I sure am glad I found this forum. I used to use the370z and it has sadly gone offline. Tons of info there.

Anyway, I have a basic question about bleeding the coolant. I have a no spill funnel. I lift the front of the car a bit with the funnel on, fill it 1/3 or so, turn on the engine to let it warm up, heater on low, ac off, rev the engine until bubbles come out.

My question is - I keep the reservoir cap on during this entire process right? Anything I am missing?

 

Dang. That sucks about the 370z forum. You can use this: https://web.archive.org/web/20250808...w.the370z.com/ It is slow, but it still works to an extent.

Not familiar with the proper bleeding procedure on the Z34, but I'm guessing it should be similar to the Z33. For me, I've found the best way to purge all the air out of the system is the following:

Have the front raised up with your no-spill funnel on the radiator.
Fill the reservoir to the MAX level. Then, keep the reservoir cap screwed on for the remainder of the process.
Remove or loosen the bleeder screw located near the firewall.
With the engine off, slowly pour coolant into the funnel until you see some excess coolant come out of the bleeder screw. Reinsert the bleeder screw once this happens.
Go back to the front of the engine and squeeze the upper radiator hose which will cause air bubbles to appear in the funnel and also suck coolant in. Once there are no more huge bubbles coming out, fill the funnel to about 1/3.
Turn the engine on and crank the heat to get coolant to circulate through the heater core. Half power is probably fine.
Rev the engine to 2500-3000 rpms a few times and hold until it gets to operating temp and the thermostat opens. The fans should kick on at this point. You should see more bubbles coming out of the funnel once the thermostat opens and starts circulating coolant through the block.
Squeeze the upper radiator hose during the process to help out any stubborn or stuck bubbles.
Also, crack the bleeder valve and you should hear some air hiss out.
Let it cool down. Verify that the interior heat is working when at idle. If not, or you have overheating issues, repeat as necessary in order to get all the air out of the system.

More than likely, you'll have to bleed it multiple times since it's rare to get all the air out on one attempt.

Good luck!

 

Thanks for the info!! Yes I think it's the same for the 350. So I recently changed a coupler and replaced it with a bleeder now it's the same as the 350. During this process I tried to bleed it with the bleeder. I didn't have the funnel yet. The heat works fine at idle, oil temp is 220, water temp never goes above normal. But I don't think I got all the air out, that's why I want to do this. If I fill the reservoir max and no air comes out, should I suck some fluid out so.its below the max line? Thanks again!!

 

If you have a spill free funnel, use that instead to get large pockets of air out. Use the spill free funnel on the radiator and partially fill it, this moves the highest point of the cooling system to the funnel, having the front of the car jacked up or on ramps can help with this. Then follow the warm up procedure outlined by Heel. Once the thermostat is opened, I like to let the engine idle for a good 20-30 minutes, periodically revving it up to 3-4k RPM in short bursts to help push the bubbles out of the engine, into the radiator, and from there out the funnel.

You may still get/have micro bubbles in the cooling system after a drain and fill service. These will eventually purge themselves after multiple days of normal driving (heat cycles). Just monitor your overflow tank and top it off during the 1st week of driving.

Why do you think you haven't gotten all the air out? If your heat is working and your temps look good, it sounds like you've done it right.
Cheers!
-Icer

 

Thanks for the additional advice, I'll do that to make sure. The only reason I don't think, or least I am not certain, that I got all the air out is because I replaced the coupler and some fluid came out and there was definitely air in the system, and it sounds like these are hard to get all the air out of. I didn't use a funnel or anything, I just opened the reservoir cap and opened the bleeder valve a little and squeezed the upper hose, etc. but it sounds like that isn't really enough to get all the air out normally. Maybe all the air is out.

 

When you say you replaced a coupler, are you referring to the air bleeder coupling on the heater hose? I'm not super familiar with the 370Z engine layout, but I imagine it's very similar to the 350Z. The bleeder port is located on one of the heater hoses next to the battery box on the back passenger side of the engine bay. If this is the coupler you're talking about, then I presume it has a screw you can open to let out any trapped air. Get a rag ready to catch coolant, and crack open the port while the engine is off. Once coolant starts coming out, close it up and you should be good.
Cheers!
-Icer

 

Exactly, that's the one! Same layout. On the 370z, they decided to remove the bleeder valve and just make it a coupler, but z1 sells an aluminum coupler with bleeder so it is like the 350z. Well I didn't think it was that easy, why does everyone mess with the funnel and such? Perhaps I'll return mine, I haven't opened it yet. Or maybe I'll just do the raised front no spill funnel bleed procecedure to be extra super 100% sure.

 

The bleeder screw is really supposed to be used when doing a coolant flush (full drain and refill). You keep it open while filling with coolant at the radiator. This bleeder allows the air to escape as the coolant displaces the air introduced during the drain process. As Heel mentioned earlier, you close the bleeder once coolant starts coming out of it. Failure to observe this vital step will leave you stuck with a huge amount of air trapped in the heater core, which can be very difficult to burp/bleed out.

The are great to have around as they are universal (pretty much all makes and models work with them). Also it's worth noting that coolant should be replaced every 3-5 years (some modern coolants claim they can last up to 10 years), failure to do so will allow for the coolant to chemically break down and become acidic, leading to corrosion issues in your radiator, heater core, hoses, engine block, etc... So I would keep it if you're confident you can do coolant flushes in the future.
Cheers!
-Icer