How To Remove Exhaust Manifold Studs

| How-To - Engine and Drivetrain

How to Remove Cleaved Exhaust Manifold Bolts: Drilling vs Welding

How practice you remove a broken exhaust manifold bolt from an aluminum head?

If you use a gasoline-powered V-viii pickup or SUV to tow a trailer, chances are y'all're going to eventually have an exhaust leak caused by broken manifold bolts or studs. We accept a 2004 Contrivance Durango with the aluminum-head five.7L Hemi that nosotros purchased brand new. In addition to regular commuting duties we oftentimes employ the fiddling workhorse SUV to tow a six,500-pound wakeboard boat or a Jeep/trailer combo of similar weight. The rider and commuter frazzle manifold bolts let become at roughly seventy,000 miles and we had them replaced by the dealership under warranty. Then, at near 188,000 miles the driver-side exhaust studs snapped. We got really lucky and those particular studs snapped off with about 1-inch of exposed stud shaft sticking out of the cylinder caput. Furthermore, the broken studs were just in finger-tight, so nosotros were able to but spin them out and supercede the gasket and bolts with lilliputian drama. Most recently at 262,000 miles the rider side started the telltale "tick, tick tick" when the engine was cold. Once the vehicle was driven a short altitude, the manifolds swelled upwards and the tick was mitigated, but we figured nosotros'd highlight the fix earlier it got too astringent.

Why You Should Gear up an Frazzle Leak

Under extreme apply like towing heavy loads, the exhaust manifolds can become from normal operating temperature to cherry red in a matter of seconds. That rapid oestrus causes the exhaust manifold textile to expand, which puts a tremendous strain on the bolts and/or studs belongings the manifolds to the cylinder heads. After hundreds of expansion and contraction cycles, the studs or bolts finally fail. It'southward not too different from bending a newspaper clip back and forth. Eventually it'south gonna come autonomously in your hands. With merely part of the manifold cinched tightly to the engine cylinder caput, the exhaust gasket volition blow out, not only allowing exhaust gases to escape, simply possibly allowing air to enter the exhaust stream, throwing off the O2 sensor'south readings. If the O2 sensor thinks the engine is running leaner than it should, it will trigger more than fuel to exist dumped into the engine, potentially causing harm to the catalytic converter(s). Also, the exhaust manifolds tin expand and contract unevenly, which could crusade the cast iron to scissure, compounding the incorrect O2 sensor readings, not to mention making the abrasive exhaust leak sound worse.

Getting Admission to the Engine

Every vehicle is different, but on this Dodge Durango it's easiest to gain access to the frazzle manifolds by jacking upwards the vehicle, removing the front tire, and and so taking out the inner fender liner. We put a jackstand securely under the framerail and then got to work. Once we had access to the manifold we soaked the bolts with penetrating oil to help them come up out without snapping. If you live in an area that uses route salt or you experience a lot of rain, snowfall, or sea spray, you'll probably want to devote a couple days to soaking the bolts repeatedly with penetrating lube. This vehicle has been in SoCal its entire life so we just let them soak for a couple hours before proceeding.

Remove the wheel and tire and then the inner fender liner to proceeds admission to the exhaust manifolds.

Inspect the bolts and exhaust system for obvious harm before proceeding. If you need more than parts, it's best to order before you tear your vehicle down.

Our manifold collectors employ captured nuts that had rusted apart.

Apply a quality penetrating spray to soak all of the frazzle bolts before you endeavour to remove them. It will help prevent further snapping and more piece of work.

Removing the Manifold

In our instance, the Hemi exhaust manifolds use iv studs and five bolts. The studs hold the estrus shield in place. All of our bolts came out in one piece, but two of our studs had snapped. Furthermore, two of the nuts that held the heat shield on had seized to the studs and wouldn't spin. Normally, you can't just spin the studs out with the heat shield in identify, just in our case one of the seized stud nuts was on i of the snapped studs and the other loosened merely enough before refusing to budge that information technology created enough slack to permit the stud to spin out without destroying the heat shield. We were able to pull the heat shield free and so remove the studs on the ground without hurting annihilation. All of the exhaust manifold bolts came out without issue, but the collector basics that had rotted away were a problem. Miraculously, we were able to get a pair of vise-grip pliers on the nut and concur it tight enough to remove the manifold collector bolts. With all the bolts removed, the manifold and gasket were removed, exposing the broken studs in the cylinder head.

The snapped stud (foreground) obviously pulled right out of the manifold. The rear stud spun out afterwards we managed to loosen the estrus shield, retaining nut enough to allow it to spin on the heat shield.

With the rut shield removed we took all but one manifold commodities out before tackling the collector-to-downpipe bolts.

The collector bolt originally featured a captured nut that wouldn't spin, but the textile had rotted away. Thankfully we were able to get a pair of regular vise-grip pliers on the outer nut. A pair of needle-nose vise-grip pliers fit between the collector and engine cake on the inside bolt. Nosotros used regular nuts when reassembling.

