Rattling DOHC

[34Ford]

Anyone have any ideas why my new Mach 1 has a rattling when its not up to temp right at the moment you dont have any load on it?
Ya know, the point where your not accelerating and not coasting.

It quites down once it gets upto temp. Its so noticable even my wife asked what it was.:eek:

It has done this from the get go. Not sure if its getting worse. Dont drive it very often. I am going to have the p/s pump replaced thursday, and Im taking the mechanic for a ride so he can listen, but Im not sue he has any dohc background.

Dennis

[ausie]

I believe that has something to do with the timing chain tensioner which is controlled by oil pressure from the heads. As the RPM increase, so does the oil pressure which places tension on the tensioner. I have that same noise but it goes away after the temp is at normal. I did not notice this until I changed to synthetic oils. When the car sits for a while, is when I notice it. If you use the recommended oil viscosity that should clear it up, right now I am running AMSOIL 20W50 oil. Even though the the numbers are high, it is a relatively thin oil. You may have a varnish build up on some of the parts. At your next oil change interval, get some B-12 Chemtool and put the recommeded amount in the motor oil (only do this if the motor is cool otherwise it will evaporate) run the motor 5 to 15 minutes at idle and then change the oil. B-12 Chemtool does a good job at cleaning parts and it does not take long for it to evaporate so it will not be left in the motor when you drain out the oil like some other products that are mainly kerosine. I hope this helps or fixes your noise.
One of these days I will be taking the valve covers off to inspect the lifters, etc. also I want to see if I can fix the baffles or add baffles to the PVC port and the breather side since I keep sucking oil into the intake.

[34Ford]

ausie,

First and foremost I want to thank you for replying. I had given up on any replies, figured the Cobra people were used to the rattle or it was my motor.

You have a interesting point too. I have never heard anyone say it was the tensioners. Over on the mach1registry their saying its piston slap.
All I know is since the weather has warmed up its not as noticable, but none the less, its still doing it.
I have been using Motorcrafts 5w20 synthetic-blend for oil. Ill will keep this in mind. I had hoped to drive another DOHC someday just to see if its normal.

Dennis

[Jesse99]

That sound isn't normal.. If your car is still under warrenty I would take it in.. If not you may consider changing your oil.. I've heard that some oil causes the engine to knock at start up..

[ausie]

I can agree with Jesse99 that the sound is not normal. I did not have it until I switched over to mobil 1 on the sencond oil change, one reason I will no longer use it. Ever since then there is an occasional rattle when the car is cold. I had been told it may be the timing chain tensioner (there was a report why ford went to a light weight oil which was for that purpose).

I also noticed that I get noise from the throw out bearing in the clutch but that is a different sound. The rattle sound usually goes away after driving a few miles, most of the time I do not hear it expecially when it is hot outside. I have also noticed that the rattle is more apparent when I have hit 2000 miles after an oil change.

My car uses oil considerably. I had that checked out and there is nothing mechanically wrong with the pistons. I tracked the oil consumption down to the PVC valve where under hard acceleration oil is passing through the valve into the intake which would explain all the varnish in the intake. I attempted to reduce the oil consumption by using two breather filters on each head. The result was oil every where. After noticing that, I did some searching and made a note in one of the forums, I got a few replies about the valve cover baffles being insufficient which allows oil splatter to be sucked into the intake.

I have two options, one is to have Ford add baffles or replace the valve covers (I do not want that, I would hate to loose the signature plate). There is a product called a PVC catch can. I can list the link in another post.

As for the noise, I would definately get it checked out. Also check your oil level with the motor cold. If it is low, then you may have inherited the same baffle issue that the 01 Cobra has. If you did, what comes next? massive carbon build up in the combustion chamber due to the small ammounts of oil being transfered throught the PVC. It may even increase your compression a bit, but the worse thing that will happen is the motor will start to ping and possibly suffer from detonation from the hot spots on the pistons, plugs or valves (carbon retains heat which casues the hot spots).

