Engine Noise, Vibrating Clutch, ect!!!
 

Hey guys,
New to this forum, but I have an issue with my 2007 Mazdaspeed3! I have been reading threads on here for the last couple days, and haven't quite found the info Im after. Please forgive me if Ive overlooked something.

I recently replaced my rmm (Cobb) and changed the spark plugs. After very little driving I am noticing a vibration at the top of the clutch, about the first inch or so. It runs great, but after its warm and the car is idling the engine makes a noise, maybe like a light knocking. But it goes silent when I fully depress the clutch pedal.

So.. Im hoping that I don't have a bent rod!! Im thinking that isn't the issue, because I wouldn't think that the sound would ever go away if it were??! Maybe a tob, clutch??
Any help would be awesome!!
Thanks!!

Sounds like something in the clutch if the noise goes away when depressed. Bent rod will make your clutch feel like it has ABS just when you barely touch it, but the clicking noise won't go away. You can always do a compression test or measure how close you pistons come at top dead center....

Thanks!

I just did a compression test

#1-157
#2-165
#3-165
#4 -155

Also noticed #4 spark plug was a lot richer than the others, After only about 100 miles.

What was the fourth compression number?

sent while Netflixing...

cylinder 4 was 155psi

100% bent rods

Yup, pull the plugs and insert a rod so that you can measure the heights of the pistons at TDC. One or more will measure shorter, dat is your bent rod.

Was this compression with motor hot or cold?
Does the pedal vibrate or pulsate?
Is it chattering sound that goes away compleatly when pedal depressed?

A new rmm will make more vibes.... some vibes in pedal is normal, but a pulsating feeling means a bent rod... The chattering could very well be the throw out bearing which is VERY loud in our cars. As for the comp numbers if this is a cold motor then its not totaly bad, low yes but not catastrophic.

I appreciate the replies. A little more info though, I notice this issue right after letting a friend borrow the car for a day, (an older guy, who might not have been great at using the clutch, even though he assured me he was!)

And again, I'm am struggling to see how it could be a bent rod if the engine sounds fine, no knock, no vibes with the clutch fully depressed?! Im hoping that its not a rod!
Also I would describe it as a pulse kind of like an abs feel.

These cars are noisy bastards. I thougt shit was broke after my rmm. I do get vibs on the engagement area of the pedal. It is said a true bent rod will be known without a doubt in the pedal. Like some sort of un-earthly feeling.

Warning: over tightening the rmm results in more vibs.

Was that compression on a cold engine or was it warmed up? Makes a difference. If you ran it with the engine cold, rerun the test after letting the engine get up to operating temp. Take all plugs out and hold your gas pedal down when testing, as that cuts off fuel flow to the cylinder which affects pressure and dilutes your oil.

Be sure to keep the starter going until you reach max pressure on each cylinder. When the needle stops moving, then stop. It might take as many 10 -12 compression strokes to max out.

I would say your compression looks low across the board, not really that bad a difference across cylinders. Measure the distance across all 4 at TDC will tell you for sure.

Mine vibrated like ABS when I rested my foot gently on the clutch, and made noise no matter what I did. Tried to convince myself it wasn't and just the noisy MS3, but I have the pictures to show otherwise.

Good luck, sounds like the measurement of the piston height may hopefully give you peace of mind you're ok