My car has had air in the lines for some time. Its the situation where the heater will blow cold until you get on the gass and the coolant makes it back into the core. Occasionally the temp gauge would rise when sitting still and go back down when I start driving.

Tonight, The temp gauge went higher than ever, yet the heater was still putting out hot air. It seemed to drop a little when I was driving but never back to normal. I managed to get back to my development when POOF, Antifreeze odor and white smoke pouring from the driver side firewall throttle body/head area under the hood. It was too hard to tell if it was coming out of the exhaust or if it was just blowing back from the hood when I was driving that last 1/4 mile.

I do have a plenum spacer installed. Could coolant leak from that gasket? I have a friend coming by tomorrow to do a leakdown/compression check on it. I have done HG on FWD transverse cars like Hondas, but this would be the first time I've had to dig into my Z. 2004 5AT 140K miles.

What steps should I take to diagnose? I was thinking:

Top off the coolant
Run to temp, check bottom radiator hose and if it gets hot look for leaks.
Do the LD/Comp test.

Any other tips? I need you guys right now. Thanks!

Torrey

 

Hmmm I would like to know too. My car must have air in the lines too... My heat blows cold unless I'm driving down the road.

I've never seen the oil temp or anything get high or above normal, should I worry?

 

Get the Z up on jackstands and take a good look underneath. Before going any further, nothing beats getting underneath and having a good look yourself. Take a close look at where the coolant is puddling on the floor and trace it back to the source. Could be a coolant line to your heater has been damaged or leaking.

 

Thanks. Does the motor need to be pulled to do heads on this car?

 

I would think to check all your coolant hoses - especially on that side of the engine...if they are leaking all over your headers/cats that might explain the rush of smoke.

You'd need to pull the block to replace the head gaskets...some might say that it is possible but you'd be doing yourself a dis-service by attempting this in the car...

I just did mine this fall, not impossible if you have the right tools/equipment, a copy of the service manual and patience/time on your side.

my tips would be take your time, label everything, organize everything and be absolutely as methodical as you can be.

 

Oh christ....

 

YESSSSS ITS NOT THE HEADGASKET!!! The ****in line for the throttle body had a bypass barb from when I installed the plenum spacer. The barb cracked in half and that was the leak. Problem seems to be the thermostat because the lower hose isn't getting hot. I also have a ton of air in the system. Could the tstat no be opening due to the air issue or air they two separate issues? Temp was 228 and holding.

 

you may have solved the coolant leaking on an hot exhaust element but air in the cooling system may be due to a failing head gasket...you're not quite out of the woods.

If the lower hose isnt getting hot that means the coolant isnt cycling, most likely because your thermostat isnt opening. Testing your thermostat is very easy - take it off the car and dip it in boiling water, you should be able to see the mechanism open and close.

If you have air in your cooling system then it means air is being forced in. The cooling system runs at ~15-20psi, so when your car is at running temp then it is purging itself. So something has to be greater than that to push air in your cooling system. If your headgaskets are failing then your combustion is forcing air into the cooling system. If you have air bubbles sitting behind your thermostat (and not hot coolant) then it is not going to open.

fill up and bleed your cooling system, get your car to running temps and have someone watch while you driver around or run the engine at 2k - 3k and take note of what color the exhaust is.

 

I was thinking the hose to the tb myself. I would make sure you have all the air out the system before replacing the T stat. It's probably been leaking a while.

 

Problems. We swapped the Tstat. I tested the old one and it opened about 1/2". Is that correct? Pulled the lines to the heater core and flushed it with a hose with no issue. Filled the cooling system and it didn't seem to be bubbling in the spill free funnel or at the purge valve. Temp held steady at 203-207 at idle with the heat on. Heat was blowing warm at idle as well. Still, the lower hose was not hot.

Took it for a hard test drive and after 5 mins steam from under the hood. pulled over and the radiator is leaking like a sieve at the top along the seam where it is put together. Car overheated and got op to 255. Got it home and parked it. Ordering a radiator.

Any input? What procedure do you guys use to purge the system properly?

 

holy **** you took it up to 255degrees!!!

 

Good q, phreaktor-after you change out the radiator AND bottom hose, fill the radiator and reservoir to level. Make sure you know how to "Burp" the heater section also- this was a major source of air for me. GL

 

^How do you burp the heater core?

