1998 Lincoln Town Car 4.6L Intake Manifold Replacement

This 4.6L Intake Manifold Replacement Kit 615-178 Fits Ford 4.6L (8th Vin Digit W, X, 6, 9 By Application) Which runs from 1996 to 2000

This guide is for the Ford 4.6L Intake Manifold Replacement procedure. Ford made themselves a problem at the turn of the millennia with the 4.6 and 5.4 Triton motors. They were best known for blowing out the spark plugs, especially if you after a tune up. The other main issue was that the plastic Intake Manifolds would crack at the water channels and pour coolant out of them. 

This "How To' page will guide you through how to replace the intake manifold on a 1998 Lincoln Town Car with a 4.6L. However this can apply to other makes, models and years. You will be provided step by step instructions, video, specifications and a tool and supply list that should cover everything you need to complete this job. This focuses on using the 4.6L Intake Manifold Replacement Kit, however, the procedure is the same without the kit.

Vehicle Application

How To Instructions

Step 1 - Relieve the fuel pressure:

Pull the fuel pump fuse to disable the fuel pump from running. Start the car and let it run till it quits. The fuel pressure has now been released.

Step 2 - Disconnect Battery:

Loosen battery clamp on the negative terminal, then remove battery clamp and place it out of the way so it doesn't reconnect to the battery.

Step 3 - Drain Engine Coolant:

The drain plug can be located on the left side (Driver's Side) underneath at the bottom of the radiator. Some drain petcocks point toward the rear and some point straight down. Turn counterclockwise to drain coolant. Drain it into a pan to avoid contaminating the environment.

Step 4 - Remove Serpentine Belt:

Make note how the belt is routed, make a drawing or take a picture if you do not feel you can remember. Insert a 3/8 inch pull bar or ratchet into the tensioner and turn it clockwise to release the belt. Remove belt by hand from all the pulleys.

Step 5 - Remove Alternator and Bracket:

Pull up the power lead connector cover, using a 10mm wrench or socket, remove the power lead nut and wire from the back of the alternator. Unplug the regulator wires from the alternator. Remove the four 10mm bolts from the bracket and alternator, remove bracket. Loosen and back the two lower 10mm bolts out a little and lift the alternator upward to remove. The two bottom holes on the alternator are slotted so you can rest the alternator on them for easy installation.

Step 6 - Remove Engine Cover and Air Breather Tube:

There are a variety of engine cover designs, so you may have one to two 8mm or 10mm nuts to remove or a single bolt that uses the end of a 1/4 inch ratchet drive. Lift cover and or slide it forward and up to remove. Unplug the MAF Sensor connector from the sender on the air tube near the breather element box.

Release the two clips on the breather box. Push down and pull towards the engine then pull up. Disconnect the two smaller breather hoses and then loosen the breather tube clamp on the throttle body. Pull the breather tube off.

Step 7 - Remove The Throttle Body Assembly:

Remove the two 10mm bolts from the Throttle Cable Retainer Bracket, slide the cables out. Pull the throttle cable toward the front creating slack in the cable then unsnap and slide off pin. Then pull the cruise control cable enough to get the open position of the end slide to where it will come off pin. Remove the throttle lever spring.

Remove the coolant line, if applies and vacuum lines front he throttle body. Disconnect the large breather hose, the vacuum ports on the front of the valve body. Remove the two 8mm bolts from the EGR valve and leave hanging there, just ensure that the EGR valve is no longer bolted to the Throttle Body. Unplug the connectors from the Throttle Position Sensor and from the Air Idle Control Valve. Now remove all four 8mm bolts from the Throttle Body and remove Throttle Body.

Step 8 - Remove The Fuel Lines:

Remove the two fuel lines from the fuel rails. First remove the safety clip that is snapped over the fuel lines to fuel rail. You will need a quick release tool to pull the fuel lines from the rail. Refer to the video (5:45) for a better description. There should not be any pressure on the lines if you pulled the fuse and started the car to relieve the fuel pressure from Step 1. 

