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  1. #1
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    Camshaft Chain Tensioner Failures - Head's up Everyone

    If you have changed, or are about to change camshafts, it is extremely advisable to replace at the very least the camshaft chain tensioner assembly with a unit meant for the 6.1 engiens (4 leaf springs instead of 2). There are a significant number of failures that have occured and continue to occur, due in part to the spring-steel tensioners that apply pressure to the phenolic or delrin sliders, that apply pressure to the camshaft chain itself. Although there have been a couple of failures where the front of the engine has never been opened, the common theme might be that high-rpm excursions on an all-too regular basis is putting stress on the tensioner assembly such that it fatigue-fractures and fails.

    I you feel the engine is running rough(er) than normal, shut down and investigate immediately. If the tensioner assembly has failed it might allow the cam to move in and out of phase, or jump a tooth, especially at idle. This is how it might manifest itself (make itself known).

    I shouldn't have to state this either, if your oil pressure drops to zero and you get a chime and the oilcan warning light illumintes (like I did when the relief valve stuck open due to metallic debris), shut down immediately and coast to the side of the road (IF you have that skillset to do so while moving). Mains and rod ends can handle no-load zero oil pressure for an unusually long time...the key being "no load". It could be a faulty sending unit...if it's not then likely something much more serious. Read on;


    Working on a 5.7 which demonstrated low oil pressure (idle - 6psi), then zero pressure at the next stoplight (again @ idle with resulting audible low oil pressure chime and oil can LED on cluster - vehicle was immediately shut down and flatbedded).

    A brief start-up next day (cold) demonstrated noisy valvetrain and a slight surging every second or so. Oil filter was removed, with oil filter still off and accelerator floored vehicle was turned over; zero oil exited the oil filter mount.

    Straining the (drained) oil past a (very) strong magnet resulted in zero metallic debris. Sweeping the oil pan exterior resulted in audible metal fragments in bottom of pan. Magnet was used to move the fragments to oil drain plug area and evacuated (see pic).

    Appears to be tensioner spring structure debris, I suspect the (minor) surging observed this AM during cold start-up is due to poor cam phasing as a result of tensioner malfunction;



    Interested in learning/sharing about other tensioner failures, specifically:

    - why they fail
    - how the failures manifested themselves (how was the problem discovered)
    - how much damage was incurred
    - warrantee coverage scenarios (not likely here given a cam install)
    - solution(s) to prevent repeat-failures

    Couple of questions:

    1) Has the design changed since 05'?
    2) Is there an aftermarket version that might be superior to the OEM version?

    Obviously the front end will come off shortly to get the complete picture, namely the tensioner failure and (what appears as) oil pump failure. I will open up the oil filter to see just how much debris is present.

    Looking for feedback from those-in-the-know, thanks...

    EDIT: to save folks reading the entire thread, here are the pertinent PN's:

    6.1 Timing Kit (which includes a 4-leaf tensioner plate): 5037579AB
    6.1 HP oil pump: 5037687AB (no increase in volume though)
    Last edited by Hemissary; 04-25-2011 at 02:14 PM.
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  2. #2
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    Its not the first one. Bet if you do a search you'll turn up a few. Crower makes an aftermarket double roller and tensioner if I'm not mistaken.
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  3. #3
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    They fail, Erik got a fun surprise when he did electrofried's cam when the tensioner pad was gone, the slop in the system caused the computer to learn some retarded cam timing. Had to doa reset/relearn with a starscan to make it right.

    I have heard of a few more that have failed and one or two big cam motors that cracked the plate.

