On my redline performance, I notice a quick THUMP sound during startup when its been siting for several hours. I've only started it cold maybe 5 times, it has done it each time. It also only has 175 miles so I don't know if this is just a breaking thing, my black performance never did this but I broke it in over a 2 day period so this didn't apply.

No, its not kittens in the hood, I already checked!

 

what kind of thump sound? was your car rolling when the sound came up?
I have a "grown" sound when my car rolls forward (rolling down the hill, since my house is in some sort of a slope) during startup.

 

The thump is kind of like someone hits the hood moderately with a flat hand, although noone is around to hit the hood with a flat hand!!

 

When i first started her up, and i was in first gear going prob like 10 miles an hour if i quickly pushed in the clutch i hears a lound thump, i have not drive this car hard at all so i was getting really worried then it went away hasnt come back since ? i dunno

 

I just heard it this morning and I have 2500 miles on the car. I noticed that my A/C was on and that may be the problem. I'm gonna have the dealer look at it.

 

I think the thump at engine start is the ABS testing itself. I read that in the manual. Check it out.

 

I too have been having the thump on initial start-ups. It seems to be coming from the bottom area of the drivers side. From what you have explained, it sounds exactly the same. Not noticeable after the car has been warmed and started. Wonder what it is???.......Ricky 6spdTour

 

I hear the thump as well in both of my Z's. One has 3k and the other 1k and both have done it since new. I figured it was normal since both of my Z's did it but it hasn't bothered me enough to go to the dealer and complain thus far but good to know that others hear it as well so I don't think I'm crazy.

Eddie

 

THANKS!!!
maybe thats what I have been hearing all these times!!

 

Ditto here - I only hear it after the car sits overnight. To me it sounded like it came from the driver's-side dash. At first I thought it was the stereo, but then it occurred when the stereo
was off. I will also check out the manual.

Nissan needs to warn us about strange bumps, thumps, and clunks that are normal & nothing to worry about.

Ever fly and wonder about the weird noises (flaps going up or down. etc.)? - always wished the stewardess or pilot would explain those noises. "No, it's not an engine falling off. Please get away from the emergency exit".

 

I think that's what the owner's manual is for.

Page 5-21:

Self-test feature

The anti-lock brake system consists of electronic
sensors, electric pumps, and hydraulic solenoids
controlled by a computer. The computer has a
built-in diagnostic feature that tests the system
each time you start the engine and move the
vehicle at a low speed in forward or reverse.
When the self-test occurs, you may hear a clunk


Folks might want to read the thing. It really does have a few pieces of information about the Z that you should know about.

www.courtesyparts.com/350z/2003-Nissan-350Z.pdf

 

The key point to that is it says "when you move the vehicle". The thread is talking about a clunk at start up. Every vehicle that has abs makes a noise that is not necessarily a clunk that comes from the drivers side. The clunk is not really bothering me but I do agree that it is very noticeable upon starting cold. That clunk that you hear with the abs per the manual is heard everytime the car is started and makes no difference with temperature. Just thought I'd point that out and Sage, I'm not taking a shot. It seems that a lot of bickering starts very easily in these threads and I don't want you to take it that way but a very good point made about the self test.

Happy Thanksgiving!!!

Eddie

 

I have the clunk too. Seems to be more prevalent with colder weather, but we haven't been having much. I'm going to try starting it in neutral now and see if I ever get the clunk again.

 

I'll be taking the car in for an oil change in a couple of weeks and I wil see what the service people have to say.

 

also heard it for the first time a couple of days ago. the car had been sitting in the garage for maybe 3 days. it has 3500 miles on it.

 

Damn, people. We're getting silly around here. That "thump" sound is the initial intake charge. That's all. Your cold engine is sucking cold air. Ever stick your hand in the intake when someone's revving the throttle? It's like a vacuum. Yes, it's that powerful.

Stop this thread NOW.

 

I can buy the intake charge idea, but how does this create a knock? What's knocking?

 

Thanks for this thread. I have a Nissan Pathfinder, and have always had a "thunk" after I started it up and moved.

Now I know what it is, its the ABS!

The Pathfinder manual has the same in it