Page 1 of 2 1 2 LastLast
Results 1 to 10 of 12

Thread: keyway failure on a 20v?

Hybrid View

Previous Post Previous Post   Next Post Next Post
  1. #1
    Moderator Sam-Q's Avatar
    Join Date
    Dec 2008
    Name
    Sam
    State
    VIC
    Location
    Endeavour Hills
    Country
    Australia
    Posts
    4,242

    Default keyway failure on a 20v?

    I have had my engine stuff up at max revs, and as it looks the front crank pulley is turning when I crank it and the cam belt doesnt turn. So from this I think I have somehow managed to break the key out of the keyway for the timing belt drive gear. I have heard of people wrecking the keyway for the main pulley but not this sucker.

    Has anyone ever heard of this?

    I am hoping my crank and some of my valves arnt damaged or else I will be pissed off.
    My website: SQ Engineering - 4AGE and 3SGE upgrade/replacement parts

    - SQ Engineering on facebook -

    Please e-mail to contact me instead of sending a private message on here.

  2. #2
    Senior Member KE70's Avatar
    Join Date
    Dec 2008
    Name
    Alek
    State
    VIC
    Location
    Lalor
    Country
    Australia
    Posts
    150

    Default

    Dammmm, that would have been scary.

    Are the keyways the same across all 4ages?

  3. #3
    Senior Member Matt-AE86's Avatar
    Join Date
    Dec 2008
    Name
    Matt
    State
    WA
    Location
    Perth
    Country
    Australia
    Posts
    971

    Default

    Sam, if you remember ages ago Josh/mr2drift killed the keyway on his 16v 4age when it was turbo. He thought it was due to milling off the front half of the crank pulley.

    I'm pretty sure he got a new one and replaced it.

  4. #4
    Veteran slydar's Avatar
    Join Date
    Nov 2008
    Name
    Dimitri
    State
    QLD
    Location
    Brisbane
    Country
    Australia
    Posts
    3,096

    Default

    its a some what common problem. unless youve put cams in your engine or had machine work done your valves will be fine, no 4age is an interference engine standard.

  5. #5
    Senior Member Hen may possibly be a nut's Avatar
    Join Date
    Jan 2009
    Name
    Hen
    State
    Victoria
    Location
    Mt Macedon
    Country
    Australia
    Posts
    909

    Default

    As you probably know, the timing pullye and crank pulley run on the same key, so it seems a little strange that one would go and not the other.

    I once snapped a crank just behind the timing pulley. Apparently it's not an unknown problem, but then your crank pulley shouldn't be turning.

    Not hard to get the plastic covers off and see what's going on though.

    Hen

  6. #6
    Veteran slydar's Avatar
    Join Date
    Nov 2008
    Name
    Dimitri
    State
    QLD
    Location
    Brisbane
    Country
    Australia
    Posts
    3,096

    Default

    yeah, the timing gear has the resistance of the valve train to fight. rest doesnt have much resistance at all.

    its a pretty common problem. the 2 gears on the one key way is the problem in theory. the 2 pulleys move/vibrate ever so slightly all the time, at different frequency's, due to their different loads. putting a lot of fatigue cycles on the key.

    Atlantic engine have 2 separate key ways, 1 for the timing gear, and another for the accessories.

    sheering the key way is kind of a mark of honor. you must rev your engine pretty hard sam fairly often.

  7. #7
    Senior Member Vezza's Avatar
    Join Date
    Dec 2008
    Name
    Vesley
    State
    VIC
    Location
    Geelong
    Country
    Australia
    Posts
    270

    Default

    Haha, the new in thing... you ain't cool unless you've sheared a keyway. We can start a KS club, keyway shearers.

    Just wondering Sam, has the crank pulley ever been removed and reinstalled? Maybe if the bolt wasn't torqued on tight enough, it could've had a slight play, rocking back and forth until it sheared the keyway?

  8. #8
    Senior Member
    Join Date
    Dec 2008
    Name
    Dusty
    State
    VIC
    Location
    Lynbrook
    Country
    Australia
    Posts
    581

    Default

    definately that?? it could be possible your tensioner has died and possibly sheared off teeth on the timing belt? I have seen it happen before, otherwise a seized cam and then snapped, odd if neither cam is moving... just soem food for thought

  9. #9
    Moderator Sam-Q's Avatar
    Join Date
    Dec 2008
    Name
    Sam
    State
    VIC
    Location
    Endeavour Hills
    Country
    Australia
    Posts
    4,242

    Default

    KE70: I can only assume so, unless thats what caused the problem as by memory I fitted a 16V keyway??

    Matt-AE86: I find it a bit odd that machining the front of the pulley off might of killed it?? I would of thought that it would of reduced the load because there would be less innertia on it?

    slydar: I thought it was only a common problem for the actual front pulley not the cam timing gear. As for the whole intereference thing I thought about it and I have two things that make it an unknown; I was doing more revs than what the engine is normally limited to and also I am running a 0.8mm trd head gasket. Just for the record I was doing 8500 RPM in third at the time.

    hen: the covers will come off soon, I just made this thread yesterday after being towed home. I just parked the car and left the damn thing for the day.

    Vezza: I did have it off and I will check for freeplay later, although I would of thought the main pulley would go first?? also this isnt the first time I have broken something in a new way. A while back I smashed the diff so good that one of the teeth broke in such a way that shot out through the rear of the diff housing, and that steel isnt thin...


    dustyae86: I tottaly didnt think of the fact that I am missing a few teeth off my timing belt. I will have a look thanks
    My website: SQ Engineering - 4AGE and 3SGE upgrade/replacement parts

    - SQ Engineering on facebook -

    Please e-mail to contact me instead of sending a private message on here.

  10. #10
    Moderator Sam-Q's Avatar
    Join Date
    Dec 2008
    Name
    Sam
    State
    VIC
    Location
    Endeavour Hills
    Country
    Australia
    Posts
    4,242

    Default

    well I have found the problem, it looks like I did use all the right parts however the pulley was missing the top part of the keyway that holds the semi-circle shaped key in place. So while it would of worked for a while the key eventually curled out for the lack of a better explination. Looking closely at it, it amazes me how little of the key is used to transmit the torque to the main pulley, no wonder they fail. I will fit another pulley tomorrow and find out if my valves are bent.
    My website: SQ Engineering - 4AGE and 3SGE upgrade/replacement parts

    - SQ Engineering on facebook -

    Please e-mail to contact me instead of sending a private message on here.

Page 1 of 2 1 2 LastLast

Similar Threads

  1. Fuel pump failure
    By 70rolla in forum Technical - Questions
    Replies: 3
    Last Post: 17th November 2011, 05:03 PM
  2. help where to get lamp failure unit.
    By Gotcarbs in forum Brisbane & QLD Events and Discussion
    Replies: 7
    Last Post: 20th April 2010, 09:53 AM
  3. backlash, prolonging failure
    By seek in forum Technical - Questions
    Replies: 14
    Last Post: 28th November 2007, 09:15 PM
  4. brake failure
    By DriftPlease in forum Technical - Questions
    Replies: 12
    Last Post: 10th April 2007, 06:23 AM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •