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Jeep Wrangler JK: The Ultimate Exhaust Manifold Guide

Leaky exhausts sound bad. If your Wrangler sounds embarrassing, a cracked exhaust manifold is likely the problem.

By Mark Garrett - November 25, 2015

This article applies to the Jeep Wrangler JK (2007-Present).

You take your Wrangler a lot of places. If you go off-road, water can splash on hot exhaust manifolds and crack them. If they crack, the exhaust leak will sound horrible—like an old tractor. Sometimes the manifold just cracks after getting some age on it. Fortunately, you have a multitude of choices when it comes to replacement manifolds. Stock cast iron manifolds can be purchased from many companies and if you want to upgrade, you can choose fabricated stainless steel manifolds. Changing exhaust manifolds is not really any fun, but as long as you have patience, you can do it.

Table of Contents

How to Replace Exhaust Manifold

Materials Needed

  • Light
  • 3/8" drive ratchet set
  • long extensions and U-joint
  • 10mm and 15mm sockets
  • Penetrating fluid
  • Anti-seize compound
  • Manifold
  • Torque wrench
  • Jack and stands (optional)

Before we get too far, keep in mind that bolts related to the exhaust system are often locked up. Since the manifold bolts go into the aluminum heads, if a bolt twists off or ruins the threads, you will be very, very unhappy. Use extreme care removing these. It may be necessary to use an acetylene torch to break bolts free.

Step 1 – Locate the exhaust manifolds

Lift the hood and locate the exhaust manifolds down to the sides of the engine below the valve covers. A heat shield covers them and the spark plugs are cradled by them.

Figure 1. The manifolds are deep down in an unfriendly place.

Step 2 – Remove exhaust pipe

Your Wrangler sets pretty high, but you may still need to jack it up to get the access you need to the exhaust bolts. Use standard precautions when jacking it up.

Figure 2. Exhaust bolt.

The exhaust pipes are held on by two bolts that screw into nuts with keepers to make removing them a little easier.

Figure 3. Exhaust pipe nuts and keepers.

Soak the nut keepers in penetrating fluid and allow to set; the longer, the better. Using a long extension, U-joint and 15mm socket, remove the bolts from way up in there. If the nuts twist, you will have to use locking pliers to hold them. If yours look like the ones in Figure 3, you will be happy, but If it looks like Figure 4, not so much (plus the manifold is cracked).

Figure 4. Rusty exhaust nuts and keepers.

Step 3 – Remove heat shields and manifold

The heat shields are made of thin sheet metal. The top is held on by two of the manifold bolts. Remove them with a 10mm socket and extension. The lower one is held on with a single nuts that is also 10mm.

  • Figure 5. Heat shield and manifold bolts visible.
  • Figure 6. Exhaust manifold heat shields.
  • Figure 7. Exhaust manifold showing lower heat shield stud (arrow).

Remove the remaining four bolts and lift the manifold and gasket off. Clean the head where the manifold bolts on. Also, be sure the exhaust pipe flange is smooth for a good seal.

Figure 8. Engine without manifold.

Step 4 – Replace the manifold

Install the nut clips on the manifold with anti-seize on the nut threads. Put the new manifold and gasket in place on the head. Put anti-seize compound on all of the bolt threads. Start the four bolts that do not hold on the heat shield and tighten finger-tight. Starting from the middle and going out, torque the four bolts to 22 ft/lbs. Start the exhaust bolts in the nut keepers and snug up the two evenly. Torque the bolts to 30 ft/lbs. Install the upper heat shield and torque the bolts to 22 ft/lbs, then the lower one and tighten the nut snugly. That does it for replacing a stock manifold.

Figure 9. New exhaust manifold.

Exhaust Manifold Review

Your choices for manifolds are plenty. It is easier to just replace the iron manifold with another one, but more than likely it will crack again. Stainless steel replacements are now offered that look like a header, but fit just like a stock. They will last a long time, but are more expensive. There may be a slight performance gain with these 'shorty' replacement, but not much.
Dorman
Crown
Rugged Ridge
Gibson
Price
 $70 $70 $325 $615
Finish

Raw

Raw

Raw

Ceramic
Material
 Cast steel Cast steel Stainless steel Stainless steel
Length
 Stock Stock Shorty, stock Shorty, stock
Warranty
 Limited Lifetime Limited Lifetime Limited Lifetime Limited Lifetime
Best Quality: Gibson

Best Value: Dorman

Dorman

Price – $70

Material – Cast steel

Length – Stock

CARB Approved – Yes

Warranty – Limited Lifetime

A good OEM replacement. Fits like the original, which is good, but it will also crack like the original. Includes gasket and heat shield. Cast iron construction, which is the same as the original. Leak-resistant for long lasting performance. Dorman is an old supplier, so they know how to make parts. Recommended for anyone looking for a standard OEM replacement and needs the heat shields.

Shop around for the best price.

Crown

Price – $70

Material – Cast steel

Length – Stock

CARB Approved – Yes

Warranty – Limited Lifetime

Another good OEM replacement with all of the advantages and disadvantages. No heat shields or gaskets included. Crown Automotive is a manufacturer and distributor of quality replacement parts for Jeeps. Recommended for anyone looking for a standard OEM replacement without the heat shields.

Shop around for the best price.

Rugged Ridge

Price – $325

Material – Stainless steel, fabricated

Length – Stock

CARB Approved – Check with seller

Warranty – Limited Lifetime

These are what are commonly called 'shorty headers' that are designed to fit in the place of the OEM cast manifolds. There may be weight savings, but don't look for a lot of increased performance. They should not have the cracking issues that the stock manifolds have. Rugged Ridge exhaust headers are constructed of 409 stainless steel to ensure a long life. Each complete kit includes manifolds, gaskets, hardware, clamps and instruction sheets. Recommended for those who want an improvement over OEM, but still fit with the stock exhaust.

Stainless steel will not rust.

Gibson

Price – $615

Material – Stainless steel, fabricated

Length – Stock

CARB Approved – Yes

Warranty – Limited Lifetime

These OEM replacements are fabricated of stainless steel and have a ceramic coating, which keeps the heat inside them. They will never rust and should last a long, long time. Every Gibson header is Dyno-tuned and engineered to deliver more usable horsepower and torque at low as well as mid-range RPM. Designed as a direct replacement for the factory manifolds, using the stock crossover pipe will not affect the factory warranty. Recommended for those who want an improvement over OEM, but still fit with the stock exhaust.

Ceramic coated stainless steel will not rust.

Pro Tip

The choice of manifolds or headers is yours. The OEM style cast manifolds are a direct fit, bolt-on. They have the same limitations though. The stainless fabricated ones will never rust and shouldn't every crack. They may flow a little better, but not that you can feel. Be very careful removing the bolts that hold the manifold to the head. If one breaks, it is ugly and WILL ruin your day. I always use anti-seize on these bolts.

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