Fix It

Replacing the exhaust manifolds on your Ford F-150 truck is a complicated process that varies greatly depending not only on the year of the truck but also the type of engine. The manifolds are connected to the cylinder heads and the catalytic converters. You should talk with your mechanic before attempting this type of repair.

Instructions

V6 Engines

1

Disconnect the trucks negative battery cable, then raise the truck and securely support it on jack stands.

2

Disconnect the electrical connectors to the oxygen sensor.

3

Remove the nuts connecting the exhaust Y-pipe to the manifolds. Apply penetrating oil to the nuts and studs, if necessary.

4

Remove the engine lifting bracket. For the drivers side manifold, remove the dipstick tube from the oil pan by removing its nut and pulling it out. For the passengers side manifold, disconnect the EGR pipe from the manifold.

5

Disconnect the six mounting nuts for the exhaust manifold. Separate the manifold from the cylinder head and remove the old gaskets.

6

Place the replacement exhaust manifold with new gaskets onto the cylinder head. Install the mounting nuts with a torque wrench, tightening the center nuts first, followed by the front pair and the rear pair.

7

Reconnect and install the other components in the reverse order of removal--this can include the engine lifting bracket, oil dipstick tube, EGR pipe and oxygen sensor electrical connector.

8

Lower the truck and reconnect the battery cable.

V8 Engines

9

Disconnect the negative battery cable, raise the truck and support it on jack stands. Remove the inner splash shield from the fender well.

10

Disconnect the EGR pipe at the EGR valve and exhaust manifold if you are removing the drivers side manifold on a 4.6 liter engine. On a 5.4 liter, remove the front and rear heated oxygen sensors and the exhaust support bracket.

11

Remove the starter if youre removing the passengers side manifold. Also remove the stabilizer bar on a 5.4 liter engine.

12

Disconnect the catalytic converter assemblies from the manifold on a 5.4 liter engine by removing their nuts, then move the assemblies to the rear of the truck.

13

Remove the mounting nuts from the exhaust manifold and remove it. Remove the studs from the cylinder heads and discard them and the nuts.

14

Clean the mating surface on the cylinder heads, using a gasket scraper to remove any carbon deposits. Install new studs into the cylinder heads.

15

Place the exhaust manifold over the studs with new gaskets. Install new mounting nuts, working from the rear to the front and alternating between the top and bottom rows.

16

Install the remaining components in the reverse order of removal and lower the truck. If you need to reconnect the EGR pipe, apply a small amount of anti-seize compound on the threads.

A hissing noise coming from the engine of your vehicle combined with liquid spillage from the car can mean trouble for your vehicles exhaust or intake manifold. Such signs can be symptomatic of a manifold leak, which is when your exhaust or intake manifold leaks oil or coolant. If you notice a manifold leak, its important to stop the leak immediately because it can pose a hazard to the passengers in the vehicle.

Repairing the Manifold

If the manifold is leaking due to damage to the exhaust or intake manifold, or the general wear and tear of it, then the most effective way to stop the manifold leak is to repair and replace the manifold. A manifold can be removed from the vehicle and replaced with something new so that the vehicle no longer leaks. If the manifold just has some small cracks in it that are causing the leak, another repair alternative is to have the cracks welded together rather than purchasing and installing a new manifold.

New Gasket

A new gasket that seals the manifold is one way to stop a manifold leak. If a gasket is cracked, it is no longer able to seal and maintain the connection with the manifold, thereby creating a gap between the manifold and the exhaust pipe. Shear stress to the gasket of the manifold is part of the normal wear and tear of the vehicle due to the thermal contraction and expansion that happens each time the engine is turned on and off.

Sealant Solution

You can try to stop a manifold leak by coating the gasket or manifold with a leak sealant. Leak sealants, which are available at auto repair shops, are applied directly onto the affected area of the vehicle and act as a means of sealing the leak so that no more fluid can be lost. This solution is simpler than attempting to replace the manifold or gasket.

Accurate Assessment

A manifold leak can only be stopped if youve isolated the problem accurately. If you misdiagnose the cause for the leak, or think its the exhaust manifold when its really the intake manifold, then you risk prolonging the repair and, meanwhile, the vehicle continues to lose fluids. An accurate assessment is necessary for stopping a manifold leak, so its important to learn how to diagnose and troubleshoot the problems and locate the source of the leak.

The exhaust manifold connects directly to an engines cylinder ports and routes chemical-laden exhaust gases out toward the tailpipe. The seal between exhaust manifold and cylinder ports must be airtight for safety and emission reasons. You may use sealant along with a gasket.

Function

The exhaust manifold plays an important role in engine performance and longevity. Combustion within the engine cylinders creates waste gases expelled through the exhaust system, which begins at the exhaust manifold. You must maintain an airtight seal between cylinder ports and manifold.

Applying Sealant

Every professionally installed exhaust manifold and cylinder head have a gasket compressed between them. Age and engine heat wear gaskets down, reducing the quality of seal between the two components. Though sealant adds seal protection, new gasket installation does not require it.

Safety

A leaking seal or cracked exhaust manifold allows harmful exhaust gases such as carbon monoxide into the vehicle cabin. Carbon monoxide impairs motor functions and in large doses can cause death.

