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Ah yes, another newbie with another broken MZ3

14K views 37 replies 7 participants last post by  Miljack 
#1 ·
So, I'm a newbie here despite having been signed up for...what, almost 9 years? Yikes...

2006 MZ3 hatchback manual. Around 70,xxx miles. We've owned it since 9000 miles. Has Mazdaspeed exhaust, replaced motor mounts some time ago, converted to spin on oil filter, but otherwise stock.

Hooned the car last night. Went drifting around in a gravel parking lot to prove to my wife that you cannot do any effective e-brake maneuvers with her car. You CAN however bang against the rev limiter for 20 seconds at full left hand crank with the car whipping around. Lots of fun, drove the block home with a clanging engine. :angry:

Doesn't appear to have a lose of power. Clanging is quiet at idle, louder and faster as the car revs. No CEL, no smoke, no overheating. Pulled coil pack connectors, 2-4 all dropped idle to a lop as expected, #1 made a worse clanging sound, clearly a #1 cylinder issue (I assume #1 is furthest passenger/left side, closest to the pulleys). Car still idled when 2-4 was removed, which I wouldn't expect if #1 was actually blowing air (bent valve, busted piston, etc). It's not a VVT type tapping sounds, we've had one of those intake butterfly/valve tapping issues for a year, this is clanging, engine internal type noise.

Wife drove to work today, other than the noise didn't report any change in drivability.

I will try to drive the car tonight and get Torque on the code reader for some info. This weekend will pull the plugs, check the oil, and dig around a bit.

What else to look for? Would a video help anyone give ideas? As much as it seems like valvetrain noise, I would expect either a CEL or drop in power or poor idle or something.


I am fully capable of digging into this engine and have most things needed for a full engine rebuild at my disposal right now.

Thanks all!
 
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#3 ·
That was one thought of mine, I don't know the oil paths well enough, but the #1 cylinder and valvetrain would have been on the oil rich side, not the starved side. Doesn't mean much, but it it was the opposite side of the engine that was my first thought. My other car is a dry sump, and doesn't seem to have those problems...
 
#5 ·
Well, a bit of driving and things have changed. The sound is all but gone when at idle or at constant velocity. Only with the most rapid acceleration of the engine does it come back. so, sedate driving is nearly silent, but fast revving makes a racket still.

The car needed a tune up anyways, so I have new plugs, filters, etc coming for this weekend. I'll get the inspection camera in the cylinder and look around as well.
 
#6 ·
So, she took it on the freeway tonight and got it moving, and the sound came back with a vengeance, but she drives the car hard. So, higher engine load and higher acceleration makes for more noise. as well, it threw a P0012 code.
I cleared the code with Torque and took it for a spin myself. Car is down on power, but smoothly, not from a missing cylinder. It revs, idles and runs like normal, just noisier and, oh, maybe 20% less power, especially above 4000rpm (car drives the same if you're sedate). I also learned that if I got it up to 35 in 3rd gear, it made noise, but if i then went of the gas the noise cut out instantly around 2000rpm and falling. I mean, like a switch was thrown, not getting quieter, just stopping. I also learned that it was at least a quart low of oil.

VVT? Sound is in the right location, loss of power at higher RPM would be from cam retarding, P0012 is a cam related code, I am sure that it is not a bent valve or rod or cracked piston, and there has been a ticking sound for a year now, I assumed it was one of the intake manifold vane thingies that have been discussed here, but it could have been the VVT clicking. Possibly I sheared the pin? I will try to examine the VVT assembly this weekend, and maybe make a shim to lock the, uh, gear things and see if that solves something.
 
#7 ·
Sounds like you oil starved a rob bearing and are getting some knock, especially since you said you just found out you were a quart low on oil while doing donuts at the rev limiter. Can you get a good video of the sound?
 
#8 ·
Wouldn't rod knock be low in the engine? This sounds high, and is a higher pitch, almost plastic-y vs. the hollow clang of mechanical knock. Also, like I said, when decelerating in gear under 2K rpm, it stops completely and instantly, which smacks of a control system, not a bearing problem. Do you agree?
 
#11 ·
Timing chain and sprockets are off. VVT on workbench. Looked at pistons, don't see any debris in the combustion chamber, nor contact damage on the piston head.
Chain had maybe 1/2 play between the gears. VVT...well, don't know how to determine if it's broken. I took the cover off, should I be able to move the two parts by hand? what actually holds the inner and outer pieces in some configuration until the oil control valve moves them? Is there a spring?

