Hi Gang,
I'm looking for a little advice from those that have "been there and done that".
The patient is a 2012 Dodge Ram 1500.
I had been hoping that the exhaust noise I started to hear was the (fairly accessible) joint between down pipes (with the cat converters) and the extension pipe back to the muffler. I had done a clamp replacement there previously, but no, the leak is near the engine. The manifold to converter joints also look okay and are not "puffing".
From my research on "the net" it is normally broken bolts (M8x1.25), and not actually cracked manifolds.
Apparently this is very common on this vehicle and due to the manifolds changing shape during hot/cold cycles.
I have replacement gaskets in hand, and the bolts should be here today.
Sounds about like any modern pickup truck. Too many horsepowers, and not enough engine.
Next I need to check the condition of the manifolds.
I tried looking from below, but nothing was visible/accessible.
Last night I got the passenger side up on blocks, wheel off, fender liner off, and then heat shield off for my first good look.
On this side I see one broken bolt; the top one at the back, oddly the most accessible one.
Of course who knows how many other bolts will break during removal.
These are steel bolts into the aluminum head with cast-iron manifolds.
So far the manifold looks okay.
When we get after rotten manifolds at work, step one is a flat chisel in the air hammer. Get the low side (towards the manifold) of one flat of each bolt/nut and drive in a little, make the stud/bolt "move sideways" just a bit. Not a lot, just enough to see. But low on the hex, you still wanna get a wrench on it.
That one you can see/get to- DO NOT try to fix that one "through" the manifold. Your retorqing of a new bolt is gonna capture a different part of the manifold from what it was previously used to. You'll have a new stud broken about every week if you try to patch up one at a time. You said you had the gaskets, and you said it cleared up as you drive, so that would probably stop the cold leak, for a very short time.... When you stumble on that advice don't take it. Take the manifold off, no matter what.
I have not taken it in for a quote, but from what I see online, this would likely be $1500-$2000 to have done (assuming both sides).
It's broken rusty things. There are no quotes, and there are no estimates. If you want to know what it'll cost at retail, and somebody gives you a quote for anything less than two cylinder heads, two manifolds, and a Y pipe.... It's not a firm quote anyhow. Although odds are it'll be a lot less.
However, in true HM style and inline with my sig line I'd rather do this myself.
Plus I'd rather spend money on tools I can keep after this job is complete.
I have ordered a Milwaukee cordless right-angle drill, but it won't be here until next week.
I also have new stud remover tool that was recommended in one of the online references.
First, try to unscrew all the bolts/nuts/studs that you hammered on sideways. We use the air hammer, but a blunt punch and a stubby sledge hammer/drilling hammer/whatever you can get your hands on works too.... You'll find that the unbroken ones have real good odds of coming out that way.
99 times out of a hundred, the bolt is broken within a quarter inch of the surface, or a little above it. Set a nut over the stud/bolt, and plug weld it there. (The weld won't stick to aluminum). Once it's cooled to 3 mississippis on bare fingers, gently work it back and forth to free the bolt. Don't plastically deform it, just wiggle back and forth, but don't get greedy. You'll know when you can go ahead and turn it. Save the drilling for a last resort. It's stuck by corrosion and galvanic metal disfunction, so you're not gonna "release it" by hollowing it out. You're going to have to not miss dead center. And screw extractors just exacerbate the problem. You will, in almost all cases, have to install new threads. That's not a bad thing at all, it's a simple, sound, driveway capable repair, but if you have an off center hole, you're not gonna recover it with the head still on the engine. And/or you are tallented at such upside down and backwards things while stuffing yourself through a wheel well hole, there are some jigs out there for "most" engines that have a high failure rate, that can line you up based on a couple of other neighboring holes. They still take a little care and a steady hand to make 'em work, but they are out there if you get stuck. Find 'em if you need one.
....and of course whatever I do is outside in January in Canada....
Q1) Can I just stop now and put up with it until warmer weather?
What additional damage could happen?
I honestly don't know if you have MLS or graphited gaskets. MLS "might" buy you some time, but if the leak is passing between the gasket and the aluminum head, it's erroding the head's gasketing surface. If that's small, it's recoverable, but it's a big deal.
More manifold bolts could break in the next few months.
Most common is for one (maybe two) to break off at or near one end, followed by the other end doing the same. At that point, the expansion and contraction is not constrained over such a long distance, the combined stresses get a lot less, and the "middle" bolts are a lot more reliable. Nothing's gonna fall off and kill the family in the mini van behind you. But indeed, the bolts will continue to fail.
Extra heat in the engine bay affecting plastics, wire insulation, etc.
It's gonna be pretty bad before that's an issue. It's a diffused leak, with a lot less volume than it actually sounds like. No worries on that count.
Lower backpressure to the affected cylinders.
Not even close. Forgetting the fact that the ECM is correcting each cylinder individually, in real time, the volume lost isn't enough to be tangible in any way. No worries on that count.
I could probably work-around the exhaust in the cab.....
That won't bother you a bit... You'll just fall asleep peacefully before the real trouble starts.... Serious repercussions for a mis guess here on what's worked-around enough to be a work-around. Thinking cap on, and chin strap fastened so it doesn't fall off...
Since the sound is worse at start up (cold) than when it warms up, I assume that the manifold is still changing shape with temperature.
Therefore simply (yeah, right!) replacing the manifold bolts would likely lead to the same failure again, but likely years down the road.
