04-01-2019, 02:58 PM | #1 |
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Engine rebuilt, new weird sound
I have just got my engine rebuilt with cp pistons and rods. There was no problem with the engine tbh I just got an itch to do it since my car is at 60k miles. Meanwhile at it, I added the vtt crank hub fix to it as well. However, now that I got the engine rebuilt I have a new knocking sound at 800-1400 on throttle. It sounds like an injector knock but in a deeper way and it feels like it comes from the top of the engine. I know it's almost impossible to understand it from video or description but I have three suspects.
-Do you change the valve lifters(rocker/tappet) when you built an engine? Do you think since I reused my old ones, they may be the problem? -An other mechanic is saying it sounds like the HPFPs are the problem since the sound comes on throttle and only on idle. -Finally, this can be due to cp pistons gap vs oem ones. This one is a more focused question to the people who got their engine rebuilt, do you have the same sound? I will try to add a video later on but it's very hard to distinguish the sound on it. Sorry for the long post but I just don't want to spend money on parts which aren't problematic meanwhile this may be an impossible issue to solve.(piston gap) |
04-01-2019, 03:17 PM | #2 |
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I know what kind of sound you're talking about... it often gets associated with common DI and HPFP noise, but if yours are any louder, then it could very well be the valve lifters, or valvetronic related. Definitely get them checked as soon as possible, because you don't want this kind of issue to develop.
Also try switching to a 40w oil to see if the sound goes away a bit. |
04-01-2019, 04:12 PM | #3 | |
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Engine rebuilt, new weird sound
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04-01-2019, 04:26 PM | #4 | |
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I've seen a handful of engine build list, and most of them stick to CP Pistons and Carrillo Rods, with no mention of aftermarket valves or lifters. In fact, both Carbahn and Ghassan offer the same options for their rebuilt S55 longblocks. It may have been a good idea to change the lifters while you had the engine rebuilt... that may have saved you from having to deal with this issue now. |
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04-01-2019, 04:44 PM | #5 |
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Could be oil squirters contacting the piston skirt or connecting rod, larger piston to wall clearance, or a bunch of other things.
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04-01-2019, 05:54 PM | #6 |
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I learned to mark everything and put everything back in the same position when doing a rebuild. Was this done with the valvetrain components? If it’s clearance related, do you hear difference when cold vs operating temperature? Issue might still be there at higher rpm but not audible because of shift in frequency. I would inspect everything with a boroscope.
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04-01-2019, 05:55 PM | #7 |
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04-01-2019, 05:58 PM | #8 | |
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04-01-2019, 10:48 PM | #10 |
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Having built a few of these, pushing them to over 900+ HP, I'd presume this is typical "built engine" noise.
Slightly more loose PTW and Oil clearances. Speak with your builder to understand the specs/tolerance that they've setup in the engine. ~Anthony |
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04-02-2019, 01:18 AM | #11 |
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But if it was the ptw, sound should go away when it gets warmer, right?
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04-02-2019, 07:05 AM | #12 |
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Not always.
If they've setup/specified a unique PTW clearance it could have lightly audible piston slap until power pulls are done and the engine is hot. Most CP pistons are made with 2618-T61. This material is more ductile, which allows it to resist cracking, and can tolerate high cylinder temperatures. Because it has a low silicon content, it also requires a larger PTWC. Its the best material for high power/boost applications. Again, speak with your builder to know what they've spec'd. ~Anthony |
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10-25-2023, 03:15 PM | #13 | |
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11-03-2023, 11:45 AM | #14 |
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Nothing, as I reached to Carillo they informed me that they sound like a bit knocking because they’re racing pistons and material difference between the original pistons are the reason why the car is sounding different..
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11-03-2023, 02:14 PM | #15 |
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ok. so you still have the same noise ! is it in all rpm ? or up to a point ?
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11-03-2023, 05:11 PM | #16 |
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