Motor Clacking

[03.5rossman]

Having an issue with my motor, just wanted some opinions on what it might be. Basically if the car has sat for a while (couple hours) or initially when the car starts, the motor sounds rough. It makes this clacking noise near the front of the motor and gets louder with a little throttle. After the motor idles down and has run a little bit it goes away. I've also noticed that when the car first starts and I start to drive it, when the turbo kicks in (if the car hasn't warmed up yet) it doesn't sound like a constant air pull. Sometimes it's intermittent and sounds like it's gasping for air. After that first initial start-up, idle, and turbo spool the motor seems to run fine. Anyone have any insight as to what this may be?

 

[Preferio]

VTCS plates in the intake manifold.

 

[malcantry]

spun a rod. same tick in my block. had to get the crank ground and oversized bearings. went forged and doing things right now.

 

[Preferio]

spun a rod. same tick in my block. had to get the crank ground and oversized bearings. went forged and doing things right now.

Since when does rod knock go away?

 

[powderider87]

are you sure its not a exhaust leak at the mani?

 

[Jo060]

spun a rod. same tick in my block. had to get the crank ground and oversized bearings. went forged and doing things right now.

You're crazy

 

[Preferio]

are you sure its not a exhaust leak at the mani?

Yeah, that's very likely and you're probably right...

 

[IshSonP5]

VTCS plates in the intake manifold.

+1, mine did the same things until I removed the vtcs

 

[03.5rossman]

Going to check on the vtcs this week since I got Wednesday off. If not that I'll check the exhaust manifold while I'm in there. Thanks for the responses fellas.

@IshSonP5, when you removed the vtcs, did you start having any error codes or anything come up? -"My original plan was to remove the valve completely but that might throw some obscure CEL/sensor problem" -mazdaspeedy.com and what about sealing the holes on the bottom of the manifold?

 

[njaremka]

Going to check on the vtcs this week since I got Wednesday off. If not that I'll check the exhaust manifold while I'm in there. Thanks for the responses fellas.

@IshSonP5, when you removed the vtcs, did you start having any error codes or anything come up? -"My original plan was to remove the valve completely but that might throw some obscure CEL/sensor problem" -mazdaspeedy.com and what about sealing the holes on the bottom of the manifold?

you can remove the VTCS "shutters" and leave the actuator valve connected. this will prevent any CEL codes, and make the outside still look completely stock.

 

[03.5rossman]

Found an exploded diagram and service manual, doesn't look too entirely hard to pull the shutters. You guys know if there is any noticeable difference with the shutters off? I understand how they work, but I don't see the functionality in them because they are delaying air flow when the accelerator is pushed. Am I thinking wrong? I feel like without the shutters the car will react, maybe milliseconds, faster.

 

[IshSonP5]

They are only there for cold start, other than that they get in the way and restrict airflow. And mine is just the butterfly shutter things removed. I left the actuator and no CEL.

 

[03.5rossman]

Awesome, I appreciate it guys. Will post results Thursday.

 

[jdwk]

The VTCS shutters open when the engine reaches 3k rpms, the temp is over 176 deg F, and the throttle is over 75%.

I don't know if idle is any rougher without them but I would guess it is negligible. From my understanding, it is there to mix up the fuel/air better for a cleaner burn at low rpms.

Since the throttle affects the actuators, there will definitely be a small delay between the TPS measuring the throttle, then sending the signal to the solenoid, then the vacuum being released to open the shutters. There is also that little delay valve which I assume keeps the spring from just slamming the butterflies open as soon as the vacuum is released.

All of that may not really add up to anything noticeable, but there is no argument that response will be quicker with the VTCS removed.

If I ever have the need to take off my intake manifold, I'll probably remove them along with the VICS.

The exhaust manifold leak is a distinct ticking sound and would sound much different than broken butterflies. I think I have a video of it posted on here somewhere.

 

[03.5rossman]

+1 thank you for the explanation.

I did however pull the intake manifold off yesterday and removed the shutters. After removing the shutters I tried starting and running the car and I still had the same problem. The rough "clack" and sound is coming from inside the exhaust manifold. Going to check the exhaust gasket and all the bolts on the manifold for tightness this weekend. After watching the video above, my car sounds almost exactly like that. Any other ideas are appreciated, thanks again.

 

[jdwk]

Then you most certainly have loose or broken manifold bolts. When I took my heatshield off for the first time, one was completely missing and another was all the way out but the shield kept it from falling to the ground.

Tightening down the bolts has been a 6 month ritual for me, much like re-greasing my sway bar bushings. Even after going to ARP studs (the single most overpriced item in the world), I still have to tighten them down about every 6 mos. I could probably tighten them past spec, but I think that is one of the contributing factors in cracked manifolds and I'd like to keep mine in tact. I also am avoiding loc-tite since if you ever remove them, it becomes nearly impossible to get them back in with that crap in the threads.

 

[Birdman_7]

Yeah that sounds like its the manifold bolts/leak, which would explain it going away after you drive for a while as metal expands with heat

 

[Jo060]

Mine has been ticking for about a year now upon warm up. I just let it happen haha.

 

[Cleverfrog]

Get some arp studs

 

[03.5rossman]

^probably will end up doing that, especially if any of them are showing wear or stripping. Beautiful build btw.