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What is this noise?

  • normal

    Votes: 1 20.0%
  • leaking anti-drainback valve

    Votes: 0 0.0%
  • timing chain slap

    Votes: 2 40.0%
  • bad cam actuator

    Votes: 2 40.0%
  • HPFP

    Votes: 0 0.0%
  • other

    Votes: 2 40.0%

  • Total voters
    5
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'09 CTS DI FE1 Luxury
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Discussion Starter #1
My car has been sitting for longer periods lately and seems noisier on cold starts for about 2 seconds until oil pressure builds. Does this sound normal? There are no codes set or pending and the engine runs great. TIA

 

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2009 CTS 3.6L DI rebuilt to FE3 J55 G80 3.42:1
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Could be one of the cam actuators failing to lock at shutdown and rattling around until the oil pressure builds enough to control it. Just a guess based on a bad cell phone recording, worth what you paid for the diagnosis.
 

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Discussion Starter #5
Thanks for the replies. I don't remember hearing this noise before and suspect that it might well be a cam actuator. The only thing I'm sure of is that it's in the top end and quiets down with oil pressure. Might it be worthwhile to replace the actuators before doing the timing chain? I haven't had any codes for the chain and the engine has had 5k oil changes for it's 75k life.
 
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When you're in there, change both chains and actuators. Too much labor with not that much $$ in parts.
 

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2009 CTS 3.6L DI rebuilt to FE3 J55 G80 3.42:1
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I wonder if an actuator flailing at startup could be seen on a Tech 2?
 

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Discussion Starter #8
I'm not sure but I thought that the actuators could be replaced with far less labor than doing the chains. That's a good idea to check the actuators with my tech2. I'll post back.
 

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I'm not sure but I thought that the actuators could be replaced with far less labor than doing the chains. That's a good idea to check the actuators with my tech2. I'll post back.
Just a note of caution: When I took my car to the dealer for chain/guide/actuator replacement following a single P0008 code event, they ran scan tool diagnostics before performing the repair. Everything was "within limits". Yet the car hesitated at throttle tip-in, and the chains rattled. The engine performs much better after the repair.

We know GM programmed in loose chain wear limits in a self-serving move to reduce warranty costs, and electronic diagnostics don't always tell the whole story. And this would be a transient, although it sounds like in your case, repeatable event.
 

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Discussion Starter #11

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Go ahead, blame me. Everybody does 🙄
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Discussion Starter #14
Oh well, I'll see how the cam positions look at cold start and go from there. Not overly concerned yet since it's low miles, runs great and there are no codes.
 

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2009 CTS 3.6L DI rebuilt to FE3 J55 G80 3.42:1
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Oh well, I'll see how the cam positions look at cold start and go from there. Not overly concerned yet since it's low miles, runs great and there are no codes.
I know at this point it is just a guess, but if you do indeed have actuator problems that are slapping your chains around at startup I would not consider this to be a minor problem. That is a lot of noise and banging on precision components. It should be obvious that chain slap at startup is hard on the chains. It's an expensive job, but could also make your car run well and last a long time. And yes, if these components are not in good condition your engine will most definitely run better and the fuel economy will improve.

You should not be overly confident in the lack of codes, that noise is trying to tell you something.
 

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Discussion Starter #16
Luckily for me the PCM will throw a P0008 code long before anything bad happens. On my last highway trip I averaged between 26 to 28.5 mpg and on the slow stuff it still gets 18+ on short trips. If the timing chains are in need of replacement, it really doesn't feel like it and none of the usual causal factors for premature chain failure are present. The oil was changed every 5k miles, only 5w30 M1 was used, the same dealer performed all changes and the engine loses under a qt in 5k miles. Admittedly these factors guarantee nothing but they do make a good argument against premature chain failure without any codes presenting.

Remember that this noise only happens after sitting for days. I just cranked it over with the throttle floored to build oil pressure before starting and the rattle noise was virtually non existent. Joseph Upson had the same rattle and claims that 10w40 solved it for him. His theory was that poorly controlled actuators during low oil pressure startup (they unlock at 15 psi). It seems plausible to me. I've heard a recording of a bad actuator (unlocked) and it sounds far worse than what I recorded. You can hear a loud slapping sound as the actuator slaps against the stops before oil pressure brings it under control. Then again, maybe I'll get a P0008 tomorrow proving that I need new chains. Time will tell.
 

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I see denial is not just a river in Egypt.
 

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Discussion Starter #18
You're funny. How about while I'm replacing my still serviceable timing chains I also replace all the sensors and coil packs, fully rebuild the suspension, upgrade to FE3 parts, J55 brakes and 19" wheels and tires. I'm sure that it would drive better. What else do you recommend for my $5000 used car? :unsure:
 

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You're funny.
No, you're the funny one! You post what sounds like a mechanical, internal engine problem and promptly proceed to dismiss any suggestions that involve spending money on car maintenance. I get it, nobody likes to spend money repairing their cars. But you bought an 11 year old car just like I did. Did you think it wouldn't require maintenance?

still serviceable timing chains
If the components in question were "still serviceable" they wouldn't be making noise.

How about this: Don't fix it, drive it till it fails. That's free, better?
 
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