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Question from someone who is far from an expert on this subject :
I noticed no one has suggested lock washers for this application. My uneducated guess is this has something to do with the intake being plastic. Just wondering why ?
 

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Your suggestion is a very good one if vibration is the reason this is happening but there's almost zero vibration in this situation. I honestly don't think the bolts are backing out, it could simply be the heat and cold, expansion and contraction. Which could be having an effect on the plastic intake manifold, and the sealing gaskets between the intake manifold and the heads. That's why what Johnnyreb is doing marking the bolts with a witness mark is important.



IMO, a plastic intake manifold was just another cheap solution Dodge chose to use on the 5.7L HEMI Challenger, they chose it because it was cheap to manufacture.

Just like the drug companies do when they market a new drug then many years down the road find out the side effects are hurting people and pull the drug from the market.

Meaning Dodge had no idea in the early installation days of plastic intake manifolds what effect heat and cold expansion was going to do to the plastic. If the 5.7L intake had been made of Aluminum this probably would not even be happening, but it is happening and been discovered not just on the Challenger, but all the 5.7L HEMIs being implanted in vehicles. Challengers, Chargers, Chryslers, Jeeps, Ram Trucks, you name it.

If the bolts themselves are not actually backing out but over time are still loosing torque value from the effect of expansion and contraction then Johnnyreb may be 100% correct and continuing torquing could eventually just crush the plastic bolt contact points.

Maybe changing checking the torque values to a yearly basis, possibly?

I'm thinking doing witness marks on mine as well, I believe that is a very good idea, at least then we can actually see if the bolts are backing out?
I just gave a professional solution that is used in race cars and aviation. BTW, there is always vibration if the engine is running.
 

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Discussion Starter #103
Question from someone who is far from an expert on this subject :
I noticed no one has suggested lock washers for this application. My uneducated guess is this has something to do with the intake being plastic. Just wondering why ?
OEM wise this is the type of bolt that is pre-fitted with a washer on it, the type you cannot get the washer back off of.

https://www.stevewhiteparts.com/oem-parts/mopar-intake-manifold-bolt-6509246aa/?c=Zz1lbmdpbmUmcz1lbmdpbmUtcGFydHMmaT1OVzExMjY1NSZyPTE5JmE9ZG9kZ2Umbz1jaGFsbGVuZ2VyJnk9MjAxNSZ0PXItdC1wbHVzJmU9NS03bC12OC1nYXM=

You almost have to damage the bolt threads to get that washer off the bolt to install a lock washer.
 

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Discussion Starter #104
I just gave a professional solution that is used in race cars and aviation. BTW, there is always vibration if the engine is running.
I was not discounting your suggestion I even seriously considered it today when I went out to mark my bolt heads with a witness mark, but even if you can find the bolts for this situation, where to anchor the wire would be a heck of a challenge.
 

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Discussion Starter #105 (Edited)
@Johnnyreb

I put silver paint pen marks on the bolts that I could actually get to, but I could not get to all of them.

I definitely got the outer front 2, and some of the interior bolts so I'll keep and eye on mine as well, to see if they turn away from the alignment marks.

Edit: Went back out this AM and got to all of them, I not only marked the bolt to washer alignment, but the washer to the plastic intake alignment. I honestly don't think the washer itself could actually move, but I marked it anyway.

Ry
 

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Discussion Starter #107 (Edited)
@MIDNITE RT

I love your sig, you have no idea how many times I've wished the same! :)

Edit: The bolt picture in the link actually has preinstalled thread locker on it.
 

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I'm not sure that is true. My '04 Durango has a 5.7 with a plastic manifold and 97,000 miles. I checked it and they are all at spec.
 

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We'll see what happens in 6 months. I can't predict what is going to happen, but for sure if those bolts move, Ry and I both will know it. If they do I will be going to a better thread locker. If they don't and they lose torque I will be putting on a different intake.

I'm with Ry, I think it was a money saver for Mopar that should come back to haunt them.

At the very least a metal sleeve should have been put in the bolt holes for the washers to lock against. I guess I could put those in myself but it wouldn't work the same as if they were molded in. More to come.:giggle:
 

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Discussion Starter #110 (Edited)
I'm not sure that is true. My '04 Durango has a 5.7 with a plastic manifold and 97,000 miles. I checked it and they are all at spec.
That's interesting, I wonder if sometime after 04 they changed the plastic composition, or something?