Leaving this here for reference:

https://my350z.com/forum/attachments...g-circuit2.jpg


Here are cliff notes of how to bleed coolant in the Z:

1. Install spill free funnel.
2. Fill funnel with coolant.
3. Start car
4. Rev car to ~3k rpms, hold for 10 second, return to idle. Repeat about 3 times.
5. Open bleed valve, let air escape, close bleed valve when coolant starts to run out.
6. Repeat step 4
7. Repeat step 5
8. Repeat step 4
9. Repeat step 5

....On and on we go until all air is purged.

Some advanced tricks:

1. Park car so that the front end is elevated higher, or jack up front end. This helps air escape easier.
2. Squeeze the upper coolant hose repeatedly, you will see air bubbles coming up thru the spill free funnel. Rev engine as described above, and repeat upper radiator hose squeezing. Continue until no air comes up into the funnel.
3. Drive the car around for a while. Allow car to cool all the way down. Now repeat this whole process - if you get no more air you are done. If you get air, you need to keep bleeding.


ANOTHER ONE:

NOTE IT IS CRITICAL THAT THE FOLLOWING PROCEDURE BE FOLLOWED EXACTLY! IT IS TIME CONSUMING, HOWEVER, ESSENTIAL!




3.1 Remove bleader in the stock upper heater hose.



3.2 Fill radiator and coolant recovery reservoir with anti freeze coolant. It should take 10 quarts, including reservoir. It is important that the coolant is poured through the radiator filler neck at less than 1.5 quarts per minute, in order to allow air in the system to escape.



3.3 When the engine coolant overflows the at the bleader, re-install the bleader


3.4 Warm the engine to the normal operating temperature with the radiator cap installed.



3.5 Run the engine at 3,000 RPM for 10 seconds and then allow it to return to idle speed.



§ Repeat this action three times.



3.6 Stop engine and allow coolant temperature to drop below 120°F.



Use a remote electric fan to assist in this process.
If necessary, refill the radiator and reservoir up to the filler neck.


3.7 Repeat steps 3.3 to 3.6 at least two more times (it may take more) with the radiator cap installed, until the engine coolant level no longer drops.



3.8 Check the cooling system for leaks with the engine running.


3.9 Fully warm the engine and listen for the sound of coolant flow through the heater unit, inside the car; while running the engine from idle to 3,000 RPM, with the heater control set at several positions between cool and warm.



· Repeat this action three times



3.10 If any sound is heard, continue to bleed excess air from the cooling system, by repeating steps 3.3 to 3.6, until the coolant level no longer drops.


***...... the use of the tower funnels helps push air out.

 

255 is really freaking high. Did you try flushing the radiator? if its coming out clear its probably not clogged. Jacking up the car helps but also the side with the bleeder. I honestly didnt have trouble bleeding my car at all after doing the PPE headers.

Take it for an easy driver before a hard one. Hopefully you didnt damage anything.

I think some people over-dramatize bleeding the coolant.

 

Radiator just came in. Dropping it in tomorrow and flushing/refilling/purging.. I still don't know what cause the radiator to blow up at the seam of the top tank. Obviously some sort of pressure but from where? Its never been an issue with the radiator before we started swapping the thermostat and purging. Still don't know why the lower hose wont get hot but its a new thermostat. Air pressure keeping the fluid from reaching? How can I flush the block to see if it is clogged and where is the drain plug for the block?

 

Radiator back in. Same issue with elevated heat level, but not over heating. About halfway on the gauge. Tiny bubbles coming up every few seconds in the spill free funnel. Did two rounds of letting the car cool, restarting, cracking bleeder valve (air from the valve the first time and about to check it again.)

I'm getting a knocking noise coming from the radiator. Anyone know what this is? The coolant level in the funnel spiked to almost the lip of the funnel when the car is running then goes back down to the level it was at before I started the car. IS this normal? Trying to get this done tonight before the cold weather this week and I need my car.. Thanks

 

Hey man,
Sorry you're still sorting it out. When my heater quit working I simply added coolant to the bleeder line to fill the heater core till it overflowed, and topped off overflow a couple times. Worked for me.

GL

 

Well now I have managed to break the tube on the bleeder valve. Does anyone have that part number? I don't see it here: http://www.courtesyparts.com/350z-pa...5_736_740.html

Here is a video of the situation:

 

In addition to my other questions, what does letting the car cool down between top offs do?

 

Isn't there a burp/purge valve under the cover "brake" up by the cowl to help get the air out? I can't remember and my car is tucked away for the winter but I seem to remember reading about this issue on our cars and getting all the air out of the system......I may be wrong