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Discussion Starter #1
I know this is a known “thing” already, but just in case any of you haven’t heard already: the intake bolts on your 5.7L have a tendency to loosen up over time/miles and need to be re-torqued periodically.

My neighbor bought a used Charger with 89K miles on its 5.7L, and we were going over it to assess the condition of various items when the intake bolt thing crossed my mind. So I grabbed an 8mm socket and my torque wrench to check them, and sure enough every single one was waaay loose. All needed several turns of the torque wrench to get back to 105 in/lbs like they’re supposed to be.

If your 5.7L has >50K miles, you should definitely check ‘em.

If your 5.7L has anywhere close to 100K miles (especially if more), you WILL need to tighten them back down. (okay, there’s a possibility you won’t, but you’ll be the exception that proves the rule if you don’t have to!)

Bolts are 8mm and located just inside fuel rails along upper intake plenum. There are 10 of them IIRC.

Torque spec is 105 in/lbs if using a 1/4” torque wrench or ~8 ft/lbs if using a 3/8” drive torque wrench.

Also, you will need an extension for the torque wrench and socket to get down onto the bolts and clear the fuel rails so the wrench can ratchet freely.

Nuke
 

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My bolts were loose at ~18,000 miles, which is when I retorqued them but a couple months later they were loose. IMO if your bolts are loose, take off the intake, put on new intake gaskets, apply loctite to the bolt threads and install the intake. Otherwise the bolts will eventually loosen again.

Now that I have the supercharger...no more loosening bolts. :)

Also DO NOT torque the throttle body bolts to the same torque as the intake bolts otherwise you will strip the plastic intake threads.
 

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I haven't checked mine in awhile, thanks!
 

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Good info and reminder, I actually didn't know this. I will be using my 07 Charger RT for my winter car in a few months, and I'll be sure to do this.
 

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Discussion Starter #5
My bolts were loose at ~18,000 miles, which is when I retorqued them but a couple months later they were loose. IMO if your bolts are loose, take off the intake, put on new intake gaskets, apply loctite to the bolt threads and install the intake. Otherwise the bolts will eventually loosen again.

No that I have the supercharger...no more loosening bolts. :)

Also DO NOT torque the throttle body bolts to the same torque as the intake bolts otherwise you will strip the plastic intake threads.
speaking of removing the intake, i have been contemplating pulling mine off to see what it looks like on the inside (I'm thinking it's probably pretty grimy), but disconnecting that fuel line gives me pause. Does it require a special tool like one of those id have to borrow from AutoZone or can i get it disconnected without anything extra or special?
 

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Discussion Starter #6
I haven't checked mine in awhile, thanks!
i checked mine again too, and they were loose again as well. It's only been about 30K miles since i did it last, but sure enough, they weren't torqued to spec anymore.

they weren't as loose as the neighbor's car's, but loose enough...
 

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speaking of removing the intake, i have been contemplating pulling mine off to see what it looks like on the inside (I'm thinking it's probably pretty grimy), but disconnecting that fuel line gives me pause. Does it require a special tool like one of those id have to borrow from AutoZone or can i get it disconnected without anything extra or special?
I think my 2015 has the redundant latch single button type fitting which I don't recall needing a special tool. In fact, I looked on chilton and all the fuel line connections they show do not require a special tool. Funny thing is I own one of those fuel line disconnect tools and none of my vehicles need it (all are FCA). I have my OEM intake with <20kmiles on it and it looks pretty clean but I bet my JGC is coated with oil vapor. I should look into seeing if I can swap it on my JGC...I am pretty sure it is the same 5.7 manifold.
 

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This is a good reminder. I was getting rough idle around 60k miles.

Put the torque wrench on and they were at about 30 in/lb. went in sequence 3 times working my way up to 75 in/lb. I didnt know it was 105, i should go back over it once
 

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Discussion Starter #9
This is a good reminder. I was getting rough idle around 60k miles.