I lost faith in Ford since they came back to me and said there is nothing wrong with my Cobra, but what they did notice is not excessive. Perhaps I do not drive the car hard enought to prevent the pining, etc.... I replied back to them that I drive the car like I stole it almost every time. Which is almost true. The problem is the harder I drive the car, the quicker the oil disappears. Believe me, there is alot of oil pressure in the heads, even at idle there is alot of oil spray that will come out of the filler cap if it is off. Which explains why the two oil breather filters became saturated with oil in a short time. Sure, the car ran better without the PVC system connected (blocked off with vaccum plugs - not street legal) but it also made the engine bay on the dirty side.

When I install the PVC catch can, I may add a breather filter on the other valve cover (passenger side) since oil gets sucked in at both ends. I may take both valve covers off to see what can be done with the baffles. Actually, I may remove the bung on the intake and put another PVC valve there to prevent reverse flow. Which I may try that first.

[ausie]

Here is the link to the PVC catch cans. I think I got this from Firme some time ago (not really sure if I got this link from in here or not)

http://www.accmachtech.com/pcvcatchcans.htm

[34Ford]

My dealer already knows about the rattle, in fact I took the mechanic for a ride and he agreed. They just said for me to monitor it.
In other words these dumb a$$es are not SVT approved and know nothing about DOHC's.
So Ill keep driving it. Probably just a matter of time before I get the dreaded "tick" anyway.

[Jesse99]

My dealer already knows about the rattle, in fact I took the mechanic for a ride and he agreed. They just said for me to monitor it.
In other words these dumb a$$es are not SVT approved and know nothing about DOHC's.
So Ill keep driving it. Probably just a matter of time before I get the dreaded "tick" anyway.
Sounds to me that there too lazy.. I would try to take it to another dealer and tell them what your dealer said.. No dealer should tell you to monitor it.. The problem could be under warrenty, but if your blow you engine the other parts might not be covered..

[1-QIK-SNK]

I had that same problem on my 96. I was using 10w30 valvoline, but switched to 5w30 Mobil 1 synthetic and have not herd the rattle for about 2 yrs now(knock on wood).
Now I will go and start it up and probably hear it.
Good luck.
Kerry M.

[NO 5 OH]

Man I need to come in this section more often ;)

Dennis, the problem you're encountering is more than likely "piston slap" when you first start the car. The pistons that Ford puts in the mod motors are teflon lined, and when the teflon wears off the sides of the piston then you get piston slap. This is because when assembled, the tolerances that Ford has are so tight (.001 or less :eek:) that any extra room in the cylinder wall will cause the noise until the motor warms up and the pistons somewhat "expand" to fill the room... for lack of a better way of putting it.

My 01 Convertible did this, as my new 03 does it as well. The chain tensioner is also another possibility... but I'd bet odds are it's the piston slapping the cylinder walls. The sad part about all this is Ford really won't fix the problem right... as the only way to properly fix it is rebore the block and fit it with a good quality aftermarket piston. This of course is expensive.

If you're running something heavier than 5w-20, then switching back to that type will possilby help... but won't get rid of it all together. Your best bet (although I don't like it either) is just live with it and let it warm up thoroughly before hammering the gas.

HTH,

Shannon

[34Ford]

Goodness. Thanks for the replies. This thread was pretty much gone from the git-go.

Shannon,

You have pretty much summed up what they said over on the registry, and for the most part their living with it.

Like I said, I use the Motorcraft 5w20 synthetic blend and I do the changing myself.

And I do let the motor warm up when I can, or I do not romp on it till its up to temp.
Back when I originally posted this there was no discussion on it, then I saw other people over on the registry finally bring it up and some took their Machs to the dealers, and they basically said live with it.

So hell, let'er rattle.

I wonder if my aluminum block and 10:1 compression will also contribute to how loud it is compared to the Cobras iron block?