Step 9 - Disconnect Fuel Injector, IGN Coil Pack Connectors and Remove IGN Coil Packs:

All of the connectors on both the Fuel Injectors and Coil Packs are a squeeze type release. Squeeze each connector and pull at the same time. Once all the Coil Packs are disconnected, remove the one 10mm bolt per Coil Pack and pull upward to remove Coil Pack.

You may have to twist the Ignition Coils as you pull upward to get them to release from the spark plug. Some Coil Packs can stay with the intake if too hard to pull from the fuel rail sitting on top of them. You can pull the fuel rail before pulling the Coil Packs, it is a matter of preference.

Step 10 - Remove Cowl Vent Wiper Unit - (Town Cars)

There is a heavy metal bracket that bolts from the back of the engine and curves over top the intake manifold. The best way to get your hands on these two bolts to remove it is to remove the Cowl Vent Wiper Unit.

You will notice that it hangs a good ways over top the manifold thus hindering removing the manifold. This also allows you to get to the back bolts on the manifold and makes R&R of the manifold much easier. Refer to the Video (16:47) to get a better description of R&R of this tray.

Step 11 - Remove Intake Manifold

Loosen and slide back upper radiator hose clamp where hose connects to thermostat housing. Pull hose from thermostat housing and peel hose back out of the way. Loosen heater hose clamp on hose on the back passenger side and pull hose off. Remove all nine 10mm bolts from the intake manifold. There should be four bolts on the driver's side and five on the passenger side. The manifold should lift straight off as there are no gaskets that will bond it to the heads.

This design manifold uses o-rings, however they can get stuck. You may have to use a small pry bar or screwdriver to break the manifold loose but no real brute force should be necessary. If you are finding a strong resistance to lifting off, check for any bolts or brackets you may have missed.

Step 12 - Engine Cleanup And Prep For New Manifold

Luckily there are no gaskets to scrape off. However you do want to make sure that the surface where the manifold bolts to is clean of all debris. This will ensure the o-rings will seat properly against the heads. If you have access to an air die grinder, using a mushroom cup with a medium grit scuff pad, run this over the surface the manifold bolts to.

You will want to put paper towels or rags in the intake and water port holes before cleaning. This will help avoid getting any debris or contaminates in these ports. You can also use hand sandpaper, about 220 grit over the surface. Once you have the metal clean, using air, blow all the debris off and also blow the spark plugs holes out as well. Debris can cause a short to ground or keep the coil pack from seating on the plug properly.

I recommend replacing the spark plugs if they have never been changed. This would be the easiest time to change them. I would also replace the Coil Packs as well for the same reason. When replacing the spark plugs, blow the hole out before unscrewing them so no debris will go down into the cylinder. I highly recommend applying anti-seize on the spark plug threads so that for the next tune up, they will come out with ease.

Step 13 - Swap Over Fuel Rail From Old Manifold To The New

Remove the four 10mm nuts, two on each rail. Be careful pulling the rail up as the injectors usually tend to stay stuck to the rail as they come out of the ports on the manifold. If you use a screwdriver to pry with, be extremely careful as you can break or crack the injector or damage the rail.

Once the injectors and rails are off, remove the old o-rings from the injectors and clean the grooves. You will want to purchase a Fuel Injector O-Ring Kit. There should be an O-Ring for the top and bottom of the Injector, 16 total. I use Automatic Transmission Assembly Lube on the O-Rings. It reduces the chances of damaging the o-rings and makes the assembly much easier.

With the new o-rings installed and lubed, press the injectors into the rails. Align the injectors into each port on the new manifold and press on the rails pushing the injectors into the new manifold. You may want to leave the four nuts off the rails to possibly aid you in getting the new coil packs in. You may have to have some flexibility on the rails to allow clearance to press the coil packs onto the spark plugs.  

Step 14 - Swap Over Thermostat Housing And Replace Thermostat

Remove thermostat housing from old manifold by unscrewing and removing the two 8mm bolts. Some thermostat housings are a tapered fit to seal, meaning you don't have to use a gasket or seal that comes in the kit. If you have a leak around the housing, then use the gasket. However,If you find an old gasket or o-ring seal on the old manifold, then use the exact match from the kit.