    -Robert

  4. #4
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    Was there anything left of the plastic guides?I have seen this before many times. The chain as it ages binds up and acts as a saw on the plastic guides.Once they break apart the chain will saw through the metal guide supports on the thrust plate.This in itself will not cause the oil pump to fail but if enough metal shavings got past the screen it is possible.It is also possible that the plastic shavings from the guides clogged the pickup screen. Unfortunately these are all just guesses based on past findings till you get the oil pump out.
    BTW you can swing the oil pump off a 5.7 and get the pickup tube out without dropping the pan.....if this is a 6.1 you will need to drop the pan to remove the support on the pickup tube from the main cap.
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  5. #5
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    See Dudeiwin86 post #37: http://www.lxforums.com/board/showth...=198289&page=3

    He had exactly what you're talking about
    2008 Magnum BB R/T Hemi Registry # 1584 PPP Stage 2 Cam, JBA Shorty Headers, JBA High Flow cats, Heartthrob Exhaust, Eagle Intake, LMI Intake, MTCM, Blue Tops, ProTorque Converter, SRT Rear, Techo Strut Brace, lowered, Tuned by Diablotoona SOLD--2005 Mineral Gray AWD Hemi Registry # 1154

    Quote Originally Posted by Hemissary View Post
    For the work being performed, length is far more important than diameter :^)

  6. #6
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    Thanks gang; I'll add more info/pics when I get what's left of the tensioner and the oil pump off. Good tip about the 5.7 pump Eric, pan will likely have to come off anyways to properly clear it of debris.

    I take it the OEM tensioner design has not been updated?

    How many folks have R&R'd this failure and gone on to log significant miles without further complications?

    Or, how many have experienced secondary failures likely as a result of this problem?

    If one had a choice which of these items would you choose, versus the OEM tensioner:

    http://www.lxforums.com/board/showthread.php?t=170207

    or

    http://www.lxforums.com/board/showthread.php?t=190338

    Are there any other offerings?

    Thanks again...

  7. #7
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    Unless you need to adjust the cam use the stock setup......both the aftermarket pieces use the stock tensioner/thrust plate anyway.

  8. #8
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    Quote Originally Posted by GasGunR View Post
    Its not the first one. Bet if you do a search you'll turn up a few. Crower makes an aftermarket double roller and tensioner if I'm not mistaken.
    crower is a single chain, manley has a dual chain...

    cam if wanted or needed i can see and get pics of the 08 stocker and manly tensioner plate i have.

    Quote Originally Posted by Hemissary View Post
    Thanks gang; I'll add more info/pics when I get what's left of the tensioner and the oil pump off. Good tip about the 5.7 pump Eric, pan will likely have to come off anyways to properly clear it of debris.

    I take it the OEM tensioner design has not been updated?

    How many folks have R&R'd this failure and gone on to log significant miles without further complications?

    Or, how many have experienced secondary failures likely as a result of this problem?

    If one had a choice which of these items would you choose, versus the OEM tensioner:

    http://www.lxforums.com/board/showthread.php?t=170207

    or

    http://www.lxforums.com/board/showthread.php?t=190338

    Are there any other offerings?

    Thanks again...

    as posted i got the manley..it has room for more advance or retard than the crower....and its a tad more expensixe...but the main reason i went it was because crower was on back order (i think it still is) and the person i ordered from never told me...so i ordered the manly from arrington because they had it in stock. i can get more detailed pics if wanted.
    Last edited by viperkota; 03-16-2010 at 12:38 PM.

  9. #9
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    I had a plastic guide break about 1/3 from the bottom. Never knew it until I had other problems and had to drop the pan. The plastic piece that broke was sitting in the bottom of the pan. I replace the tensioner with plate. When going back together i went back with same stock timing spockets and chain...about 3k miles, no problems (that i know of). I did change the cam at the same time to more suit the build.

  10. #10
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    most of what i was going to mentioned has already been covered...

    the aftermarket cam chains use the STOCK plate and tensioner...
    so dont waste your money unless you want to advance/retard it as Erik mentioned.

    i had a similar failure, as was also posted.
    for good measure, i will repost my pictures for the people who didnt follow the link:











    ---

    RobAGD, when you say
    caused the computer to learn some retarded cam timing.
    do you mean that literally?
    as in the timing it learned was retarded (not advanced)

    ive had an odd issue with my off idle performance that ive never fully been able to solve.
    a lot i attribute to the torque converter that i dont want to change. but this might be an easy route for me to test (that doesnt involve tearing things down) and see if it wakes something up.

