[rysbrnr]

I have a 2004 6i, auto trans, 68k miles. Recently it developed the infamous knocking sound that many 2.3L owners experience. This is hard to track down from what I've read on all the Mazda/Ford forums online.

When the engine is started cold, it SOMETIMES makes the knocking sound and if it does, its for maybe 2-3 seconds. Once oil is warmed up, it's barely audible at idle. If I free rev it (in PARK) it doesn't knock until 2500rpm or higher. I'm guessing it's coming from the valvetrain and hopefully not the bottom-end.

When driving, it only does it when as the RPM's climb towards 3000 RPM and when the revs drop during a gear change. When I'm cruising and speeds 30mph to 65mph it's SILENT

I pulled the valve cover and turned the crank 2 times CW and put a wrench on the intake cam. I followed what the service manual says about turning it back 90 degrees and listening for a knock in the VVT actuator. I did notice a small amount of play from within the VVT actuator gear.

Could all that noise be from the VVT? Yes one would think so, but I also noticed quite a bit of slack in the timing chain between the IN and EX cams too. So could it be a bad timing chain tensioner?

I'm sure someone on this forum has had to go through this before. I've searched all over with people saying they had this problem but haven't come across a DIY or write-up on how to troubleshoot this and repair it.

Any ideas would be very helpful to me and others who come across this in the future. Thanks

 

[rysbrnr]

I couldn't sit and wait for ideas from the forum so I went ahead and removed the oil pan. Rods 1 and 4 were a little loose.

Rod #4. I removed the rod caps and inspected the bearings on #4. The crank journal was still pretty smooth and so was the the big end of the rod. I couldn't hang a fingernail on there when I dragged my fingernail across each part. The bearing only spun a few times since I could still easily read the imprinted numbers on the bearing.

#1 was a bit worse. It was more loose than #4. When I removed the rod cap the bearing was scored up a bit which means it spun a lot more than the #4 did. The scoring was much worse on the bearing than on the crank journal and rod. I need to find an old copper penny so I can try out the "penny test" on #1. Regardless of what happens I'm going to take a chance and order a new standard sized and a "one step oversized" bearings for #1. I'll plastigauge both sized bearings and hope for the best fitment. I know this is NOT how it should be done and that I should pull the engine and rebuild it correctly but hey, it's worth $30 in parts to try it out. Worse case scenario is I have to buy a used short block or do a proper rebuild and throw it in... no biggie for me either way.

I've seen guys have rod bearings worn to paper thickness and they put in a new standard sized bearings and drove for over 15k miles before selling the car. There engines at idle speed sounded like a machine gun. My cars knocking was barely audible at idle and even while cruising so I'm going to {band-aid} fix it and see what happens.

If anyone is interested in this battle, please comment.

 

[rysbrnr]

In case I do have to rebuild this engine or replace it with a used engine.... Can I use a 2006 Ford Fusion longblock. There wasn't much info about this type of swap so any info will help. I read on Wikipedia that the Ford Duratec 2.3L is the Mazda MZR 2.3L and also has VVT. I noticed the Fusion uses individual Coil On Plug instead of a coil pack and plug wires but besides the external differences can I still use this motor? If the longblocks between the 06+ Fusion and my 04 Mazda 6i is the same, I'm going to go with this route instead of a rebuild.

There is a plethora of 06+ Ford Fusion 2.3L engines out there for a FRACTION of the cost of a used Mazda 6i engine. There's a 60k miles Fusion engine for $425 and a 12k miles engine for $800 within 25 minutes of my town. On the other hand there's a 101k Mazda 6i engine nearby for $1475!!!! and the next closest 6i engine is 3 hours away for $1800!

For my wallet's sake ,Someone please verify if I can use the 06+ Fusion 2.3l in my 2004 M6i!!! "Inquiring minds want to know!"

 

[broken08]

My bearings are spun too. what did you do?
Also, might oversized fit too tightly and not allow for oil movement? unless of course you actually grind down your journal. I'm trying to decide what to do on mine too. Mine spun at 53k

 

[slow6i]

if you buy "one step oversized" bearings, you will have to have your crank ground to fit them. .010 (the next oversize) is a lot in terms of oil clearance.

From the manual:

Standard Clearance: .019-.035mm (.0007-.0013")
Maximum clearnance: .10mm (.0039")

You need to mic your crank journals, or have them mic'd to decide on bearings.

 

[rysbrnr]

I ended up putting a new set of standard bearings on rod journal 1 and 4. replacing #1 bearing was no problem. The old bearing was just slightly scored up and the crank journal and big end of the rod was perfect. I installed the new bearing and checked it with plastigauge and it was right in the middle of the spec per the service manual.

#4 on the other hand was worse than #1. It the crank journal was slightly OOR out-of-round. I can't easily pull the crank for regrinding so I went ahead and put a new standard bearing in it anyways since I was in there already. The out of round specs measure almost exactly at the minumum and maximum oil clearance values. At its smallest plastigauge measurement it was .0010" and it's maximum measurement was .0037" So I felt pretty confident that it would at least work for a lil bit.

