• 2021

HEMI V8 Exhaust Manifold Bolt Replacement

When the venerable HEMI® V8 engine was re-introduced in 2011, it was an instant hit. Available in 5.7L, 6.2L and 6.4L trim with an optional supercharger and delivering over 700hp in the special Demon package, the HEMI V8 engine has lived up to the legend of its name. With the MDS cylinder deactivating technology, Challengers, Chargers and 300s equipped with this engine are fast on the street, but achieve very respectable mileage on the highway.

EXHAUST MANIFOLDS ON THE HEMI® V8 ENGINE

The HEMI® V8 exhaust manifolds for the 6.4L design are a tube-in-shell air gap design to maximize durability and performance. These manifolds are made of stainless steel stamped shells and stainless steel tubes with a powdered metal outlet. A layered graphite over perforated steel manifold gasket is used to provide sealing to the cylinder head. The 5.7L version exhaust manifolds are made of high silicon, molybdenum cast iron. A multi-layer stainless steel gasket is used to improve sealing to the cylinder head.

The exhaust manifolds collect the engine exhaust gases exiting the combustion chambers, then channel those gases to the exhaust pipes/catalytic converters. A combination of bolts and studs secure the exhaust manifolds to the two cylinder heads.

Whenever the exhaust manifolds are removed, the manifolds should be inspected for cracks. Inspect the mating surfaces for flatness with a straight edge. Gasket surfaces must be flat within 0.008 inch per foot.

The exhaust manifolds should be aligned properly when installed. To align the exhaust manifolds correctly, loosen the clamps and support brackets, then align the exhaust system starting at the front, working rearward. Tighten all clamps and brackets once the alignment and clearances are achieved. Don’t forget to properly torque the exhaust manifold bolts and studs.

BROKEN BOLTS AND STUDS

There have been isolated reports of one or more of the exhaust manifold retaining bolts and/ or studs breaking on the 5.7L HEMI® V8. This is a condition that has only been seen on the 5.7 HEMI V8, not on the 6.2L or 6.4L. What the driver will hear is a noise that sounds very much like the clicking of a dirty hydraulic valve lifter. But it is not that sound. It is the sound of exhaust gas leaking from the exhaust manifold/cylinder head mating surface. This noise will increase as more bolts/studs break. The solution is replacement of the broken bolts/studs.

Figure 1 is an illustration that shows both exhaust manifolds, manifold gaskets and heat shields. Listed below are the part numbers and reference numbers:

FIGURE 1 | MANIFOLDS/GASKETS/HEAT SHIELDS

FIGURE 1 | MANIFOLDS/GASKETS/H AT SHIELDS

  1. Exhaust manifold gasket: 05045495AA, 2 required
  2. Exhaust manifold: 05045486AA (Right);68045559AB (Left)
  3. Bolt, exhaust manifold-to-cylinder head:06510140AA, 9 required
  4. Stud, exhaust manifold-to-cylinder head:06510141AA, 4 required
  5. Nut, heat shield-to-exhaust manifold:06505316AA, 7 required
  6. Exhaust manifold shield: 53032968AD, 2 required
  7. Nut: 06036684AA, 4 required
  8. 8. Bolt: 06036734AA, 4 required
  9. Stud, exhaust manifold-to-cylinder head:06509863AA, 4 required

Figures 2 and 3 are illustrations of the six individual pieces (bolts / studs / nuts).

FIGURE 2 | BOLTS & STUDS FIGURE 3 | NUTS

REPLACING BROKEN BOLTS AND STUDS

Before replacing the exhaust manifold bolts/studs, it must be determined that one or more is broken. A visual inspection of each bolt or stud should indicate which one(s) is broken. Also, you can insert a deep well socket on each bolt/stud and turn it by hand. If it’s broken, the end should come off easily in the socket.

Now that it has been determined that one or more bolts/studs are broken, the broken pieces must be replaced. Let’s see how that is done. The exhaust manifold must be removed.

Note: Depending on the vehicle you are working on, removing the inner wheel liner may improve access the exhaust manifold bolts.

Next, disconnect the oxygen sensor wire harness connectors. Saturate the catalytic converter-to-exhaust manifold retaining bolts and nuts with Mopar® Rust Penetrant, or equivalent. Allow five minutes for the penetrant to work. Disconnect the catalytic converter from the exhaust manifold.

Remove the heat shields. Using the sequence shown in Figure 4, remove the left side exhaust manifold retaining bolts.

FIGURE 4 | LEFT SIDE REMOVAL/TIGHTENING SEQUENCE

FIGURE 4 | LEFT SIDE REMOVAL/TIGHTENING SEQUENCE

The sequence for the right side exhaust manifold is shown in Figure 5. Remove the exhaust manifold and gasket.

FIGURE 5 | RIGHT SIDE REMOVAL/TIGHTENING SEQUENCE

FIGURE 5 | RIGHT SIDE REMOVAL/TIGHTENING SEQUENCE

After the exhaust manifold and gasket have been removed, you will see the remnants of one or more broken bolts. If there is enough of the bolt protruding from the cylinder head, you might be able to grab it with a pair of Visegrips® and remove it. If there is not enough of the bolt to grab, place a nut over the remnant of the bolt and weld the inside of the nut to the bolt. Using the appropriate socket, remove the broken bolt.

After all the broken bolts have been removed, clean the gasket surface. Position the new exhaust manifold gasket in place, align the gasket and the exhaust manifold with the bolt holes on the cylinder head and install the two upper retaining bolts finger tight.

Note: Refer to Figure 1 for the correct bolt and stud numbers; also, P/N 06509863AA has a white paint dot on the end of the stud; P/N 06510141AA, which looks the same, does not have the white paint dot.

Install the remaining exhaust manifold retaining bolts. Tighten to 18 ft-lbs. Refer to Figure 4 (left side) and Figure 5 (right side) for the correct tightening sequence. Install the heat shields, then reconnect the catalytic converter to the exhaust manifold. Reconnect the oxygen sensor wire harness connectors. Re-install the inner wheel well liner and lower the vehicle to finish the job.

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