Timing Failure, Top End Rebuild.. Fully Documented.
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Cadillac CTS First Generation Forum - 2003 - 2007 Discussion, Timing Failure, Top End Rebuild.. Fully Documented. in Cadillac CTS Coupe, Sport Sedan and Sport Wagon Forums; Hey I'm compiling all my posts into one ongoing. Summary: The car is a '05 CTS 90,000 which has the ...
  1. #1
    briggy's Avatar
    briggy is offline Cadillac Owners Enthusiast
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    Post Timing Failure, Top End Rebuild.. Fully Documented.

    Hey I'm compiling all my posts into one ongoing.

    Summary:

    The car is a '05 CTS 90,000 which has the LY7 V6 Engine *same used in many GM brands) This particular engine has a higher than normal timing failure rate. In my case worn tensioner brackets and a worn chain led to a primary chain slip. Which resulted in impacted valves. Prior to the failure I was noticing a ticking noise on cold starts, a quick tap on the throttle smoothed it out. In hindsight this was the timing chain clicking, higher rpms pushed out the tensioner. This resulted in less slack on the chain. This particular engine was burning about 2 quarts of oil every 3,000 miles.






    http://www.youtube.com/watch?v=szA7xa3II9w
    This is what it sounded like. Very distinct sound of low compression


    I did a pressure test which resulted in the following values.

    left bank right bank
    40psi 50psi
    40psi 85psi
    50psi 100psi

    These all pretty much confirmed something was wrong with either the valves or pistons. Based on research done the safe bet was impacted valves from the timing slip.

    Timing Chain:



    Exposed timing chain





    Autozone *cloyes) replacement kit




    I purchased a timing kit set from Autozone, the kit though rebranded duralast is actually a Cloyes set which looks to be OEM. Total price out the door on the kit is around $200.


    Head Removed:











    Couple things to note, on visual inspection the valves look fine. No point of impact on either the piston or valve. I tested it by pouring some fuel in the inlets. The intake side sealed ok, however the exhaust side began dripping pretty quickly. Survey side exhaust valves on both banks damaged. I'll be dropping these suckers off at the machine shop today.

    Will update as I go along.
    CTSM likes this.

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  3. #2
    Longsnapper52 is offline Cadillac Owners Connoisseur
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    Re: Timing Failure, Top End Rebuild.. Fully Documented.

    What a nightmare....thanks for documenting this for all of us.

  4. #3
    Spyke's Avatar
    Spyke is offline Cadillac Owners Connoisseur
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    Re: Timing Failure, Top End Rebuild.. Fully Documented.

    Briggy, thanks for thw write up my friend!

    I feel your pain, man! Hope you like what you are doing!

  5. #4
    ghettomike's Avatar
    ghettomike is offline Cadillac Owners Master
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    Re: Timing Failure, Top End Rebuild.. Fully Documented.

    is it just me or does that engine seem overly dirty? looks to be piled with gunk... what oil and fuel do you use?
    the pistons look like they have been through hell.

  6. #5
    Longsnapper52 is offline Cadillac Owners Connoisseur
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    Re: Timing Failure, Top End Rebuild.. Fully Documented.

    ^^^^^TRUE.....should pistons be that dirty?

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    ghettomike is offline Cadillac Owners Master
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    Re: Timing Failure, Top End Rebuild.. Fully Documented.

    im no expert as i have never had a engine apart... but that looks like it was opened up and left sitting like that for a long time.

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    Longsnapper52 is offline Cadillac Owners Connoisseur
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    Re: Timing Failure, Top End Rebuild.. Fully Documented.

    Maybe we've seen too many fuel additive commercials that show pristine engine parts. You've got to figure after a couple of million small explosions, the pistons and valves would get kind of dirty

  9. #8
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    Re: Timing Failure, Top End Rebuild.. Fully Documented.

    That's called a shit ton of carbon build up...... If the thing is burning a couple of quarts of oil every 3000 miles, it is no wonder the pistons and valves look like that. Every car that is burning oil at that rate more than likely has engine internals that look like that. Briggy, good work by you for tearing it apart and fixing what GM has to know is a serious problem.

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    tp2010 is offline Cadillac Owners Fanatic
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    Re: Timing Failure, Top End Rebuild.. Fully Documented.

    I'm at 80k miles and I have an 05 3.6l... This has kinda been worrying me. lol

  11. #10
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    Re: Timing Failure, Top End Rebuild.. Fully Documented.

    Quote Originally Posted by ghettomike View Post
    is it just me or does that engine seem overly dirty? looks to be piled with gunk... what oil and fuel do you use?
    the pistons look like they have been through hell.
    90,000 miles 87 octane, with the occasional fuel cleaner. From what I understand this is the norm on these engines.

  12. #11
    briggy's Avatar
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    Re: Timing Failure, Top End Rebuild.. Fully Documented.

    Quote Originally Posted by ghettomike View Post
    im no expert as i have never had a engine apart... but that looks like it was opened up and left sitting like that for a long time.
    Done a few tear downs myself, this one is excessive. What surprised me was how lose the carbon was, no doubt from fuel breaking it down. I talked to a caddy tech he says that's the norm. Suggested I use gm build up cleaner and trans fluid let it soak in the cylinders for a few days to free up the rings.

  13. #12
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    Re: Timing Failure, Top End Rebuild.. Fully Documented.

    Quote Originally Posted by tp2010 View Post
    I'm at 80k miles and I have an 05 3.6l... This has kinda been worrying me. lol
    don't like to tell people to spend money, but replaced timing chain is cheaper then replaced heads. I always told my wife to blip the throttle on start up to increase the oil pressure and thus smooth out the engine. The day it broke my mother in law was driving it *literally started then died).

    One clear sign of pending failure is clattering on cold starts from the timing belt. If you notice you blip the throttle and it goes away immediately your timing chain is on the way out.

  14. #13
    bigblock66 is offline Cadillac Owners Member
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    Re: Timing Failure, Top End Rebuild.. Fully Documented.

    That it I've seen enough on the timing issue with this engine I'm going to change that to. I'm betting the lower end sound i"m hearing which I was thinking was the start of main bearing going bad but with only 71K on it with isn't that many miles to hearing mains already. Has any one had an issue with the chains after first change out. was looking at it the time it takes me to get to it I would have had the whole engine and tranny, engine on stand,heads off on my Chevelle lmao.

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    Re: Timing Failure, Top End Rebuild.. Fully Documented.

    Quote Originally Posted by bigblock66 View Post
    That it I've.......already. Has any one had an issue with the chains after first change out. was looking at it the time it takes me to get to it I would have had the whole engine and tranny, engine on stand,heads off on my Chevelle lmao.
    Bottom end is sound. I've never heard any complaints of main bearing failure. What type of sounds are you referring to exactly ?

    If I had a stand, and a cherry picker I probably would have taken out the engine out.

  16. #15
    bigblock66 is offline Cadillac Owners Member
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    Re: Timing Failure, Top End Rebuild.. Fully Documented.

    well the some of the other post talked of a knock in there engine before chain failure. The knock I hear is a couple knocks on the first start up of the day that i notice but I'm not the one driving it must of the time. If it is main I'll now for sure this winter when the metal is colder and has a few tenths more of clearance.

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