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Discussion Starter #1
Hi, my name is Tim and I just joined this forum on the Ford Focus. I love my 05 ZX4 ST that I just bought, but it seems to have an annoying engine noise that I would really like to take care of quickly. I suspect the timing chain and associated components and would like to know if anybody could confirm what's going on. At around 25 to 2800 rpm the engine makes a very noticeable knocking sound at neutral throttle. If I am accelerating or decelerating there is no noise, but again if I am just rolling down the highway at partial throttle, just enough to maintain my speed, the noise is there. The car currently has 125K on the odometer and is generally in very good shape. This is a really fun car that I would like to hold onto and I would appreciate any advice from the experienced owners out there. Thank you.
 

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Can't help I'm afraid, as described that doesn't match the common "tumble flap" ticking when they're worn that's often confused with valve train or injector noises.
 

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Discussion Starter #3
Thanks sailor. I have heard that the timing chain can stretch sometimes beyond where the tensioner is no longer doing the job. That's was what seemed to make sense to me with the rpm and throttle. A local mechanic told me it could be piston slap and that Fords are nototious for that. The thing is, is that I thought piston slap would go away or get less as the engine warmed up. It actually seems to get a little worse. Thanks for responding.
 

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It's a possibility, don't see it happen often. (cam chain tensioner, not the piston slap)

If it was cranked over slowly by hand, with the plugs out, you should be able to see one cam through the oil fill hole NOT move smoothly all the time if the chain was loose.
 

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Discussion Starter #5
That's a good idea sailor. I suppose I could just take the valve cover off and check for slack on the chain. Thanks for the tumbler flap idea also. There seems to be a lot of discussion about that. Doesn't hurt to check it out. Is piston slap common for this engine at 125K? So being new to this forum, do I just click "quick reply" or do I "post reply" to get everybody's view point? Thanks again.
 

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You should be able to see well enough through the oil fill to watch for a cam to "jump" as the valve springs move it IF the chain was loose. Haven't heard of piston slap yet on a duratec. Rod knock is the worry as they wear out, with keeping good oil & filled up the only preventatives. There have been one or two with stretched chains/tensioner troubles I've seen posted.

Quick reply gives you the basic tools for posting a reply, post reply or "go advanced" at the bottom take you to another box with more tools for making up your post.
 

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Discussion Starter #8
Well, the cam chain seems okay. The sound seems to be getting worse. I guess its either a rod bearing or piston slap. Probably an engine swap is the best solution. Is the 2.3L in my ST the same as the 2.3L used in the Mazda 3/6 or the Ford fusion? I'm thinking of getting a used engine at the bone yard.
 

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Mazda motor is almost the same, the fusion while it all looks the same, throttle body and intake issues. Focus and escape are your easy button answers.
 

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Discussion Starter #10
Interesting. The 2.3l escape will be a direct replacement? Any minor finessing I need to do to make it work? Thank you for your help.
 

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Before you do anything, Unplug the vacuum line going into the i/m to the solinold on the passenger side & start it up & listen. What your doing is cutting the vacuum to the tumble flap solinold & they'd be in the open position. Low oil is a more common cause of taking out the rod bearings. A great/cheap mod that I recommend is removing the balance shafts (5 bolts) & its in your hand & put a plug in the oil feed hole, really easy & holds 6qtrs of oil & frees up the motor.
 

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Have you probed for the source of the sound? Use a screwdriver or wooden dowel, sit it on the potential part that you think is causing the problem, for example the engine block, and see if the sound is loud or muted. Definitely check the intake as that is the cause of the tumble flap sound, and although you refer to this as more of a knock than a tap- I do recall my early tumble flap sound as being deeper.

It could also be the balance shaft that is knocking, not the rods or pistons. That part can be removed for a boost in power, and some minor engine shaking. We've also heard, many times, of knocks that ended up being bad motor mounts instead of internal engine issues.

I'm not trying to insult your engine know-how, but I've had friends who were accomplished hot rodders who thought that a loose bracket was a valve train sound until we started probing the engine for the source.

It's certainly easier and less time consuming than an engine replacement, and if you only verify your engine is knocking, then you've only wasted a little time. If I were to find an engine knock, I'd definitely consider purchasing an inexpensive balance shaft delete kit first before complete engine displacement. Balance shafts spin at 4x engine speed, so those bearings will go out before others. If you go removing the shaft, there is a procedure, follow it carefully.
 

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Diag the noise first before you start a motor replacement, most items in the 2.3 can be repaired, replaced or modified much easier than a motor swap. As stated look for the simple repair first, always as these motors normally are very robust and good for many more miles than yours have.
 

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Discussion Starter #14
Thanks guys. This is my first exposure to these engines and I am just starting to learn about them. I truly appreciate your insight and thank you for helping me avoid wasted time and money. I'll let you know what I find.
 

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IMO, the #1 suspect would be the front engine mount on the passenger side of the engine compartment. This one is hydraulic filled from the factory, and is known to leak after about 100k miles. Age wise, if the rear (also called transmission mount) has not been changed, then it is suspect. You'll have to remove the battery and battery tray to get to it. Damage should be visible on this mount- rotten and cracked rubber as it's just a big rubber pad. The front mount has a hydraulic filled chamber that sort of looks like a rubber donut. If it is not firm, it is bad. There is a 3rd lower center mount called the dogbone mount, or proper term= torque strut mount. If you change the other 2, then you should change this one also whether it looks good or bad. There is a proper procedure, and we highly recommend purchasing the Motorcraft part for the front engine mount if you aren't going polyurethane race only mounts that turn your car into a magic finger massage machine at stoplights. The other 2 mounts are ok to purchase Anchor parts- the only aftermarket OEM style mount manufacturer. I suggest Rock Auto for those.
 

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Discussion Starter #16
Is there a way to attach a video so you can see and hear the sound? I did a little exploratory search for the noise and it kind of sounds like the top end at the exhaust cam. I would think if it was a motor mount, given the sound that it makes, that engine movement would be visible. Not sure though. Thank you
 

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Discussion Starter #17
Well, mystery solved. Definitely a rod bearing. Dropped the oil pan, took #1 rod cap off and its hammered. Miraculously, the crankshaft look okay. Mic's out to spec. Do you guys know what the toque is for the rod bearing caps and for the bolts that hold the balance shaft assembly on to the block? Can't find it in my manual. Thank you
 

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Well, mystery solved. Definitely a rod bearing. Dropped the oil pan, took #1 rod cap off and its hammered. Miraculously, the crankshaft look okay. Mic's out to spec. Do you guys know what the toque is for the rod bearing caps and for the bolts that hold the balance shaft assembly on to the block? Can't find it in my manual. Thank you
Since your doing rod bearings & have the bs off, I'd leave it off & plug the bs oil feed hole. There are kits (plugs) to do that. That'll also add a qtr of oil & free up the motor. Sounds like you ran low on oil. Massive performance, central Florida motorsports, fwerk's, Steeda sell bsd kits.
 

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Discussion Starter #19
I have heard good and not so good about the bs delete. This is my daily driver and it seems like deleting the bs will just add vibration to my drive without any meaningful performance gains. I suppose I could just try it out. Do you know anything about the torque spec's for the rod bearing caps and to reattach the bs? Thank you
 

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I have heard good and not so good about the bs delete. This is my daily driver and it seems like deleting the bs will just add vibration to my drive without any meaningful performance gains. I suppose I could just try it out. Do you know anything about the torque spec's for the rod bearing caps and to reattach the bs? Thank you

As said above, it will free up a quart of oil to better lube bearing that are being used, the Duratec engines (almost all of them), have problems with lubrication to the rod bearings, some say it's do to the engines not having enough oil and people "over fill" it a quart on purpose. I can't say for sure because I have never owned one. But the 2.5 and 3.0 v6 engines had the same problem
 
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