace cap and run. Repeat as necessary.
I've always thought this was the best approach. Gl!

Tomek350Z

iTrader: (14)

worse case scenario is you have a compressor, use a vacuum filler tool, it makes life a lot easier

I DTW I

Just an update guys, I filled coolant into the bleed port in the heater hose with a tiny funnel and it finally worked for me.

GreyZ

iTrader: (2)

You are right that getting heat is a good first step.
I would edit your method to the following to ensure a perfect bleed:

Use a vacuum fill tool.

otherwise,
1. Raise front of car until rad cap is level with bleed port
2. Open bleed port completely.
3. Use lisle funnel to slowly fill until coolant comes out bleed port.
4. Put bleed port in a few revolutions and let coolant flow out for 20 seconds. Then tighten.
5. Crank car and let it idle with coolant in the lisle funnel until both the top and lower radiator hoses are hot to the touch and heater is blowing hot. Make sure to keep coolant level atleast half way up in the lisle funnel.
6. Rev to 3000 and hold for 10 seconds. Repeat 3X.
7. Turn off car. Remove lisle funnel and install rad cap. Fil overflow tank to MAX.
8. Lower car to ground.
9. (Car should still be hot, but about 10 minutes after you turned it off). Crack the bleed port and let coolant come out for 5 seconds or so. Then tighten.
11. Let it cool completely
12. Go test drive and make sure it does not overheat.
13. Repeat steps 9-12 until you do not get any air out of the bleed port. Make sure to top off overflow tank to MAX as needed.


If you follow these steps, and still overheat then you have other issues.

I DTW I

I finally had time to look at the 350Z again. I figured out why I had such strong heat and yet the car kept overheating even when I’m following all the directions. The left radiator fan was not spinning!! At the very beginning of this overheating saga, I had checked and saw both fan spinning so it must be an intermittent problem. I hadn’t checked the fans since then because I heard them come on loud and clear. Well, I thought I heard fans come on. Actually I was hearing fan (singular) come on and my ears couldn’t distinguish the difference so that’s why I never suspected the fans. I just removed the fan assembly and the new one is on the way.

i8acobra

iTrader: (6)

Once you replace the fan, let the car run until the temp gauge shows normal operating temp, then feel the lower hose. If it's not hot, your thermostat is stuck closed. This happens often in VQ motors that are parked for a while.

Escobar

iTrader: (27)

good advice there, these can be a pain. I just went through this with mine but it went pretty smooth. the bleeder hose by the cabin is very helpful.

I DTW I

Thank you for the advice everyone who posted. I replaced the fans and it’s fixed!!! Now how on earth did the left fan fail at the exact time I was bleeding the coolant!? That’s what led me to expect I had air in the system since it’s hard to bleed. Check that both fans spin people when your A/C is on or coolant temp is above 206 F.

I’m so excited to drive this car again as it’s been so long!!

Escobar

iTrader: (27)

nice, thats a crazy coincidence. go take it for a rip