    --

    i wouldnt be suprised if i have pieces of that spring in my pan.... all were large pieces so i never concerned my self with them.... it was either put the motor back together so i could goto work the next day.. or suck up more of a tear down.... i went to work. and 30,000 miles later, i still have good oil pressure and no real problems.

    the idea of using a big magnet is interesting tho... i will see what i can move to the front of the pan, and then use an extendable magnet to go down in there and see if i can pull anything out.
    (the cover will be back off sooner or later to put her back to stock)

    as far as probable cause?
    -over tightening the cam plate bolts
    -lots of high rpm's, specifically from down shifting to gear brake, etc

    as you can see my plate was cracked right at the bolt.
    i had already installed one cam, and a new one was going in and we found the mess pictured above.

    you can also see the wear marks on the plate where the chain was rubbing on it.
    once the plastic piece broke, it was curtains .

    the thing about it was, we have no idea how long i had been running like this (anywhere from 1-25,000 miles). and i never noticed a change in performance.

    the first couple pictures were taken just after removing the timing cover.. you can see how the metal springs lay, just as they were. untouched.

    feel free to ask any questions about my experience....
    ive just kinda rambled off some thoughts as they come so far.

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  11. #11
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    Quote Originally Posted by dudeiwin86 View Post

    RobAGD, when you say
    do you mean that literally?
    as in the timing it learned was retarded (not advanced)

    ive had an odd issue with my off idle performance that ive never fully been able to solve.
    As in the car was driven so long with the chain slapping around not only was it using the oil pump as a guide (and cutting through) but the PCM actually learned the advance/retard dance the chain was doing as normal....I know,I know.....I swear it's true.I took the motor apart to do a cam and found the carnage.Cleaned it all out,replace the timing set,button everything back up and when I started the car it popped an 0016.I though I had the cam off a tooth.....so took it all back apart....realigned the marks...buttton it back up and 0016 code.....now I was pissed.Took it apart again and rolled the motor over till the marks lined up and they were perfect.
    Took 30 seconds for a dealer to do a cam/crank relearn and the car was perfect.And it had to be done with a scan tool......no fuse or battery pulling,capacitive discharge nothing,not any other trick in the book was going to get it to run right.


    If anyone wants to read an old thread this is the very first time the tensioner issue was run into......
    http://www.lxforums.com/board/showthread.php?t=85311
    Last edited by Hemi31; 03-16-2010 at 01:34 PM.

  12. #12
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    i dont doubt you on that Erik,
    im just wondering how long mine was out of whack... and if it learned some nonsense.

    never had a code for the cam timing, however. before, nor after, the cam swap.
    i dont think my chain was that far out tho....

    look at some of the LS1/LS2 stuff.. they dont even run a tensioner on the stock setup... my chain was about as slacked as their stock one without a tensioner (not good.. but not bad). so i dont think it was out long enough to really get bad. funny because the LS3 now has a tensioner

    might be interested to do a relearn tho, just for grins.

  13. #13
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    AS I have seen this several times, 3 times on my own 392.

    My issue was me, LOL

    When installing the new alinemet dowles (new stroker crank) for the cam gear and ATI pulley, I had created some burring of the dowl, and the lower cam gear did not slide very freely, (it moved but not much withing the slack of the plate and oil pump)

    So the first time, the lower cam gear was pushed to far back and it cut throw the tenshion plastic, metal, and cut the whole dam cam plate in to 2 peaces...

    So replaced with new parts, (and diffrent cam ) I thought I would just push the cam gear foward a little to aline it better this time. Well 6k later, I went to put in another cam, and what did I see, the plastic was gone and the metal was on its way out.