OCV appears to be fine.

Everything has a fine varnish on it, looks darker brown than most of the pictures/videos I've seen online.

New chain, sprockets, friction washers, VVT, and ANOTHER passenger side motor mount coming Tuesday.


Finally, the 2006 model doesn't show friction washers for the crank, but the 2007 model does. My car did NOT have any friction washers down there. Should I ASSUME that people are putting the 2007+ washers in the 2006- cars anyways for extra security? I ordered then anyways, but I bet they can be returned.
 
#13 ·
Well well well...

Removed the cam bearing caps and cams. Some minor scratching, but no radial scoring, no burn marks, no scrapes, no etching. There WAS powdered metal in the bearing cap oil channel, couldn't tell if it was ferrous, but it *looked* bright like aluminum.

Tested each tappet. Each spin with finger pressure. Each could be removed with 2 fingers and a rag. Each valve sounded good when struck with the mallet. Each tappet went back in without any drama EXCEPT ONE. It came out OK, but would not go in. Swap it with a different one, and the tappet goes into the new slot. The cylinder head itself is preventing any tappet from going back in. Now, it's so/close, but not working. I will probably lap the sides of the tappet against some emory to shrink it ever so slightly so it goes back in. Bad slot was the passenger side exhaust valve, cylinder #2.
 

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#14 ·
Now that the valves were all seated and the pistons had room, I proceeded to spin the crank several times by hand to check for interference, pressure, noise, etc. None was felt. Crank spun cleanly through many rotations, no scraping, no noise, no feelings, nada. Seemed really good.

Next was to check the pistons. Moved each to bottom location for best visibility, and put the borescope into each one. Cylinders 2-4 showed no signs of damage. Consistent color and structure to the carbon buildup on each. Cylinder walls were highly reflective.
Cylinder #1 was almost the same, except for 2 strange locations. Approximately 180 degrees apart, on the edge of the piston where the raised lip is, there was a section that was scraped clean, around about 30, maybe 40 degrees of the circumference. It looked like someone actually scraped all of the carbon off of there, but I couldn't tell if there was any indentation as well. The pictures show the borescope screen, those are two different locations even though they look almost identical. The cylinder wall is reflecting the surface, so it looked twice as thick. One was near the passenger side exhaust valve, the other was near the drivers side intake valve. I have never seen this structure before. No other marks anywhere else on the piston.


Otherwise, all parts arrived from Mazda.
 

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#15 ·
Finally, I need help with the following three things then (since some people will tl/dr my last 2 posts...)

#1: Tappet that won't go back in. Force it? Hammer it in? Lap it down just a bit? Try to scrape the cylinder head housing where it goes??

#2: Piston markings shown above. Not valve impacts, not anything like a foreign body, no structure damage seen, just weird areas stripped of carbon.

#3: For the life of me I cannot get the TDC pin in past the axle housing! It's so damned close, but it just won't go in. Moving the engine up and down doesn't help since the axle moves along with it. I will cut back the head a bit if no one gives me a better suggestion (I have the Lisle 37410 kit, http://www.amazon.com/Lisle-37410-Camshaft-Alignment-Kit/dp/B00DPWMYYU ). I bet I could take 1/2 inch off of the head and still have plenty to grab onto.
 
#16 ·
So you have 2 areas of cylinder wall scoring on #1 in two locations approximately 180° apart from each other? Sounds to me like that #1 piston was not travelling through the center of that cylinder for a short period of time.

Did you drop the oil pan and check the bearing journals on #1? That would be my next move, and if they look ok, I'd drop the crankshaft and inspect the rings on #1.

Or, you can get a junkyard low milage Ford Fusion 2.5l '10 to '14 non-hybrid long block and just do the swap. You already have all this time invested in this 2.3l trying to figure out what's wrong and by the time you figure it out you're likely to find out the cost of rebuilding the 2.3l after this failure will be only slightly less than doing the swap.
 
#17 ·
So you have 2 areas of cylinder wall scoring on #1 in two locations approximately 180° apart from each other? Sounds to me like that #1 piston was not travelling through the center of that cylinder for a short period of time.
No, not cylinder wall damage. The "damage" is all on the piston surface, but right along the ridge at the edge. The cylinder wall is simply a mirror finish and reflecting that damage. The other pistons had cylinders that had similar reflecting ability, so I think the mirror like finish is normal and acceptable.

