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My 2007 (1st gen) Mazdaspeed 3 suffered the dreaded VVT (variable valve timing) failure that continues to plague MZR 2.3L DISI engines (both turbo and naturally aspirated) across the world. Mazda issued a warranty extension program to fix this issue for free but I just barely missed the window of opportunity so I fixed it myself over a long weekend (and I mean loooooong).
This video shows me setting the chain tension by loosening both the intake (VVT) and exhaust cams, then pulling the pin on the chain tensioner and cycling the chain through a couple rotations. What I FORGOT to do in this video (that I did later) was to push the chain tensioner arm away from the tensioner, as this will cause the tensioner to click out another stop or 2. You need to do this with the cams loose so that you can cycle the chain a few times and re-even out the tension. I did this AFTER tightening the cams and it created very uneven chain tension so I had to loosen the cams and do it again.
- Quoted parts & labor repair cost from the dealership: $1300-1400 (over $900 in labor)
- What I paid in tools & parts to DIY: $500 ($300 parts + $200 tools) + 3 days of my life
- I spend a borderline absurd amount of time preparing for this job all to save less than $1k but you can't really put a price tag on how much I learned about this engine and cars in general. I also feel much better about spending my time and accomplishing something of this magnitude than just throwing $900 in the garbage and learning nothing.
I extend a HUGE thank you to the MazdaspeedForums.org community for providing troves of information, lending me tools, and even helping me wrench for 12+ hours (IOU1 Patty-Wack). I absolutely could not have done this without the phenomenal resources that MSF provided.
Check out my write-up notes on this procedure in the giant "How-To VVT" thread on MSF:
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If anybody has made it this far into the description, here are some tips if you're looking to do this yourself:
- Get the Factory Service Manual and USE it. Follow the methods and torque specs in there and most of this procedure is quite straight-forward. The initial tear down is most of what you have to make up yourself (i.e. there's no how-to for detaching the wiring harness).
- Get a pneumatic impact gun. I only used this to get the crankshaft bolt off (having my friend put the car in 6th and stand on the brake pedal) but I returned it afterwards to Harbor Freight for a full refund.
- Get the REAL SST's for the cam alignment plate and the TDC pin. I also had a set of knock-offs and they set a bad TDC and the CAP was bent (it was just a waterjetted plate instead of machined SS).
- Get a 10mm 6-point box wrench (NOT a 12-point) to get off the idler & water pump pulley bolts. My 12-pt started to round the idler pulley bolt and there wasn't enough room to get a socket wrench on it until we removed the PMM and jacked up the engine (but even then only one specific socket wrench fit, a 1/4"-drive Husky).
- Remove the HPFP & housing as one unit to avoid having to deal with the weird E8 inverted torx bolts on the fuel pump, itself.
- Loosen BOTH the VVT & exhaust cam sprockets when setting the chain tension so that it will even itself out as you spin it through a few cycles. Also push the left chain guide towards the chain to make sure the tensioner is fully clicked out (mine clicked out another notch after I had tightened the cam sprockets, creating uneven tension in the timing chain, so I had to loosen the sprockets and do it again).
- Get a universal pulley holder ($60 from Amazon, which I also returned) to hold the crank pulley when you're torquing the crank bolt to avoid bending the TDC pin or shearing the M6 bolt holding the pulley to the timing cover. I had the handle wedged up against the upper control arm bolt with a 2x4 between them.
- Get some ARP Ultra Torque thread lube and smear that on the crank bolt threads and head when installing the new bolt. This bolt eats up almost 300 ft-lbs WITH lube and who knows how much without it.
- Organize bolts from each part into ziplocs and label them for ease of reassembly.
- Convince somebody to help you for both mechanical and emotional support. This job takes a long, long, long time and makes you go a bit crazy.