Exhaust manifold broken bolt replacement....... 2012 Dodge Ram

brino

brino

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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.

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.

The noise really doesn't concern me too much, but the exhaust smell in the vehicle does.
It's not too bad when I'm moving, but during warm-up and sitting at lights it is very noticeable.
It's also noisy enough that I cannot really tell if the drivers side also needs attention.
The drivers side is slight more work with the steering linkage in the way.

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).
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.

....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?
Some concerns:
More manifold bolts could break in the next few months.
Extra heat in the engine bay affecting plastics, wire insulation, etc.
Lower backpressure to the affected cylinders.
I could live with reduced mileage for a couple months......
I could probably work-around the exhaust in the cab.....

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.

Once I get a manifold off I intend to put the mating face on the surface plate and test for rocking, gaps, etc.
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?
I do have a small heat-treat oven, but don't know if the manifolds would fit.

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.

I intend to (over) use a high-temp, copper-based anti-seize on all the bolts.

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.

Thanks for any feedback!
Brian

By the way, we need a forum for regular "Automotive Stuff" (not just classic cars, rockets, boats, etc.)
 
A few thoughts...

As the exhaust gas leaks between the head and manifold, many times it 'erodes' the cast iron away... I've seen them eroded way too much to resurface. This would mean a new manifold.

Surfacing with a flycutter may be an option if you can get it set up on the mill and figure out how to hold it level. The fixturing is usually the biggest issue.

Being in an aluminum head, removing the bolts will likely depend on whether the factory used antisieze... and used enough. And whether the antisieze has survived the last 11 years.

If the bolts do come out, there is a possibility that the aluminum threads will be destroyed in the process. You may want to have a helicoil kit handy before starting.

One trick I have learned removing broken studs is to heat the stud red hot and spray it with Kroil while red... the Kroil cools (and shrinks) the stud quickly, pulling the oil into any resulting cracks between the stud and casting.

Good luck...

-Bear
 
brino said:
....and of course whatever I do is outside in January in Canada....
Click to expand...
Sounds like you are already loaded for bear Brian and on the right track. Outside in January in Canada, yeah, I’d wait. I last had a manifold bolt break I put it off because it was middle of summer and 110f outside and waited for a cool spell. You probably know this but I’ll bet dollars to donuts the broken one will come out easy but one or two way in the back will break and be a mess. Best of luck.
 
Doh! Sorry, you know I meant it as a compliment!

Yeah too hot and ya got sweat in your eyes, too cold and you can’t feel what you’re doing. If I have to I’ll take sweat. Too cold my hands always ended up looking like I’d stuck them in a shredder.
 
I don’t envy you @brino , broken exhaust bolts are a PITA, especially in aluminum.
If you are lucky enough to have part of the bolt protruding , sometimes you can weld a nut to it in situ and the heat from the welding process will ease the extraction.
Otherwise you are looking for a fun filled process of drilling and taping holes.
Removal of the heads is the easiest way to ensure that you can complete the job without much interference from the engine compartment constraints, but that does entail more work than I’d want to do outside in Canukistan (AVE reference) in January.
I would wholeheartedly endorse decking the exhaust manifold and (lesser) the exhaust deck of the head-
at least check flatness with a straightedge or blue it up on the surface plate to see how far off it is.

A small propane torch would be helpful. Heat up the bolts that aren’t stuck to make the job easier

I wish I was closer to lend a hand
 
"Exhaust smell in cab" !??
Regardless that it's winter, you had better drive with enough through ventilation that did not start out in the engine area..
The toxic that is in exhaust smell is CO, which kills!
The other stuff you can smell will seem to be "not so bad" after some minutes, enough to fool you.
In an industry where they seek to save a cent or two per vehicle on every part, there is a reason so much is spent in ducting the exhaust to some place out the rear, besides mounting the silencing bits.
 
One thing I learned from owning my repair shop was what jobs I'd want to do myself and which I'd farm out to someone else. I know I've made the right choice when the shop I took my car or truck to calls to let me know how much of a PITA the job is.

For $1500 - 2000 I'd probably farm that one out and stay warm in my shop making chips.

When my dad was a young man he crashed his hot rod (Ford w/Cadillac motor) into a telephone pole and nearly died. He blames that one on an exhaust leak so be careful putting the repair off. It's not likely to get better on it's own either.

Not sure what your personal finances are like, or what condition the truck is in, but a 12-year-old truck in Michigan is pretty much scrap metal.

John
 
You gotta fix it. Soon. Your "exhaust smell" isn't just from the leak, it's from the seriously over-rich fuel mixture. For every shot of exhaust leaking out, there is a nearly equal shot of raw air leaking in on the negative pulse. This will cause the O2 sensor to read false lean, jacking the fuel mixture way rich on that bank. Codes, cat damage, washed out rings, etc.

But don't worry. As a ex-employee once said, Chrysler designs some really good engines.... except for the ones ending in "7".
 
As someone who did this for many years at Ford dealers, be aware that the stud/bolt maybe SS. On Fords they are.
If there is mat'l above the head surface, try welding a nut on.
If it is flush , try to get a center mark for drilling.
If it is below, make a drill bushing to fit the manifold hole to get centered or buy an available drill guide that fits the tread of the bolt.
Drill through the broken section, get some penetrant behind the bolt, use heat to get the penetrant to weep into the threads.
 
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