Dennis

[ausie]

I find that very hard to believe. Can you supply a link to that? I heard of some funny stories, but that one is too deep for me. :D It could very well be the hot glue they used to mount the piston rings. And don't forget the rubber bands that are used as "o" rings on the crank. There is one story I do recall, was that ford installed some over sized bearings on some cobras which caused engine knock.

Perhaps the noise you experience is far different than what I get once in a while. Besides that, if the piston were to loosen up to the degree it begins to rattle in the bore, you would also be burning oil along with the rest of the motor. It may however, be related to piston rings, more than the piston itself.

The noise I have experienced it in the valve train and more than likely the timing chain. And some of the noise is from the throw out bearing in the clutch.

I am still laughing about the teflon coating. If true, then Fix Or Repair Daily may be an understatement.

[34Ford]

Here is a couple of threads on this.
They say there is a discussion over on Stangnet as well.

Clicky here (http://www.mach1registry.org/forums/showthread.php?threadid=12903)

Clicky here (http://www.mach1registry.org/forums/showthread.php?threadid=12781)

And there is a ton of talk about the dreaded mod tick

I finally fixed the problem of the hanhing rpms, by making a restrictor plate for the iac. Been selling them. :)

Dennis

[ausie]

It looks like it may afterall be piston slap. I was hoping it was all bull, dang, why do they do stupid things like that? I did some digging this morning after logging off and also at work. Unfortunately, there are some issues regarding piston slap with the 2001 Mach 1, 03 SVT cobra, and many other ford vehicles. if not all 4.6L engines build in the Winzor Canada plant, including the 5.3L and V10 motors had some piston mis-match problems. But yet many of the links that I dug into did not really point out the Mach 1 as a candidate, in fact quite the opposite. Engines built in the Romeo Mich. plant were said to be unaffected. Ford states that 1 out of 500 will have the piston slap issue, but the symptoms may well be caused by something else. Funny though, GM has more issues and law suits against them in the same issue, including the LS1 motor. Just about 90% of the reports were on GM vehicles.

http://www.f150online.com/forums/showthread.php?s=&threadid=8747

Now my concerns : could the 2001 SVT be affected as well, It may be probable since what I experience on cold starts occasionally (but not always). Usually about 2000 miles afer an oil change do I ever have any rattleing. If it is piston slap, should that not occur every time the motor is cold when starting? I did find some threads a while back but the timing chain tensioner was the target of discussion.

Oh well, I learn something new every day. My warrenty may indeed be expired according to Ford by way of mail, however, It has not been a total of 3 years or 36000 miles yet since I bought the car. It looks like I have more reading to do, I can only hope that my vehicle is unaffected, Time to get a 600HP crate motor.

[NO 5 OH]

It looks like it may afterall be piston slap. I was hoping it was all bull.

Sorry to rain on your parade... I'm just trying to lend some knowledge and not "speculate" about what the noise is. I have heard about the chain tensioners being at fault when the noise first appeared back in 2001 (such as in the older Mark VIII motors) but I never ran across any concrete evidence on that one. I've talked to the gentleman that tunes my car (and he builds mod motors as well... usually two or so a week) and he told me that piston slap is the culprit.

And it's not just limited to the newer motors either. I have a friend that lives in Illinois, and his 96 Cobra does it at start-up when it's sat overnight. It sounds just like mine does in my 03. My 01 didn't do it for as long on start up... but it had other problems besides that one. I'm actually glad I got rid of it (no offense, Ausie ;))

I hope that sorta answers your question about the different block materials having something to do with it Dennis. It really doesn't seem to have any rhyme or reason as to which ones do it. The motors do experience this... and I'm willing to bet it's more than what Ford says they do.

Shannon

[ausie]

I am not offended Shannon,
Piston slap it is. At least the issue is identified and that letting the engine warm up prior to putting it to load will reduce any excessive wear. I have been doing some digging into the issue.

