Hey guys,

I'm a frequent lurker, not much of a poster here.

I'm not sure if this should go in the repairing section, but I think it's a general 350z question.

Anyway, I own an 04 350z touring. I've been noticing that when I turn the car on with a cold engine, and rev the engine, there's a fluid moving sound coming from somewhere in the engine. It happens whether it's in park, or actually in gear (I have an automatic if it makes a difference).

It only happens on first starts/ cold engines, and only the first few times I rev it. I'm mainly curious to know what that sound is. What fluids are moving around in the engine that cause the sound, and should I be concerned?

 

no clue what that might be, but i wouldn't recommend revving much over 2k with a cold engine. until those fluids warm up, that's one of the worst things you can do to an engine.

 

^^ Agreed...

If I'm in a hurry, I drive under 2000rpm or even under 1500 rpm. I usually rely on oil pressure and not passing 3/4 (80 psi I think? mine reads 6kpa, stupid canadian and their metrics...).

 

when my wife drives the car, that was one of the 2 rules.
rule 2: never press the TCS button (i'm exempt from this rule

 

Why would you do that????
bill

 

I will add one more: "don't do that" to revving a cold engine.

I would also first check your coolant level and then follow the procedure to purge air from the coolant system. Coolant passes through the firewall into the heater core of your A/C system. It's possible there is an air pocket trapped in there that needs to be "burped."

I seem to recall a thread or two on this before, so try a few different searches and report back. I know you're a lurker, but now that you've chosen to make a request, you're obligated to report the solution to your problem so that future searchers may find the thread helpful. Good Luck!

 

Let your car idle for 5-10 minutes if it's a big deal to you. That way the engine fluids can get moving again before you "rev" it up.

 

I always let my engine idle until the temp rises. Even if its 80f outside.

 

Sorry by revving engines, that's what I meant. Just turning it on and letting it sit there warming up. Wrong word choice on my part.

But even when it's on and idling warming up, I still hear the sound. It's as though fluids are going through the engine or something, but I know it's not something I hear when the engine has already been warmed previously.

 

Also 350Zenophile, would the AC system be an issue if I leave it off when turning the car on?

 

Coolant will be pushed by the water pump regardless of engine temp but I don't think it will flow through the heater core unless the A/C is set to "hot." I say this because all the instructions I have ever read and performed for a coolant fill/flush have you turn the heater on high during the procedure.

Its really the only fluid in the car that could be making the noise you're describing.

 

unless a car has a dedicated coolant cutoff valve, coolant will always run through the heater core.

i'm pretty sure the noise is the coolant. check for air bubbles.

 

You should get a Factory Service Manual for your year Z. Read the attached...this is from the Engine Cooling System section:

 

sounds to me like your p/s system. this usually happens to older cars or if the fluid is low. check that! otherwise if you live in cold climates it takes a while for the fluids to get warm and change viscosity so its easier for it to move. just let ur car warm up and you'll be fine unless the noise is still there after its warm!!

 

Thanks guys. I haven't had a chanec to check this out yet, but like I mentioned, I'm pretty sure it's nothing serious as its a sound I only hear while the engine is warming up. For what its worth, I live in a warm environment (SoCal) but I will check into and perform the engine coolant "burping" this weekend and see if that solves the issue.

Thanks again for the help. Exactly why I lurk at this forum

 

i had the same prob and it was the fluid level of the coolant and windshield washer fluids. They were low!

 

I have heard this also for a few brief seconds when the car first starts up and then no more, and I have a 2006 Z with 2,700 miles on it.