Did you drop the oil pan and check the bearing journals on #1? That would be my next move, and if they look ok, I'd drop the crankshaft and inspect the rings on #1.
I ain't opening the block, it's not worth it. I have already gone further than I wanted to, but only because I saw that pulling the cams didn't require any unusual work (bearings, special tools, gaskets, etc). So far everything has been pretty simple, but the next step multiplies the annoyance and complexity several times, and it just ain't worth it for a 10 year old economy car.

Or, you can get a junkyard low milage Ford Fusion 2.5l '10 to '14 non-hybrid long block and just do the swap.
My wife is already looking at financing for a new Mercedes :eh: , neither of us is interested in dropping any more time or money into the car. If I get it buttoned up and it's still banging around, then we will sell it to some kid who is willing to do an engine swap.
 
#19 ·
I'd be interested in learning how that damage would occur. Is it possible that the piston tilted in the cylinder, such that the edge of the piston top was able to scrape against the cylinder wall, and yanked a slab of hardened carbon off the top surface? I would expect that a normal piston would regularly go slightly kinked from "true", but maybe this was more extreme?

Wrist pin...I can see that. If the pin or its bore was damaged, the piston would float more in the cylinder.
Rod bearings...I'm not sure sure. One, because all of the sound was high in the engine, two because I felt nothing when moving the crank back and forth quickly, and three because I don't think that a worn bearing would allow the piston to kink like that. A rod that was bent in a direction different than the crank might cause that...


Also, just for information, I'm *capable* of tearing this down more, I just don't *want* to. We planned on getting rid of the car later this year anyways. I rebuilt the engine in my vintage 911, I can do this one if needed. The only next step that I would consider is taking the pan off, dropping the rod caps and putting new, standard bearings in and bolting it back up. Not kosher I know, but reasonably fast, and might fix things a bit if the actual bearing is damaged.

Thanks for the helpful ideas shipo, SpecialEd and antics!
 
#20 ·
Also, just for information, I'm *capable* of tearing this down more, I just don't *want* to. We planned on getting rid of the car later this year anyways. I rebuilt the engine in my vintage 911, I can do this one if needed. The only next step that I would consider is taking the pan off, dropping the rod caps and putting new, standard bearings in and bolting it back up. Not kosher I know, but reasonably fast, and might fix things a bit if the actual bearing is damaged.

Thanks for the helpful ideas shipo, SpecialEd and antics!

If you want to try to get a good value for the car at resale, new bearings might eliminate the clanking noise for a test drive. This may or may not be the best "solution" and it's also kind of shady if you don't inform the prospective buyer of this repair.

I'm not a mechanic by any means and even though I work in a technical trade as my profession, swapping the engine in my 3 was and probably will be the most mechanical thing I've ever done or will do to any of my cars.

That being said, and looking back on it I think the engine swap was a piece of cake. It's a little car, has a little engine and simple systems to make it work. With the help from the step-by-step how-to's on the forums here I wouldn't hesitate to do it again if I had to.

The car I had before this was a 2004 Accord that jumped timing in the middle of a bitter cold Chicago February. I researched the repairs and costs, scoped the head and found that there was some upper end damage and after 200k+ miles the lower end was getting loose as well. That car had clear coat issue and the interior showed it's age... anyway I opted for a $500 band-aid fix and quick trade-in considering the cost of a full repair. If I had gone the full repair route on that car I'd have sunk in at least $3500 and I'd still have an ugly beater. The difference with the 3 is that it's a bit newer and in better shape and for less than $1k was able to do the full repair.

Your situation may be different and I get that. If you have the means to get a different car which would be less problematic or a better upgrade by all means that is the best option.
 
#22 ·
Also, before anyone brings it up...

Yes, I know that tossing new standard bearings on a spun rod is not the right solution. I know that the crank and rod both need to be machined, and oversized bearing put in. I know that the crank needs to be scanned for cracks and heat marks. I DON'T CARE. I want a rod that doesn't knock much for the next 3-4k miles and not much more. I understand the importance of keeping good engine building techniques front and center for others when they search.

I also know that sometimes, you can get away with scratches and gouges on the crank or cam surface under the bearings, because it just makes the oil journal bigger. I had a Toyota truck where I fixed a frozen camshaft with my DREMEL, grinding the damage away, then proceeded to off road it for 2 years, sell it, and had the buyer run it for 2 or 3 more years. I'll drop the rod caps, pull the bearings, spin the crank while scraping the bearing surface with emory until "clean", and button it back up.
 
#25 ·
Well, the rod bolts are NOT E10, they are E12. The cheap set of sockets I bought did not go to E12, so I did not pull the bearings yet :grrrrrr:
I did put the chain, guides, and sprockets back on.

