How To Remove Broken Bolt From Exhaust Manifold

| How-To - Engine and Drivetrain

How to Remove Cleaved Exhaust Manifold Bolts: Drilling vs Welding

How practise you remove a broken exhaust manifold commodities from an aluminum head?

If you employ a gasoline-powered V-8 pickup or SUV to tow a trailer, chances are y'all're going to somewhen have an exhaust leak caused by cleaved manifold bolts or studs. We have a 2004 Dodge Durango with the aluminum-head 5.7L Hemi that we purchased brand new. In addition to regular commuting duties we ofttimes use the little workhorse SUV to tow a 6,500-pound wakeboard boat or a Jeep/trailer combo of like weight. The passenger and driver exhaust manifold bolts let get at roughly 70,000 miles and nosotros had them replaced by the dealership under warranty. And so, at about 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 head. Furthermore, the broken studs were only in finger-tight, so we were able to just spin them out and supplant the gasket and bolts with little drama. Most recently at 262,000 miles the passenger side started the telltale "tick, tick tick" when the engine was cold. One time the vehicle was driven a brusque distance, the manifolds swelled up and the tick was mitigated, but we figured we'd highlight the fix before information technology got too severe.

Why Yous Should Fix an Exhaust Leak

Nether extreme use similar towing heavy loads, the exhaust manifolds can get from normal operating temperature to cherry red in a matter of seconds. That rapid heat causes the exhaust manifold cloth to expand, which puts a tremendous strain on the bolts and/or studs holding the manifolds to the cylinder heads. After hundreds of expansion and contraction cycles, the studs or bolts finally fail. It's not too dissimilar from bending a paper prune back and forth. Eventually information technology's gonna come up apart in your hands. With only part of the manifold cinched tightly to the engine cylinder head, the frazzle gasket will blow out, not only allowing frazzle gases to escape, merely peradventure allowing air to enter the exhaust stream, throwing off the O2 sensor's readings. If the O2 sensor thinks the engine is running leaner than it should, it will trigger more than fuel to be dumped into the engine, potentially causing harm to the catalytic converter(s). As well, the exhaust manifolds can aggrandize and contract unevenly, which could cause the cast iron to cleft, compounding the incorrect O2 sensor readings, non to mention making the annoying exhaust leak sound worse.

Getting Access to the Engine

Every vehicle is different, just on this Contrivance Durango it's easiest to gain access to the exhaust manifolds by jacking up the vehicle, removing the forepart tire, and and then taking out the inner fender liner. We put a jackstand securely under the framerail and then got to work. One time we had access to the manifold we soaked the bolts with penetrating oil to help them come up out without snapping. If you alive in an expanse that uses road table salt or you experience a lot of rain, snow, or ocean 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 then we just permit them soak for a couple hours before proceeding.

Remove the wheel and tire then the inner fender liner to gain access to the exhaust manifolds.

Inspect the bolts and exhaust organization for obvious harm earlier proceeding. If you lot demand more parts, it'southward all-time to order before you tear your vehicle downward.

Our manifold collectors use captured nuts that had rusted apart.

Utilize a quality penetrating spray to soak all of the exhaust bolts before you try to remove them. It will assistance prevent further snapping and more work.

Removing the Manifold

In our example, the Hemi exhaust manifolds utilize 4 studs and five bolts. The studs hold the rut shield in place. All of our bolts came out in i piece, but 2 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. Unremarkably, you tin't just spin the studs out with the rut shield in identify, but in our case one of the seized stud nuts was on one of the snapped studs and the other loosened just enough before refusing to budge that information technology created enough slack to let the stud to spin out without destroying the rut shield. We were able to pull the heat shield gratis so remove the studs on the ground without hurting anything. All of the exhaust manifold bolts came out without upshot, but the collector nuts that had rotted away were a trouble. Miraculously, nosotros were able to get a pair of vise-grip pliers on the nut and hold it tight plenty 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) plain pulled right out of the manifold. The rear stud spun out after we managed to loosen the oestrus shield, retaining nut plenty to allow it to spin on the heat shield.

With the oestrus shield removed we took all only ane manifold bolt out before tackling the collector-to-downpipe bolts.

