Rattling Sound During Start-Up

[MTV]

Every morning I get to my car after it's been cool all night and I start it, there's this rattling sound that lasts for a split second, right after I start the car.

If the engine is warm, it doesn't happen.

What could this be?? I have a feeling it's the motor mounts causing this...

Oh and I removed the heatshield that is covering the headers, so it's not that.

Matt

[redpr5]

Every morning I get to my car after it's been cool all night and I start it, there's this rattling sound that lasts for a split second, right after I start the car.

If the engine is warm, it doesn't happen.

What could this be?? I have a feeling it's the motor mounts causing this...

Oh and I removed the heatshield that is covering the headers, so it's not that.

Matt

it could possibly be the bearings in your alternator. mine did that too and my alternator was shot
or it could be vtcs (IIRC) it gives the cold start rattle

[zoomzoom02]

Mine does the same thing. Has done it for a few years...105,000 miles and still going strong - just burning oil.

I have no idea what it is though, so expert advice would be helpful to me as well.

[aMaff]

probably the VTCS. I'm pretty sure there's a TSB for that to recalibrate how it works @ startup, but it's generally not a big deal.

[JoshP5]

+1 VTCS, but I don't know about the recalibration. That crap just rattles.

[thrasher]

Mine rattles too, just for a second, then it's gone.

Sounds like a heat shield, but I haven't found it yet.

[silver storm]

Mine was a galled rod bearing. Hope it's not the case with yours since you're out of warranty. The noise I heard would only be heard for less than a second right after a cold start when the car had been sitting for at least 6 hours. Outside temperature was not a factor.

http://www.mazdas247.com/forum/showthread.php?t=123679370

[melicha8]

LOL P5 noob it's the VTCS

[silver storm]

LOL P5 noob it's the VTCS

Thanks melicha for the wonderful insight and value added comment. For the owner's sake, I hope you're correct.

However, just since I'm a "noob" on this particular forum doen't make my observation or suggestion any more or less qualified than yours. VTCS was the VERY first thing diagnosed on my car as NOT being the problem.

Cheers. Have a nice day.

[Cellerator]

Mine rattles too, just for a second, then it's gone.

Sounds like a heat shield, but I haven't found it yet.

Go check your B&M clearance to the heatshield. I had that issue before and after I bent the top of the heatshield down closer to the midpipe.

[MTV]

Go check your B&M clearance to the heatshield. I had that issue before and after I bent the top of the heatshield down closer to the midpipe.

It did it even before the STS install...

Thanks for the insight though.

[MTV]

Umm... what's VTCS?????

[Demoniam]

pressing the search button at the top of the page: 1 click
Typing "VTCS" into the search field and pressing enter: 4 keys +1 click
Number of results from said search: 500

Finding things out for yourself: Priceless

===============================
Keep in mind that I'm not flaming you, but you have been here long enough to have seen "vtcs" many many times!

[MTV]

pressing the search button at the top of the page: 1 click
Typing "VTCS" into the search field and pressing enter: 4 keys +1 click
Number of results from said search: 500

Finding things out for yourself: Priceless

===============================
Keep in mind that I'm not flaming you, but you have been here long enough to have seen "vtcs" many many times!

ok... now in the time it took you to type all that up, you couldn't have just explained what VTCS is???

[MTV]

So what is it?

I searched it and all I know is that it has something to do with the intake manifold and that people tend to remove it.

Matt

[Demoniam]

http://flatblack.somethingsomething.org/p5/porting/

[igdrasil]

I have a mitsu that does that 50/50 on mornings or after 8 hours, but I already know its a rod bearing clearance issue.

You need to at least check where does the noise comes from...is it louder from the bottom of the engine? prolly rod bearing, if from top, vtcs from the intake mani.

[GlowstickNinja]

Could also be Clutch rattle. Known issue for P5's. I think there is a TSB for this but from what i heard it doesn't make a huge difference after you get the ecu programming......

[ho bag]

Mine did the exact same thing.

I was told it was not the VTCS.....Knowing they were full of sh!t i removed it anyway and guess what....

Its gone now! no noise at all.

[MTV]

http://flatblack.somethingsomething.org/p5/porting/

Thank you.

[thrasher]

Can someone please explain WHY the VTCS makes that noise?

Isn't it just a set of butterfly's on a solenoid? How exactly would they rattle on startup and never any other time?

[aMaff]

because they're only active at startup and while the engine starts up. Once that's done, they go to full open and stay there.

[P5inder]

Mine does exactly the same thing.

Funny enough, it sounds like the exact same thing that my 2000 Neon did. On the Neon though, it was the sound the out-of-round pistons made before they warmed up and allowed the rings to seal properly.

I noticed that on the P5 the sound becomes apparent more frequently when the oil level is low.

Although it might be the VTCS, you might want to check your oil level too.

[MTV]

Mine does exactly the same thing.

Funny enough, it sounds like the exact same thing that my 2000 Neon did. On the Neon though, it was the sound the out-of-round pistons made before they warmed up and allowed the rings to seal properly.

I noticed that on the P5 the sound becomes apparent more frequently when the oil level is low.

Although it might be the VTCS, you might want to check your oil level too.

I check my oil everytime I wash the car (twice a week) and top it off once per week.

Yesterday afternoon I topped it off and this morning I didn't hear the rattling. I'll make sure I pay attention to it whenever I top my oil off.

Matt