One question to ask: if your motor has piston slap as is the case on cold starts, will that occur every time the motor is cold at start up? I only have it once in a great while. It is more apparent when I have synthetic 20w-50 oil in the motor and does not occur until about 2000 miles after the oil change. Ford attempted to identify other possibilities such as using an incorrect oil filter (one that is lacking a good reverse flow valve). Let me re-phrase that, I can only hear it once in a while.

I have heard this rattling noise while sitting at a stop light, but it goes away after I push the clutch in. I am baffled as to what the issue may be. However, I have also heard the same noise described in many of the piston slap threads on other sites.

It makes me wonder if I could find metal deposits in the oil filter. The next thing to do would be to drop the oil pan and inspect for fragments.

What other issues did you have with your 01? Just curious I guess probably more so since I have that year Cobra. I was considering on trading mine in for the 04 SVT but now I am not sure that would be a good thing to do.

[Firme]

some good info in this thread. :thumbsup:

one thing to note. I am convinced that the move to 5w20 was strictly due to EPA and Gas Mileage figures. I had a bunch of link (that I feel like digging up unless someone really wants me to) to .PDF files on EPA.GOV website send out to car manufacturers recommending that they switch to 5w20 due to the fact that the engine will warm up quicker, reducing NOX, and the "thinner" oil producing better gas mileage. The funny thing is back when a bunch of us were looking into this on Stangnet, including a petrolium engineer (guy really knew his oils), we found one of the original drafts of the document that stated "even though 5w20 causes quicker engine wear, that is offset by its benifits of less polution" :eek: , they since removed the document, guess it was too incriminating.

Although the heads on the DOHC 4.6 have been said to not bee able to move 20w50 well enough to oil the engine at a good rate (at startup and high RPM), 5w30 has done just fine. That is why I use AMSOIL Series 2000 0w30, the stuff is pure AWESOME in a bottle.

[34Ford]

Since the warmer temps mine is not as bad. Winter, its very noticable.
But you hear mine right when you let off the throttle to get another gear.
If your accelerating, or decelerating (sp) its quite. Its right at that moment when theres no load.

Or if in any gear, give it the gas and just lightly lift your foot, it rattles, let all the way off it quits.

Dennis

[NO 5 OH]

I am not offended Shannon

I probably did come off a little harsh... sorry if I did. You know this is the internet and what you say can always be interpreted totally different than what you intended ;)

Piston slap it is. At least the issue is identified and that letting the engine warm up prior to putting it to load will reduce any excessive wear. I have been doing some digging into the issue.

It is identified... but I hate there's nothing you can really do about it. Letting Ford replace the motor (if they'd go that far) won't fix the problem... you'll get the piston slap back eventually. The best thing to do is as you said let the motor warm up... you don't physically have to let it get to operating temp before you move it. As a rule I don't turn mine past three grand on the tach (sometimes not even 2500) until the needle on the temp guage is straight up in the middle.

One question to ask: if your motor has piston slap as is the case on cold starts, will that occur every time the motor is cold at start up? I only have it once in a great while. It is more apparent when I have synthetic 20w-50 oil in the motor and does not occur until about 2000 miles after the oil change. Ford attempted to identify other possibilities such as using an incorrect oil filter (one that is lacking a good reverse flow valve). Let me re-phrase that, I can only hear it once in a while.

Both my new one and old one "slap" after sitting overnight... or if driven to work and they sat for a period of eight hours or so. I ran 5w-30 Amsoil in the old Cobra for the longest time... switched to Motorcraft synthetic blend before taking it in for warranty work and it wasn't as noticeable. I actually traded the car the day it went in for it's last warranty repair. I recently switched the new Cobra to 5w-30 Amsoil after a sufficient amount of miles... it's made no difference in the slap at start up. I'm not so sure if I'd personally run a 20 weight oil in my car... that seems a bit thick in my opinion.

I have heard this rattling noise while sitting at a stop light, but it goes away after I push the clutch in. I am baffled as to what the issue may be. However, I have also heard the same noise described in many of the piston slap threads on other sites.