Put the torque wrench on and they were at about 30 in/lb. went in sequence 3 times working my way up to 75 in/lb. I didnt know it was 105, i should go back over it once
105 in/lbs is what i have from a chiltons manual. its possible the actual service manual has something diff, but honestly 105 seems to be the spec for so many of the 8mm bolts tightening into plastic on the engine, i saw no reason to doubt it for these.

if someone finds it is incorrect, please let me know and ill correct the original post
 

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105 in/lbs is what i have from a chiltons manual. its possible the actual service manual has something diff, but honestly 105 seems to be the spec for so many of the 8mm bolts tightening into plastic on the engine, i saw no reason to doubt it for these.

if someone finds it is incorrect, please let me know and ill correct the original post
I also just like to play the safe side, i think 75 in/lb is about 6 ft/lb, and given that these manifolds have a large history of cracking, i felt it was tight enough lmao. She gets a lot if heat here in CA and some of the vacuum lines already look dry under there.
 

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Completely forgot about this when I just recently picked up an 06’ Daytona. Went out today and retorqued them and they all needed about 3/4 turn.

Speaking of vacuum lines... you wouldn’t imagine that they could get this brittle but the pcv line broke off and crumbled in my hand when I went to put a catch can on the Daytona.


Sent from my iPhone using Tapatalk
 

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The 2015 FSM calls out 9 ft-lb (108 in-lb) for the 5.7 & 6.4 intake manifold bolts. The throttle body is shown below. Torque the bolts when engine is cold...not hot.
978407


978408
 

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I retorque mine after every oil change. They have backed off at least a 1/2 to full turn.
 

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When I took of my manifold to install the magnuson, I saw there was no hint of thread locker on the OEM manifold bolts. Since the manifold is a composite, thermal cycling seems to cause the bolts to loosen regularly. Rather than taking the entire manifold off to reapply thread locker, I guess one could back out the bolts one by one and use a long tube to apply thread locker in the threads. Applying to the bolt would result in the thread locker being wiped by the manifold as it a captured bolt design.

Now on my JGC, 108kmiles and the bolts are still tight with no signs of staining around the head/manifold connection.
 

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Discussion Starter #15
… Torque the bolts when engine is cold...not hot.
How cold are talking here? Like cold as my wife’s heart when I’m feeling low and in need of some reassurance??

Cause if I gotta chill the engine down to that temp, I’ll need to replace the M1 10w-30 I’m currently running in the sump.

That oil can handle down to 32F, but I doubt I could even start the engine with that oil chilled down as frigid as Mrs. Nuke’s sympathy after another of my speeding tickets that I need help paying the fine on... 🥶
 

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Low mileage 2013 RT. Had a rough idle a few months back at 35k miles and saw all the posts about the intake bolts. Sure enough, they were so loose that they all took a full turn to reach 105 in.lbs. Trouble is that at the next oil change they had backed out again and took 1/2 turn or so to get back to 105. Only question now is what threadlocker to use? Red is definitely out. Purple looks too light. But they're pretty small bolts and I'm paranoid that blue might be going too far. Opinions?
 

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Discussion Starter #18
I used the medium strength stuff from Harbor Freight (No. 42), but I’m not sure which color that translates to in the name brand stuff:

984550


So far it has done me well, haven’t had to retorque those bolts in 50K miles or so.
 

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Food for though here


Slapped a 6.4 manifold on my 5.7

Used blue permatex (gel type)

3 days after install bolts had backed out a good amount, took about 3-4 turns on each bolt. Very confused.

One thing to note, some bolts have to thread through the manifold, and others drop right down and start threading.

Going to check again this weekend, coming from a few LS guys apparently heat cycling the intake manifold and bolts backing out is pretty common.
 

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Yeah, I found applying loctite after threading the bolts through the manifold worked best to prevent the loctite from being wiped off. I also thought that all the bolts on the manifold are a capture design (i.e. they don't slide in and out of the manifold holes), at least that is what I found on my 5.7 stock manifold. I have seen some folk recommend putting loctite in the threads of the head as opposed to the bolt to ensure max coverage but I have always put it on the bolt thread with no issue.
 
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