After installing the new bearings I checked for play in the connecting rods again....There was no movement at all and initially there was about 1/16" play in the #4 rod. So far so good. I put everything back together and fired it up. No knocking!

I let the car warm up and for for a spin. Now it's pretty quiet but it's still makes the exact same knocking sound only in certain conditions. When cruising 70mph it's silent, when accelerating it only SOMEtimes knocks. I've got a 1,000 miles on the new bearings.... no metal particles in the oil filter either. Is it rod knock again? I just want to know if it's the VVT actuator or tensioner or rod knock. I have no problem swapping engines or changing the VVT, but I don't want to waste time chancing the VVT or buying a new engine if it's not needed.

 

[rysbrnr]

I forgot to add that I also pulled the spark plug wire & injector plug of #4 and went for spin. The knocking sound was exactly the same as before. Conventional automotive wisdom says if you have suspected rod knock, you should disable the cylinder and the knock will be lessened or go away. This was not the case because at 2000-3000 rpm the knocking/rattling was still there. At idle it was silent.

I kept #4 disabled and did a free rev slowly from idle up to 3500rpm and got the same results as having all four cylinders running. At idle the knock/rattle comes and goes. As the revs climb from 750rpm it's quiet...then starting around 2000rpm the knock/rattle starts and get loudest around 2500rpm. By the time it's revving at 3500rpm the knocking is becomes intermittent..... which in my case sounds like a rattling heat shield rather than rod knock.

 

[broken08]

So everything you say here I may as well have said. EXACT same story. I just replaced my rod bearings since #4 definately spun, bad. Now that loud noise is gone but I still have the same intermittant ticking you speak of. We need to figure this out! Please update me if you find anything. I will do the same.

I'm guessing it's something with the VVT actuator. What do those cost?

 

[rysbrnr]

So everything you say here I may as well have said. EXACT same story. I just replaced my rod bearings since #4 definately spun, bad. Now that loud noise is gone but I still have the same intermittant ticking you speak of. We need to figure this out! Please update me if you find anything. I will do the same.

I'm guessing it's something with the VVT actuator. What do those cost?

Is your intermittent noise a ticking, knocking or rattling sound? Mine sounds very much like a rod knocking sound. I've heard other cars with a real rod knock sound and mine sounds just like it.... except those other cars knocked constantly at ANY rpm and at idle or light/heavy load. Mine doesn't really knock much at idle and when oil is cold it's completely silent.

My next test is to try stopping the VVT effect like another member here did. He said he put some kind of spacer or rubber spacer in between the vanes of the VVT actuator (effectively disabling VVT) to see if the noise goes away.

The problem is, how do you do that? Does the timing cover need to be removed or can you access enough of the VVT actuator to stuff the spacers in there?

Lemme know if you come up with any other ideas.

 

[Crimsonmt]

VTT system does make some noise atleast on my system. Another test you can do is when the car is running unplug the left green plug on the front of your motor. I dont have a pic but is right above your IM. See if the noise goes away. Once i do that all i can hear is the injectors and the slight timing chain noise

 

[rysbrnr]

VTT system does make some noise atleast on my system. Another test you can do is when the car is running unplug the left green plug on the front of your motor. I dont have a pic but is right above your IM. See if the noise goes away. Once i do that all i can hear is the injectors and the slight timing chain noise

I looked all over for a green plug on top of the intake manifold. Where exactly is it? Here's a pic of my engine.

 

[Crimsonmt]

sorry the plugs are green on my car:

 

[Mar Le Devine]

So have you guys had any improvement whatsoever? i'm dealing with the exact same problem and i'm both noob when it comes to car engines and i can't afford giving this to a mechanic. However, i really need to do it on my own as i have no other option.

 

[mv577]

Another NOOB here that would love to find out what the solution to this was... if at all...

I just bought an 04 6i with the 2.3... it was quiet when I bought it... after a botched valve cover gasket job by the used dealer and subsequently running it over 2 quarts down on oil it now has exactly the symptoms described in this thread...

Luckily for me the dealership has taken responsibility for it... but I'd still love to know your outcome...

Thanks!

Mike

 

[rysbrnr]

Another NOOB here that would love to find out what the solution to this was... if at all...

I just bought an 04 6i with the 2.3... it was quiet when I bought it... after a botched valve cover gasket job by the used dealer and subsequently running it over 2 quarts down on oil it now has exactly the symptoms described in this thread...

Luckily for me the dealership has taken responsibility for it... but I'd still love to know your outcome...

Thanks!

Mike

After months driving the car around AFTER I swapped in a set of new bearings on rods 1 and 4 it appears that I had TWO sounds producing the knocking/rattling sounds. It was the rod knock, and VVT actuator.

I decided to pull the front end of the engine apart and inspect the timing chain, tensioner and VVT actuator.