I actually heard this noise off and on if my old car was sitting idling with the clutch out. I never really checked this one out... but I'm pretty certain it's the throw out bearing making this noise. This makes sense as in your case and in mine the noise goes away when the clutch is engaged. It's either that or something in the tranny would be my guess. You can take that for what it's worth... I'm no expert by any means :p

It makes me wonder if I could find metal deposits in the oil filter. The next thing to do would be to drop the oil pan and inspect for fragments.

I don't know if I'd go to this extent... dropping the pan with the motor in the car requires totally dropping the ENTIRE front suspension from out underneath it. I'd only do this if you were doing headers ;) I actually have a Canton 7 qt pan on my car now due to the long tube installation... rolling the motor over by jacking up the oil pan didn't work for me :( Ask anybody that's done headers and they'll probably tell you the easiest way is to get the k-member out of the way.

What other issues did you have with your 01? Just curious I guess probably more so since I have that year Cobra. I was considering on trading mine in for the 04 SVT but now I am not sure that would be a good thing to do.

Oh lord... this is turning into a novel :)

Piston slap on start up
Oil smoke out the tailpipes on start up, if sat over night (probable valve seal failure or oil getting into combustion chamber)
Vibration in driveline in 3rd gear (they never heard this noise :rolleyes: )
Transmission grinded into 2nd and 3rd when cold, until car up to operating temp (tranny was on it's way out when it got traded... would pop out of 2nd gear sometimes when accelerating)

I think there might have been a few more things... but I've forgotten them since it's been long gone now. The new Cobra helped me forget about the bad things wrong with it :D Trading mine in on the 03 was the best thing I could have done... I got a Cobra with a blower from Ford with a warranty :) This one has been much better than the last one... I'm very happy with it. Trading in your case may not be the best thing... I'm sure you really like your car and I bet it looks cool as hell with the BBS wheels on it :thumbsup:

Shannon

[ausie]

Shannon,
Ouch, it sounds like you had a few problems with it. If I ever decide to trade in my 01 for an 04 SVT, I still have all the stock parts to put back on. The good thing is that my cat-back and wheels will fit an 03-04. Eventhough I put down $10,000 cash and got a $1500.00 rebate along with ford 0% financing, I would brake even if I traded it in. I have seen rebates offered by the dealer on the 04 model I would still loose money on the trade. My car is in very good shape with 25k miles. I had to do a few adjustments to it so it runs better (new EGR valve, IAC, and altered the throttle stop since the tps was off when the throttle plate was closed). The only complaint I have is that it still has that 4x4 stance it came with. It would be hard to part with (unless I test drive a new SVT).

This past thursday I changed the oil from 20w-50 to 0w-30 to see if there is any difference. In physical appearence, the series 2000 AMSOIL 20w-50 is very much the same as the 0w-30. The 20w-50 poured like water as did the 0w-30. The only difference is that the 20w-50 will cling longer. I would not use conventional 20w-50 oil since it is thick as moleassiss.

I have been doing some more digging, I cannot find many links directly associated with a 2001 Cobra (probably due to the smaller production numbers). I have heard some sound clips on the pistonslap.com web site from a GM vehichle, It sounded worse than a Cummings (sic) deisel. Ever hear piston slap in a deisel? lol....

One thing for sure, abnormal oil consumption is associated with piston slap as well as the rattling sound. That would at least explain the carbon buildup in the motor which is one of the main issues with the 01 Cobra.

However, the plugs did not show the characteristics of burning oil. Flat black plugs may indicate running too rich, but oil burning is also a cause of carbon build up. I tracked my problem down to a faulty EGR valve which was not functioning. After replacing the EGR valve, and installing a free flowing cat back, my plugs exhibit normal characteristics. Prior to that, they would get fouled up within 500 miles.

I think I am getting way off topic here. Sorry about that. I have not yet learned to get the point across in a few sentences.

I have seached the topic until I got sick and tired of openning up the same pages. I did however find some marketing hints that the MACH 1 motor was supposed to be improved as not to experience piston slap. I guess they were wrong.