Yes, the manifold changes shape a lot. The outside edge (farthest from the ports) runs crazy hot compared to the inside face based on the gas flow, and there's some heat sink effect from the engine block as well, although that's more with MLS gaskets, which again, I don't know if that's what you have. What happens is it spends so much time at crazy hot temperatures, "wanting to be shape changed" into a U, with the center pulled away from the head, that it kind of adopts a new shape. Then when you shut the engine off, the middle settles down, and the ends want to lift. When you actually remove it, you're probably going to find that it's all over the place, and not really that flat at all. You'll also find that if you cut it, you just start the process over again, you're going to force it to re-shape it's self a second time. Cracks are very common in original manifolds, and almost a guarantee in reused manifolds, surfaced or not.
Once I get a manifold off I intend to put the mating face on the surface plate and test for rocking, gaps, etc.
I wouldn't treat a surface plate like that without a good reason. There's a good chance you'll find what you're looking for just by sighting down the manifold, otherwise a good steel rule, or carpenter's square is all you're gonna need.
Q2) Would setting it up on the mill and fly-cutting the sealing face help at all if it is still warping?
Is there a heat-treat cycle that they could be run thru to normalize the casting?
The bolts and the manifold both fail for the same reason. They flex back and forth every time the engine load changes. Rusty as they are, it's fatigue, not rust that kills them. I'm not sure that normalizing the casting will address that? Maybe. Never heard of that being done, but that one's not one I can speak to.
I could get replacement manifolds, but there's really no guarantee that they would be any better (flatter and less likely to warp) than the ones currently on the engine.
There's no guarantees either way..... The originals have used up the best of their life, and the aftermarket ones were made to a price point. New OE, if it's available, will be the best dollars per mile option, but even those these days are designed to last "long enough".
I intend to (over) use a high-temp, copper-based anti-seize on all the bolts.
No. Nickel. Period. Unless you've got stainless bolts. Then use nickle there too, but do it with a big exclamation point. It's chemical soup when you get into dissimilar metals and heat. Nickel will not damage the head in the worst case scenerio, and will still release the bolt/stud.
When you apply it (or any other carefully chosen anti-seize), toss out what anybody's told you about putting it on like somebody else was paying for it. It doesn't work that way. A light EVEN coat over the male threads in a case like this is overkill. Basically as much as you can possibly work into the threads WITHOUT pushing up a "bead" of it when you screw it into the female threads. That's way more than enough for it to do it's magic. It's not "grease", it's chemical soup. It's just gotta be there.
I have all the various "rusted bolt" procedures in mind; penetrating oil, stud remover, oxy-actylene for heat, left-handed drill bits, welding on washer/nut, etc.
I don't think I'll bother with an easy-out ever again, I don't believe they have ever worked for me.
I see you're ahead of me on the easy outs.. There's a heckuva good start to an uneventful process. Don't spray penetrating oil on this stuff. Slippery isn't the problem here. The only oil that's gonna make your day better is if you end up drilling a bolt out, which of course is best to avoid. Here's another tip. The welded nut (you're ahead of me again...) will turn out bolts with pretty surprising success. The concentrated heat from that (inside the oxide insulation layer that slows transfer to the aluminum), will break loose ANYTHING that the lefty will get out. A lefty is more work, more awkward, more risks for "escalation", and less successful overall. I know you're not in ideal conditions, but if there's any practicable way to make the welder the first go-to, your success rate and time invested are both gonna be better off.
Three more things-
First, and my my go-to for this is Ford, with the same very common 8-1.25 manifold hardware. The 6.0 diesel (and some others) uses a spacer, 3C3Z-9A461-AA, to artificially lengthen the hardware. More metal to take more "stretch" when bringing to torque, more available "stretch distance" to keep the joint tight at it's "smallest", and not reach plastic deformation at it's "largest", and dividing the back and forth rocking influence over a longer distance, minimizing fatigue. Adjust the hardware you chose accordingly, and torque the assembly to your engine's manual, not Ford's. (Yeah, you can make those, but they're under two bucks each, I'm not sure that effort would pay for it's self). That was (and to my knowledge still is) the cheapest way to put an OE quality part in your hand, although there are a LOT of applications for these from a lot of makers.
Second, Do you install bolts or do you install studs and nuts? My answer is yes. They're ALL gonna work equally well over their lifetime, and they're all gonna be the same PITA the next time around, and stud OR nut, nobody in their right mind is going to reuse that hardware, so it's ALL coming back out. My personal choice when I'm billing by the hour (or stocking a shelf) is to plan on a stud at one location on one port on each end of a manifold. (One piece ones anyhow), and bolts for the rest. Adjusted for access if needed, if it's gotta roll in there a funny way. The goal is to use the cheapest, quickest hardware that is equally durable and equally servicable at a later date, keeping parts and labor down, with the two studs to hang the manifold and the gasket from while the rest of them get started. (Literally, at retail, those two studs and nuts will cost more than the other forteen bolts did...)
Third, Stainless steel or "regular" hardware? Slight preference for the "regular" here. Stainless hardware (which you might already have) can be a genuine bugger to work with when it gets stuck (and it DOES get stuck). Either way, like I say, it's not so much rust as it is the heat and movement that makes these break. The stainless will be prettier, but it still breaks. You might get one or two extra "survivors" to not break on the next go-round, but a bog standard two minute bolt extraction might quick turn into an hour. (Or for driveway work, I'm guilty of that, multiply both of those times by ten...). So really, which ever one lets you sleep better will probably be best, because they seem to average out to about the same.