The collector bolt originally featured a captured nut that wouldn't spin, only the material had rotted away. Thankfully we were able to go 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. We used regular nuts when reassembling.

Extracting a Broken Commodities from Cylinder Caput

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

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

Drilling tin can be a dangerous and unsuccessful endeavor. The idea is you start drilling in the direct center of the bolt and then step up the drill size in increasingly larger increments until yous're almost at the threads. Then, you tin can apply an extractor to spin the remaining bolt out. We've done this in the past, but it's nervus-racking because if yous pause off a drill flake or hardened extractor inside the head there'southward virtually no getting it out. We contemplated drilling our stud out, but the fact that we have aluminum cylinder heads and this vehicle had a control arm smack in the way of the drill, we opted for the welding route.

Fifty-fifty with a tight 90-caste drill, an upper command arm prevented us from getting a clean bending with the drill extractor on the broken stud.

Your other selection when all else fails is welding a nut onto the end of the cleaved bolt or stud and spinning it out. Not only will the welding give you a secure buy with which to wrench or spin the broken shank out, merely the heat from the welding volition assistance loosen whatever rust, antiseize, or other material that's helping foreclose the broken shank from coming out. If you're working with fe cylinder heads y'all demand to exist extremely careful to avoid actually welding the nut to the cylinder caput or dissentious the threads. For this reason, it's normally best to utilise 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 in that location is you're removing your cylinder heads and taking them to a machine shop to have the stud extracted. However, most modern engines like the 5.7L 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, assuasive you relative safety while attempting to weld on a nut. We used a pair of needle nose pliers to hold a 3/8-inch nut over the hole containing our broken stud. Because the shank was roughly inch downwards in the hole, nosotros used a relatively high wire speed to help make full the gap and let 'er rip. With a nut securely welded to the broken stud, the remaining portion spun right out with no damage.

We fastened our welding basis to the engine and used needle nose pliers to hold a iii/8-inch nut against the head over the hold containing the broken stud shank.

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

Y'all tin can run into the gap between the portion of the cleaved stud and the nut.

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

New Exhaust Gaskets and Studs and Reassembly

Thankfully, afterward a careful inspection we found no cracks in our factory exhaust manifold. Y'all don't want to cheap out and get inferior parts when it's time to reassemble. For our 2004 Hemi we went with a mill Mopar exhaust manifold gasket and a set up of new FelPro studs that nosotros purchased from Height Racing. The FelPro studs came with a blue coating for corrosion resistance and included thread locker on the threads. It seems the gasket blueprint has inverse over time, so after verifying the port sizes on the gasket were the same as the original, we applied some antiseize to the commodities threads and got ready to reinstall the manifold. Ii of the manifold commodities holes are notched to allow the manifold to slide on. This allows y'all to continue the manifold gasket on the head while you dispense the heavy manifold into identify. In our case, we had enough access where this wasn't really an issue, then nosotros assembled both gasket and manifold together, making sure to put studs in the correct holes to take the heat shield. After getting the bolts finger-tight we broke out the torque wrench and over three passes torqued the manifold bolts and studs in the right pattern (we institute ours online) to the correct xviii-lb-ft value for our engine. After the manifold was torqued to the head, nosotros installed some new Grade 8 bolts, lock washers, and nuts and tightened down the downtube collectors to the manifold. Later on a test burn down to verify there were no leaks we buttoned up the inner liner, reinstalled the bicycle, 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-free seal.

A factory Mopar gasket and FelPro hardware kit from Acme Racing were the only parts we needed. K total for this chore came in at $75.39.

The FelPro hardware kit is $30.99 through Summit Racing, merely its high quality with a corrosion-resistant blanket fits perfectly.

We threaded one bolt through the gasket into the head to hold the gasket in identify while we got the manifold ready.

Make certain the bolt pigsty you lot use corresponds with the slotted hole in the manifold and so you lot can just slide it into place.

Nosotros torqued the frazzle bolts to 18 lb-ft per the manufacturer'south pattern, which we establish through an online service manual. If you tin't find yours, just start in the center and alternate crisscross—bottom, top, side, side—until you've done all of them.

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

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

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