Extracting a Broken Bolt from Cylinder Caput

Depending on where the stud or nut breaks determines how lucky yous are. Ideally, the stud or commodities volition break with a bunch of shaft exposed that you can go a set of pliers on to spin information technology costless. If not and it'southward cleaved off affluent, nosotros've had success in some cases of carefully using a sharp punch or chisel to carefully spin the stud out. Nevertheless, chances are the bolt or stud volition either exist snapped off deep in the threads or will be seized and won't want to come out. In those cases you have two options: drill information technology out or weld a nut onto the cleaved portion and spin it out.

This stud had snapped off most inch beneath the surface of the cylinder head and wouldn't spin with a sharp punch.

Drilling can be a unsafe and unsuccessful endeavor. The thought is you lot beginning drilling in the direct center of the bolt and then footstep up the drill size in increasingly larger increments until you're near at the threads. Then, you can use an extractor to spin the remaining bolt out. Nosotros've done this in the past, just information technology'due south nerve-racking because if yous pause off a drill chip or hardened extractor inside the head there'southward virtually no getting it out. We contemplated drilling our stud out, simply the fact that we have aluminum cylinder heads and this vehicle had a control arm smack in the mode of the drill, we opted for the welding route.

Fifty-fifty with a tight 90-degree drill, an upper control arm prevented us from getting a clean angle with the drill extractor on the cleaved stud.

Your other option when all else fails is welding a nut onto the end of the broken bolt or stud and spinning information technology out. Not but will the welding give y'all a secure purchase with which to wrench or spin the cleaved shank out, but the heat from the welding will help loosen any rust, antiseize, or other material that's helping prevent the broken shank from coming out. If you're working with atomic number 26 cylinder heads you lot need to be extremely conscientious to avoid actually welding the nut to the cylinder head or dissentious the threads. For this reason, it'due south commonly all-time to utilize a TIG welder. TIG welding is much more precise than MIG welding, but not everybody can do or has a TIG welding setup. Worst instance scenario there is y'all're removing your cylinder heads and taking them to a machine shop to have the stud extracted. Yet, most modern engines like the v.7L Hemi nosotros're dealing with have aluminum cylinder heads. With standard MIG or TIG welding, the steel welding wire won't stick to or even damage the aluminum of the cylinder head, allowing you relative safety while attempting to weld on a nut. We used a pair of needle olfactory organ pliers to hold a 3/8-inch nut over the hole containing our broken stud. Because the shank was roughly inch down in the hole, we used a relatively high wire speed to help fill up the gap and allow 'er rip. With a nut securely welded to the broken stud, the remaining portion spun right out with no damage.

We fastened our welding ground to the engine and used needle olfactory organ pliers to hold a iii/eight-inch nut against the head over the hold containing the cleaved stud shank.

With a relatively high wire speed, we welded the nut onto the cleaved shank and spun it out of the head.

You lot tin can see the gap betwixt the portion of the broken stud and the nut.

Using a relatively low welding heat, the aluminum of the cylinder head remains completely undamaged class the welding process.

New Exhaust Gaskets and Studs and Reassembly

Thankfully, after a careful inspection we found no cracks in our manufactory exhaust manifold. You don't desire to cheap out and get junior parts when information technology'due south time to reassemble. For our 2004 Hemi we went with a manufactory Mopar frazzle manifold gasket and a fix of new FelPro studs that we purchased from Superlative Racing. The FelPro studs came with a blue blanket for corrosion resistance and included thread locker on the threads. It seems the gasket design has inverse over time, so after verifying the port sizes on the gasket were the same equally the original, we practical some antiseize to the bolt threads and got ready to reinstall the manifold. Two of the manifold bolt holes are notched to allow the manifold to slide on. This allows yous to keep the manifold gasket on the caput while yous dispense the heavy manifold into identify. In our example, we had enough access where this wasn't really an issue, and then we assembled both gasket and manifold together, making sure to put studs in the correct holes to have the heat shield. After getting the bolts finger-tight nosotros broke out the torque wrench and over 3 passes torqued the manifold bolts and studs in the right blueprint (we found ours online) to the correct 18-lb-ft value for our engine. After the manifold was torqued to the head, we installed some new Class 8 bolts, lock washers, and nuts and tightened downwardly the downtube collectors to the manifold. Later a examination fire to verify there were no leaks we buttoned upward the inner liner, reinstalled the wheel, and enjoyed the relative sound of silence when firing this engine up when cold.

We cleaned and wiped the gasket surfaces of both the cylinder head and frazzle manifold to ensure a leak-gratis seal.

A manufacturing plant Mopar gasket and FelPro hardware kit from Summit Racing were the merely parts we needed. Grand total for this job came in at $75.39.

The FelPro hardware kit is $xxx.99 through Tiptop Racing, only its high quality with a corrosion-resistant coating fits perfectly.

We threaded i commodities through the gasket into the caput to hold the gasket in identify while nosotros got the manifold ready.

Make sure the bolt hole you utilise corresponds with the slotted hole in the manifold and so yous can just slide it into identify.

Nosotros torqued the exhaust bolts to xviii lb-ft per the manufacturer's blueprint, which we found through an online service manual. If you lot can't find yours, merely commencement in the center and alternate crisscross—bottom, top, side, side—until you've done all of them.

With the rut shield and new collector-to-manifold bolts installed this chore is a wrap.

Source: https://www.motortrend.com/how-to/removing-broken-bolt-from-cylinder-head/

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