Fuel Quality connected to engine failure

[A4Owner]

I'm an Audi owner looking at the Ram 1500. I like the 5.7 engine for my own reasons but what I learned was that these engines were prone to some type of failure at 100,00km where I believe the exhaust manifold became detached from the engine block causing a chattering sound. First off is this even correct? Does this happen on Gen 5s? Secondly, if this is even an issue is it related to fuel quality? So one Youtuber claims to link this issue to lower grade fuel use. The next question is aren't these things rated for use of mid grade fuel which I think is like what 90 octane? So if you use 90 through out the life of the truck wouldn't this issue be a non issue? Anyways not sure if this makes any sense of if any of you Senior Ram owners could weigh in that would be great...oh and happy to answer any Audi questions...great cars...just not the size of a mountain like these behemoths.

 

[Fatherof3]

I'm an Audi owner looking at the Ram 1500. I like the 5.7 engine for my own reasons but what I learned was that these engines were prone to some type of failure at 100,00km where I believe the exhaust manifold became detached from the engine block causing a chattering sound. First off is this even correct? Does this happen on Gen 5s? Secondly, if this is even an issue is it related to fuel quality? So one Youtuber claims to link this issue to lower grade fuel use. The next question is aren't these things rated for use of mid grade fuel which I think is like what 90 octane? So if you use 90 through out the life of the truck wouldn't this issue be a non issue? Anyways not sure if this makes any sense of if any of you Senior Ram owners could weigh in that would be great...oh and happy to answer any Audi questions...great cars...just not the size of a mountain like these behemoths.

There's 2 things that "can" happen to the HEMI . 1 is the exhaust manifold bolts breaking which causes the HEMI tick , this will quiet down once the engine warms up a bit ( usually around 30 seconds )
2 is the lifter / cam tick which does not go away . The exhaust manifold is the more common of the two . That doesn't mean they all will have a problem as most don't but they certainly aren't unheard of .
I don't think the octane of the fuel makes any difference.

 

[A4Owner]

Ok that's kind of what I thought. So this exhaust manifold coming undone thing is more what the fact that you have a steel bolt and an aluminum manifold interacting and when you get moisture in there it corrodes? So could I not simply solve this issue by retrofitting a more suitable bolt on or is it not that simple? And then just back on fuel. So what is the official fuel grade required for this engine? And as a follow up is there any benefit to using a higher grade of fuel like 93 and likewise any drawbacks/dangers of using lower grade fuel. I'm the type of guy where I really try to stick with the exact same fuel and oil for the life of the vehicle...and with Audi you have these high pressure fuel injectors that do require (not just recommend) really good fuel. I personally don't care how much fuel this monster drinks now b/c I'm not yet an owner but I gotta figure the Ram will drink SUBSTANTIALLY more fuel than my car. Correct me if I am wrong but the Hemi V8 is a normally aspirated push rod motor with minimal cams and an overall simple design so no variable valve stuff right? Its just your typical big honking American V8?

 

[Andymax]

If I'm not mistaken, the bolt breaking is primarily on gen4 trucks. Then mopar "solved the problem" and put stronger bolts in the gen5's, BUT they didn't change the manifold design, so now it's more common on gen5 motors that the manifold itself is cracking. Either way, this issue is covered under powertrain warranty and is still relatively uncommon.

Otherwise, your assessment of the 5.7 Hemi is pretty accurate, but missing the fact that it is an otherwise very reliable, and relatively efficient V8. It also does not require any premium fuel, just wasted money if that's what you buy.

 

[A4Owner]

I agree with the fuel comment...use what it says to use in the manual period. But as a follow up...how hard would it be for me to bolt on I guess new or better designed bolts to the exhaust manifold if I cross the warranty? Assume this is a matter of getting underneath it and having a flexible socket/ratchet set? Like the thing with Audi is there is sooo little room in the engine Bay that at this point I'm use to working in really tight areas. From what I can tell lots of space under these things no?

 

[Eighty]

Here's what the user's manual says:

 

[Andymax]

^^^^ and that is exactly why I use 87. I drive a LOT compared to most and I have laser focus on fuel economy always. In my experience there ain't no way any "optimum performance" and resulting increase in fuel economy using 89 would outweigh the extra cost. We've had two hemis well over 200K, with never a drop of anything but 87...YMMV.

 

[Fatherof3]

I agree with the fuel comment...use what it says to use in the manual period. But as a follow up...how hard would it be for me to bolt on I guess new or better designed bolts to the exhaust manifold if I cross the warranty? Assume this is a matter of getting underneath it and having a flexible socket/ratchet set? Like the thing with Audi is there is sooo little room in the engine Bay that at this point I'm use to working in really tight areas. From what I can tell lots of space under these things no?

I've seen videos of people getting at the exhaust manifold bolts through the wheel wells .

 

[BigEarl62]

A4Owner, may we ask where you will be enjoying this Ram 1500? My guess while probably wrong is Sweden

 

[HemiDude]

The Ram 5.7 does have VVT, by the way. And I have seen two problems with the exhaust manifolds: bolts breaking and manifolds cracking. I'm sure it is related to different expansion rates of the cast manifolds, aluminum heads, and associated fasteners. One thing to consider if you replace the factory fasteners but keep the factory manifolds, is that stronger bolts may just pull out of the heads rather than breaking