    Replaced with new parts agin, ( with a diffrent cam agin) but replaced the dowel and made 100% sure there was not binding on the lower gears movement) When I pulled the motor 5k later there was no issue to be seen...

    Im not sure if this helps, and Im sure most would not even put there busness out there like this, but hey if it helps
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  14. #14
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    It's appreciated by everyone I would hope; the end-result in this particular case...there is zero oil pressure. I have yet to find time to pull the front off to get to the oil pump, but I'm not looking forward to it.

    Today I'm going to make time to cut open the oil filter and examine the filter element to hopefully get an idea as to whether the oil pump has destroyed itself...which would not bode well for the rest of the engine (metallic particle-wise).

    As mentioned, the hope would be that somehow the pickup tube has been plugged in a manner that would 100% prevent oil flow, but I'm not holding my breath.

    Again, the main reason I created the thread is because I remembered(!) reading about dudewin86's problem...probably shortly after this particular cam/head install. Made me "very" nervous because no one had mentioned prior it being a wise idea to replace the tensioner assembly at the very least.

    My hope is that the title motivates folks to replace the tensioner "no matter what" whenever they have the front open...cheap insurance to say the least.

    What bothers me as that with a roller there is relatively little negative/positive loading no matter how aggressive the engine is spooled or unspooled. I did not like the tensioner design the first time I saw it, I like it a lot less now.

    There are at least two failures modes from what I see based on people's submissions; backplate fatigue (over-tightening is not the issue - read on) and tensioner assembly failure.

    Regarding the fatigue-failure of the back plate; what I believe is happening is that the camshaft gear is mounted such that it is slightly off center, or it is slightly out of round (center pilot not machined-drilled correctly). What appears to be happening (a portion of my contract work is discovering root-cause) is that as the assembly rotates causing continuous tension and slackening which causes the backplate to flex. Where? Right at the point it would be attached to the fixed structure (the block).

    That crack I see is definitely fatigue-type failure due to a bending load dudeiwin86. The only way that can happen is from repeated flexure until the work (the metal) reaches it's glass-transition point.

    The other failure appears to be the spring-steel structure that applies tension (through the phenolic skid guide) to the timing chain. I don't have enough evidence to point in any particular direction until a get a new unit to look at. Now which part of the assembly gives way first is anyone's guess.

    So the other thing I do after (hopefully) determining root cause, is prevention; in this vein it would be "very" advisable to check the runout or orbital eccentricity of the camshaft gear after securing the assembly in place. It is highly unlikely the smaller drive (crankshaft) gear is eccentric.

    So the simplest way to do this would be with a dial gauge and mag-mount on the block face, with the indicator bead on the side of the timing chain face and check every 90 degrees for displacement. I think this will be critical to avoiding future failure.

    IMO this is why these types of threads are "so" valuable to all of us...the idea of preventing damage to a another brothu's HEMI.

    It's going to be interesting to find out why there is zero oil pressure; I believe it was Eric who has suggested tensioner remnants might have blocked the pickup, but it would have to have been 100% complete given zero oil comes out the oil filter boss when cranked over. I wanna believe it, but my gut is telling me the pump drive gear has been compromized...with the resulting carnage.
    Last edited by Hemissary; 03-16-2010 at 03:39 PM.

  15. #15
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    10-4 on all of that Hemissary.. keep us posted with what you find out about the oil pump issue. i would hope its only clogged, but i would think it oculd still build pressure even with some big(but flat) metal in the way.... 0psi is not a good sign.

    and ill double up on the "replace the plate/tensioner assembly every time you have the motor open". i suggest that to every person doing a cam swap.

    1362#sublime was also there doing most of my teardown with me when we uncovered my pictures above. he knows all too well :(
    Last edited by dudeiwin86; 03-16-2010 at 03:35 PM.

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