I sanded the tappet down a bit, and it went in with some persuasion. I hope that getting beat like a mule by the cam teaches it some manners.
I cut half the head off of my TDC pin and it went in just fine, so now I can time everything.

So, I guess I order an E12 socket overnight from Amazon, and proceed with the timing, timing chain, lock down the cam bearings, put the valve cover back on place, passenger mount, wiring, then receive socket, do rod bearings, and be done with this.
 
#26 ·
Time to finish the story.

Finally got the E12 socket, and went to town on the rod bearings. #2 and #3 came off first because the engine was at TDC. First image shows the bearing caps and bearings. Some wear, nothing horrible. #2 bears had turned 90 degrees. No scoring on the crank. Replace the bearings, and turn the engine over for #1 and #4.

Well...#1 had been the source of my rod noise, and I think I found it. #4 bears had rotated 90 degrees and showed some scoring. #1 bearings...

well, I thought that it was missing at first. There was NO bearing under the rod cap. None. Nada. There WAS however TWO bearings under the rod surface, because the one had gone UNDER the other one. That's a new one for me! The bearings had been hammered paper thin and were split and torn/missing sections. However, the crank and rod cap didn't look that bad, so I tossed new bearings in and buttoned it up.

Timing cover back on, oil pan back on, valve cover back on, everything put together. Cranked for a few seconds with the fuel pump fuse removed to build oil pressure, then powered the pump a few times, and the engine fired right up. Load dependent ticking from the top of the engine still (only when driving, not just revving), but no rod noise. Drove around including highway speeds and RPMs up to 5K, no loss of power and no codes. No oil leaks, no overheating, just some top end noise.

Told the wife to turn the radio up and ignore the sounds, drive like the car is 100% fixed because it's silly to be afraid of it or baby it at this point. If the bearings blow out again, she should drag it home screaming instead of having it towed, because the engine is of no recoverable value right now, and a blown rod won't affect any of the rest of the car that is in excellent shape.

Maybe I'll get a video this week of the top end noise while driving. It sounds like what we've had for almost 2 years (but slightly louder), which is a load and speed dependent, plasticy clicking-tapping sound from the top end.
 

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#28 ·
Awesome of you to post a follow up. Let us know if you have another (presumed) bearing failure if you don't mind. I'm sure I'm not the only one here that is curious how long this will last.

After seeing those scope pics of the clean metal edge on #1 I was almost certain it was rod bearings or wrist pin. That piston head will rattle around in that cylinder when those go out of spec and cause quite a bit of damage to anything near them.

Funny though I've never heard of bearings worn so thin they rotate atop each other before, crazy.

Wonder if that top end noise is the VVT noise that others have experienced? I've never heard it in person or had to deal with it but a google search will lead to a few good videos of that issue in action.

Keep an eye on those oil levels too. I know you're not hell bent on keeping this car for the long haul but seizing the engine due to oil starvation leaves you stranded on the road and that always sucks.
 
#29 ·
Funny though I've never heard of bearings worn so thin they rotate atop each other before, crazy.
Not saying I've seen that happen a lot, but I have seen it several times; said another way, it is more common than you think. That said, I have *NEVER* seen the spun two-layer bearing thing happen and leave the rod end relatively unscathed, so this is a first for me too. :)
 
#34 ·
So here we are, 3 years later.

I've been driving the Mazda daily for these three years, ignoring the various noises. No significant oil loss, down about 20% on power overall, but otherwise 3 years of driving.
Until a few weeks ago, when it went from fine to OMG over about 5 miles. I was able to get it home, but it's clear that either the wrist pin finally cracked, or the piston cracked, or it impacted a valve or something. Top end, nearly catastrophic damage. I will say that one diagnosis that I tried was interesting. Pulling power to the #1 coil made the noise MUCH worse and MUCH more metallic. I wonder if the piston was floating somewhat freely, and the pressure of detonation was keeping it somewhat stable. Remove the spark leads to removing the detonation leads to removing the pressure against the piston surface at TDC leads to something banging around more freely...

So...I bought a 2011 Ford Escape 2.5L engine and I'm halfway through the swap. :)

I've been driving the car instead of my vintage Porsche because it's surviving day to day driving better, the wife ended up buying a Subaru. We kept the Mazda because it had no trade in value, even though it is in really great shape other than the engine. So, give me 2 more weekends and you'll have another member of the 2.3L to 2.5L swap club!
 
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