Startup noise (most likely not VVT)

Hello there,

History of the car:
Previous owner of my speed was a Mazda Mechanic. He bought the car in '13 with 158t KM (98t miles) and engine failure (seller tried to change the timing chain). He rebuild the motor (according to the service history new pistons, rods, timing chain, oilpump, clutch...)
I bought the car in early '19 with 164t KM (102t miles)
Now the car has 195t KM (121t miles) and 3t KM (2t miles) ago I changed the accessory belt with tensioner and idler.

Problem:
Last week after work, the car had a ticking/ ratteling noise at startup. I imediately thought of the VVT actuator..
On my way home I had to do two stops (5-15min) and at both starts the noise was there again.
The noise was just around 1 second and I'm 99% sure it did not come from the cabin..
Otherwise the car is fine, never rattles, power is there, fuel economy at 9.5-10l/100km (~24mpg)

What I've checked:
I removed the valve cover. At TDC there is no slack, I can push the chain 1 or 2mm (0,05inches)
VVT actuator has Revision C, so it should be fine??!!
The notches in the VVT actuator align as well.
I removed the accessory belt and checked all wheels for play -> found nothing
I checked under the car for any loose bolts / sheetmetal -> found nothing

My problem now is, something did make the noise, timing chain & accessory belt seem to be fine, nothing is loose, but there was a noise. Does someone have an Idea what I could check?

Thanks, Andy

 

When you checked timing chain tension was the engine at TDC? You be nice a snug when at TDC. Any marks on the underside of the valve cover when you took it off?

 

I edited the original post with a video of the chain at TDC. It has no slack, but I can push it a bit. The valve cover has marks in it, but the chain has already be done, so I asume they are from back then, they do not look new I suppose..

 

Is it ok for the chain not to be snug if the engine is not at TDC? (and if so, why?)
After driving yesterday I checked the slack through the oil filler neck and there is slack (no idea where the engine is at..). Could the chain be bad although the VVT is fine (according TSB_01-012-12)?

 

Did you inspect the locking pin when you had the vc removed? It's very hard to see in your photo, but it almost looks like it's broken (cap is missing).

 

Jup, I did, but I think it looks as it shoult? (Picture is a bit blurry )

 

No worries, that shows it perfectly. That's in perfect condition, that actuator is good.

 

Finally an update or rather the solution to my problem

Because it sounded like chain and the chain was looser than I would think it should be, I ordered a complete chain kit.

During disassembly I noticed, it really was a bad VVT actuator. Although it was not completely bad. It would latch, but with enough force I was able to unlatch it. That is most likely the reason why it seemed good during the test according to the TSB but not good during engine start.
What I noticed as well was, that the last guy who was in there, damaged the oil pump sprocket and instead of getting a new one, he glued it in with green Loctite. So I ordered a new oil pump and sprocket and waited further..

Now everything is back together, multiple starts and ~100km driven..

Bonus pic of the actuator, the groove should not be there Interesting is, the groove is not all the way to the bottom of the bore, that is most likely where the pin would hang on...

 

Well that would certainly don't, glad you figured it out and she's running well.

 

I haven’t watched this video recently but my recollection is that it gives a decent explanation of what’s going on.

 

UPDATE!!! So here's one that can show and tell l you exactly what your asking about better than I can. His YouTube Channel is "Speed Car 99". And add vvt which is nearly identical to vvt but worded by VW. He makes it clear as to what your hearing and why you hear what you do for but a few seconds of a cold startup. But this is only if your actually able to correctly identify the sounds pertaining to your issue. But I've searched and see thousands upon thousands of people have had to deal with this noise along with others connected to the timing chain kit. And for further insight YouTube Channel "I do Cars" and add whatever vehicle you may be requesting along with the title or name and he will show and tell you while breaking down these engines in particular which he's done near 60 and has seen the same things that condemn these engines. Thought I'd share this with you being I've been up all night trying to figure this noise out without throwing parts at this car. The internals on my engine are very nice after having been oil/filter changed in less than 2,000mi. But it's hard to determine the VVT itself unless you take apart, breakdown and at that point you may as well replace also. But just to confirm rather keep breaking down just to keep having the same issue arise. slSo now I feel much better considering I knew it couldn't have been the timing chain kit. So upon replacement of the VVT I will let you know how things went. And also I found there was recalls on the factory VVT due to Mazda not having them heat treated so that they would stand up to the brutal work that they are required to do therefore leaving them more apt to fail which has been one of the many issues with this engine if not just plane ole neglect. Until then, take care n b safe!!

 

One other thing so that you know something tried and true. Depending if you know how your engine has been treated for whatever miles it has, you can make an educated guess as to what viscosity to put into the system. I know for a fact any engine running in the city will break down an oils viscosity sooner than one that is driven in less constant stop and go scenarios or in less restricted areas to drive without stopping. So I'd say even at your first timing chain kit replacement you may want to consider stepping up the viscosity of your engine oil to prevent it from premature wear. Which will likely occur if you keep treating it as though it were still new. But 60,000mi. I'd step it up beyond 5-20w to 10-30w and as you accumulate more miles on the same with your viscosity. I run 15-40w semi synthetic blend with no problems at all. But upon the oil change being it's been near free there I also ad the 5-20 to ensure the oil pump isn't strained and that all oil galleries will feed wherever as supposed to. And trust me, the car runs near new being it the tolerances are no were near new and your merely filling in where metal has been lost from use as it normally would. Many don't know these things and wonder why they have rod knocks to oil leaks and so forth because running water like oil in a used engine with or without turbo will only prematurely wear the engine out. Check out "I do cars" and he'll explain why I do this. My engine doesn't smoke, use oil, and is sensitive to the touch of the throttle despite the VVT needing replacement. I can only imagine how much more better it's going to run once I put the new one on there!! I like bringing older cars back to life and rejuvenating them. Just a tip and if your hesitant to try it then by all means don't. I'm just an auto tech and not a doctor so what do I know!! Take care