The chain tensioner seems to be extended all the way out indicating that the chain has stretched quite a bit but not enough to allow the chain to hit anything. There were no chain contact marks on the valve cover or anything else.

I re-timed everything (crank, cams) with the timing cover off. I noticed a clicking sound coming from the VVT as it went around. I took the 4 screws off the VVT to inspect and to watch what happens.

As I was manually turning the crank around, I see there's a small gap between the VVT's rotor vane and housing... Could this be the small gap that was giving me the knocking sound? I'm thinking yes. But if you look carefully you can see the "locking pin is not broken and it actually engaged. But what people say is that the hole that the locking pin engages becomes elongated... in this case it was elongated enough that it doesn't keep the rotor vane completely retracted... allowing it to be loose and "rattle" around as the engine runs.

This pic you can kind of see the locking pin is engaged.. I m' pointing to it with my pick tool.

To verify that it is bad VVT actuator I decide to insert a piece plastic and wedge it into the VVT and lock it in place. Of course I'm going to lose the VVT effect but it will be running like a non-VVT car.... so no ill effects.

Its just lightly tapped into place and it removable without taking off the timing cover, just yank the valve cover and remove the VVT screws and I can pull it out.

Results: The rattling sound from up top is gone! nice! But too bad the rod bearings on rod #4 are trashed again, as expected.
The crank journal and rod were unevenly worn as you can see in the pic. I verified this with green Plastigauge. The only way to fix this is to regrind the crank, get a new rod and get an undersized bearing. I have to pull the engine and tranny to do this. At this point it would be close to the same price as just putting in a late model Fusion engine.... which I've found on this forum to be pretty easy to do. I can get Fusion engines for under 800 bucks all day long. 13k miles for an 07 Fusion...only $700 bucks!.

 

[mv577]

Wow thank you for the response... great write up and pics... very helpful in understanding the issues people keep mentioning...

Could the elongated VVT pin hole be fixed? I imagine if it could you would have done it... what effects, if any, did you notice with the VVT disabled?

Thank you again,

Mike

 

[rysbrnr]

I suppose if someone really wanted to fix it they would have to weld in the elongated area and machine or file it down .. then re-drill the hole. I'm sure it would work...... Better yet, what I would do is not re-weld it in. I would drill the hole out LARGER and insert a hardened steel sleeve instead.. kind of like a heli coil but without the threads. I have access to a machine shop (my Uncle is a machinist) and I suppose he could make everything I need. Maybe I will experiment with this bad VVT and it it works, I'll put it in my new engine.

As far as adverse effects with the VVT disabled, I see none when it comes to regular daily driving. The VVT mode will only come on when certain conditions, (RPM, load, oil pressure/temp... etc.) are all met. I also have an Acura Integra GSR (DOHC VTEC) and I almost never go into "VTAAAAAAK Yo!" when I drive it normally. It comes at 5700 RPM (I think). When I go WOT into high RPM I feel no noticable difference in my Mazda 6 with the VVT disabled. I've put on 350 miles with my VVT disabled now. I'm going to run it this way until I get that new engine.

 

[kostika]

if you need any info about the swap you can contact me throw skype gedalia23 or throw email i will send you pictures of the set up just did the swap last week

 

[Nojodas67]

As far as adverse effects with the VVT disabled, I see none when it comes to regular daily driving. The VVT mode will only come on when certain conditions, (RPM, load, oil pressure/temp... etc.) are all met. I also have an Acura Integra GSR (DOHC VTEC) and I almost never go into "VTAAAAAAK Yo!" when I drive it normally. It comes at 5700 RPM (I think). When I go WOT into high RPM I feel no noticable difference in my Mazda 6 with the VVT disabled. I've put on 350 miles with my VVT disabled now. I'm going to run it this way until I get that new engine.

I too have a bad VVT actuator. Here's my post with picture: http://forum.mazda6club.com/2-3l-i-4/259053-normal-looking-vvt-actuator.html
Could you please share your experience with disabling your VVT and driving it for a while? I am set on disabling mine, but my only concern is for the ECM to throw a code and check engine light. Did you experience a CEL when you disabled the VVT. I would think that the ECM is able to monitor the angle with the use of the cam sensor.

 

[Final Impact]

Something that was not mentioned in this thread is what do these two failures have in common (bearings and VVT Rattle). The reciprocating components of the engine need clean oil all the time. There is no mention of checking oil pressure, checking the oil pump, or correcting the cause of why the bearings deteriorated so quickly.

Bearings wear as a result of recirculating dirty and contaminated oil mile after mile. Carbon from combustion is abrasive. If left in circulation it wears the engine at a fast rate. Because the bearings are soft and are MEANT to give their life to save the crank journals from damage, they are the first thing to go.

Should this event play out for any of you, replace the OIL PUMP while you're their!!! Change the oil often and connect a gauge in place of the factory oil sender and at least CHECK THE OIL PRESSURE! If it does not meet specification the event will repeat. Note: the VVT relies on the proper oil pressure to function. If it's not there - its going to rattle (baring it doesn't have a hard failure).