Only the manufacturing engineers would know that.

Visually, There is a difference from the earlier 5.7L intake manifold to what's bolted on my 2015.

https://www.amazon.com/05-06-CHRYSLER-INTAKE-MANIFOLD-FACTORY/dp/B00DUFW6PY

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I know this is dirty, but it is before I cleaned it up, this is just a visual difference of the years, nothing more, personally I like the looks of the earlier year 5.7L intake manifolds the top looks cleaner without those 2 formed ridges on top.

Dodge must have had some reason for changing the overall design.
 

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Discussion Starter #111
Sorry that was embarrasing this is what it looks like under the hood now.
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The picture below is one of the alignment marks.
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The picture below is the new Fastman throttle body.
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It's not the cleanest I've had it, but it's 50 times better than the picture in the previous post! Ry
 

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Discussion Starter #113 (Edited)
Since obviously Mopar puts thread locker compound on the brand new bolts and the Mopar bolts I have had to replace of a different grade and size also had thread locker pre-applied. It would make sense that the bolts factory installed would be the same, so along that thought line, if anyone intends to install thread locker compound it better be the MoparA Lock & Seal Adhesive, that Mopar requires on the previous page of Shop Service Manual pages regarding the intake manifold.

Most of us would just trust the Blue Loctite to do the job, but the Blue Loctite could have a reaction to what's been pre-applied to the bolt, which could be good, or very, very, bad, just something to consider.
 

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Since obviously Mopar puts thread locker compound on the brand new bolts and the Mopar bolts I have had to replace of a different grade and size also had thread locker pre-applied. It would make sense that the bolts factory installed would be the same, so along that thought line, if anyone intends to install thread locker compound it better be the MoparA Lock & Seal Adhesive, that Mopar requires on the previous page of Shop Service Manual pages regarding the intake manifold.

Most of us would just trust the Blue Loctite to do the job, but the Blue Loctite could have a reaction to what's been pre-applied to the bolt, which could be good, or very, very, bad, just something to consider.
I would agree with Ry's statement about the thread locker. As for the ribs on the top of the intake, my guess is it has to do with a rigidity issue which may be related to our problem.
 

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I was not discounting your suggestion I even seriously considered it today when I went out to mark my bolt heads with a witness mark, but even if you can find the bolts for this situation, where to anchor the wire would be a heck of a challenge.
Link the safety wire from bolt to bolt on each side.
 

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Discussion Starter #116
Checked yesterday after 13 days the bolts have not moved from the alignment marks.
 

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Discussion Starter #117
Update: 35 days since the alignment marks on the bolts, no movement at all on any of them.
 

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Hey everyone. It's been a while since I've been on here but I wanted to give an update from the manifold on my end. I've just rolled over another 5k on the Predator and since I initially inspected my manifold (all of my bolts were around 20 inch lbs) and retorqued them to the factory specs. After 5k miles, I checked them again and they were all around 70 inch lbs this time around. After reading this thread and seeing what everyone else has done and/or recommended, what's the actual consensus and what should I do to keep them at factory torque specs without potentially cracking the plastic manifold?
 

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Discussion Starter #120
Hey everyone. It's been a while since I've been on here but I wanted to give an update from the manifold on my end. I've just rolled over another 5k on the Predator and since I initially inspected my manifold (all of my bolts were around 20 inch lbs) and retorqued them to the factory specs. After 5k miles, I checked them again and they were all around 70 inch lbs this time around. After reading this thread and seeing what everyone else has done and/or recommended, what's the actual consensus and what should I do to keep them at factory torque specs without potentially cracking the plastic manifold?
That sounds similar to my discovery.

I would suggest torquing back to 108inlbs just one more time and stop, both Johnnyreb and I, have put indicator marks on our bolts to monitor if the bolts back out. If they are not backing out continuing to torque could possibly damage the plastic, at this point I do not know whether the torque value has changed or not, but I do know the bolts are exactly where they were the last time they were torqued to 108inlbs.

So possibly if the bolts do not move, but the torque value lessens, it has to be a combination of the plastic intake manifold and the intake manifold seals compressing. Which logically means if the bolts are staying static it's not going to get back as low as 20inlbs as was first discovered. Ry
 
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