When the exhaust manifold studs break on a Ford F150, the driver will notice a puttering sound on cold start-up because the backside of the exhaust manifold will vibrate, smacking into the engine head. Eventually the oxygen sensors can receive erroneous readings due to an increase in the oxygen passing over the sensor. This could possibly lead to engine performance problems from the change in fuel trim values. In extreme cases your check-engine light might pop on. With the use of pneumatic tools and a long afternoon you can take care of problem.

Instructions

Set Up

1




Determine which manifold is leaking by looking on the backside, closest to the passenger compartment, with a flashlight, for broken studs or visible black soot.

2




Evaluate condition of the nuts and bolts around the manifolds and the exhaust Y pipe, looking for rust. Spray all nuts and studs on the manifolds with a penetrating oil lubricant, such WD40.

3

Gather all of the tools and parts you will need to finalize the project so you dont need to worry about going out to get a tool or part once your Ford F150 is torn apart.

Preparation

4

Jack up the front of the Ford F150 onto jack stands.

5




Remove the wheel on the side where the manifold is leaking, using a socket and ratchet.

6




Remove plastic wheel wells, using ratchets and a pry bar.

Removal

7

Remove the four exhaust nuts that connect the Y pipe to the exhaust manifolds. Depending on the level of rust degradation on the nuts, it might be necessary to use extractor sockets to remove.

8

Remove the exhaust gas recirculation, or EGR, tube if you working on the left side of the manifold. Typically it will be so rusted you will need to cut the tube, using the metal hacksaw, as close to the manifold as possible. Otherwise skip to the next step.

9

Remove the all eight nuts from the exhaust manifold. When removing, dont be surprised if the stud turns and is removed with the nut or breaks off as you turn. Typically, the back nuts are the ones that will break off due to rust and fatigue. Then, remove any remaining exhaust studs that did not come off with the nuts.

10

Remove the exhaust manifold and discard the gasket.

11

Remove any broken studs by attempting to turn with extractor bits and a ratchet. If you are unable to extract, use the 90-degree drill, perably with counter-clockwise drill bits to assist in removal of studs, drilling a hole into the center of the stud, which might release it. Increase drill bit size, as necessary, to remove. Once the layer of rust on the stud is removed from the seat of the hole in the engine head, the stud will freely turn out.

EGR

12

Remove the top portion of the EGR tube from the EGR valve with a wrench, if you are working on the left manifold.

13

Replace the manifold if the EGR tube and nipple are so heavily rusted that you cant remove them.

14

Access the amount of rust and wear on the exhaust manifold. Replace if there is heavy rust build up on the face or clean by using the drill grinder.

Installation

15

Install new EGR tube and nipple if you are working on the left manifold.

16

Position new manifolds in place, over the gaskets, while lightly turning in the studs by hand.

17

Tighten the nuts top to bottom, right to left. In other words: tighten the top right, then the bottom right; tight the second from the right on the top followed by the second on the right bottom, and so on. Always start from the side closest to the back side of the engine.

18

Put the Y pipe back in place and tighten the bolts.

19

Reconnect the EGR valve to the exhaust manifold upper fitting.

In modern automobiles, the exhaust manifold is part of the larger manifold system. Its function is to remove engine exhaust--air and vapor, along with any uncombusted fuels--and inject it into the exhaust pipe to be carried out and away from the engine. A cracked or otherwise faulty exhaust manifold can result in inefficient fuel consumption and a pronounced drop in engine performance. It can allow harmful exhaust fumes to accumulate in the engine compartment, where they can then make their way into the cabin of the vehicle.

Pronounced Exhaust Odors

The most obvious sign of an exhaust system problem is the presence of exhaust odors in the passenger cabin, though this can also indicate a breach of the exhaust pipe beneath the car. To differentiate between the two, run the engine until its warm and open the hood. If there is a distinct smell of exhaust originating from the engine compartment, the problem is very likely in the manifold.

Performance and Noise Issues

Because combustion engines use the natural vacuum pressure caused by the compression, combustion and evacuation of air and fuel, another symptom of a cracked manifold is an obvious drop in engine performance. Weak acceleration accompanied by a stuttering effect may indicate a manifold problem, but it does not necessarily mean the manifold is cracked.

This obvious loss of performance accompanied by louder engine noise points more definitively toward a breach in the exhaust manifold. The noise will typically manifest as a louder exhaust rumble, or a wide-open sound. Again, a breach in the exhaust pipe may also cause this, so be sure to check under the hood while the engine is being accelerated to ensure that the noise is coming from the engine compartment rather than beneath the car.

Identifying Cracks in an Exhaust Manifold

A cracked exhaust manifold is not always immediately apparent. Stress fractures caused by excessive heat can start small and widen over time, making the effect difficult to notice until the engines performance is noticeably diminished.

Because most fractures are caused by heat stress, cracks will form where the heat is most concentrated, in this case where the manifold joins the engine. In older manifolds made of cast iron, cracks are usually harder to see, as rust accumulates rather quickly. In newer engines with aluminum manifolds, cracks may be more readily apparent thanks to aluminums lighter color and resistance to oxidation. Removal of the exhaust manifold and a close physical inspection may be necessary to locate cracks.