If going without the gasket, it doesn't hurt to apply a thin film of gasket maker on the tapered edge and on the machined flat surface. You will want to clean the housing before installing it and I HIGHLY recommend installing the new thermostat that comes in the kit. Lay the thermostat in the hole, spring side down where it will set flush in the recessed groove. Tighten the two bolts to 18ft-lbs.

Step 15 - Install The New Intake Manifold

With all the surfaces clean, set the new intake manifold down onto the engine. Install the nine 10mm bolts and tighten them following the tightening sequence in the Information Section below to 18ft-lbs.

Go ahead and put the rear heater hose onto the back of the manifold. Intake may come with a cap over the nipple, if so remove. Inspect heater hose to see if it needs replaced with new. Inspect clamp as well to ensure that it is clamping smoothly and still staying round.

Step 16 - Reassemble Coil Packs, Fuel Rails And Lines

Install all eight ignition coil packs. Apply some dielectric grease to the inside of the boot and onto the metal connector. Spray a light coat of silicone oil on the outer side of the boot, this will help the coil pack to slide on easier plus help future removal from being stuck onto the plug.

Put all four 10mm, (could be 8mm on some engines), nuts back on the fuel rails and tighten to approximately 10ft-lbs. Connect fuel lines by pushing them firmly until the click back on to the tubes from the rails. Reinstall the safety clip that laps over the fuel line and rail tubes.

Make sure no positive wires to the alternator are touching ground. Ensure the fuse to the fuel pump has been reinserted. Temporarily reconnect the ground cable back onto the battery and turn the key on. You are checking to see if you have any fuel leaks anywhere on the fuel rail, injectors and the fuel lines.  

Step 17 - Reassemble Throttle Body

Ensure that the bottom of the Throttle Body is clean as it will seal against the o-ring already made into the intake manifold. Set the Throttle Body onto the manifold and install the four 8mm bolts and tighten to 15ft-lbs. Tighten the two 8mm EGR to Throttle Body bolts to 15ft-lbs.

Reconnect all hoses and electrical connectors. Connect the throttle cable and cruise control cable before installing the cable mounting bracket back to the throttle body. Reinstall the throttle spring.

Step 18 - Swap Over Any Sensors

This particular Town Car did not have any sensors in the manifold but that isn't to say that what you are working on doesn't. The only sensors would be the CTS (Coolant Temperature Sensor). The other would be the Temperature Gauge Sensor for the gauge or idiot light for the dashboard. You will find both or one of these on the front of the manifold in the aluminum section where the thermostat housing is.

I recommend replacing sensors with new ones. However if you use the old ones, clean the threads properly and apply a thread sealant before installing them. Do not over tighten them .

Step 19 - Reinstall Back Bracket

Reinstall the large back bracket that bolts to the back of the engine and hangs over the manifold. There are two bolts that could be 13mm to 14mm heads. These are hard to see so it will be a feel and find. 

Step 20 - Reinstall Alternator

Set the alternator onto the two studs pointing out from the front of the engine. Before mounting the upper bracket or tightening any bolts, reconnect all wires and connectors to the alternator. Set the upper bracket on and install the four 10mm bolts. Note: Some models used studs instead of bolts, if this is the case, you will need to transfer the studs from the old manifold to the new. Fully tighten the two bottom bolts and then the top four bolts. 

Step 20 - Serpentine Belt - Upper Radiator Hose

I would recommend replacing the serpentine belt if it hasn't been changed in a while or if you have no idea how long it has been in use. It might be a good idea to change the Serpentine Belt Tensioner if your engine has over 125000 miles. Signs of a weak tensioner are squeaks and squeals when first starting the engine or when you first turn on the A/C. You should refer to any diagram that is either on the vehicle or from any notes you made of the belt path.

The path should go as follows: 

Loop Belt around crank pulley > take it around water pump pulley > bring it over the belt tensioner > take it under the A/C pulley > bring it over the idler pulley > take it around the power steering pulley. Pull all the slack up toward the alternator pulley. Using a 3/8 inch pull bar or long ratchet, turn the tensioner clockwise and slip the belt over the alternator pulley.

Once the serpentine belt is on, push the upper radiator hose back onto the thermostat housing. Inspect hose and clamp to ensure they do not need to be replaced.

Step 21 - Reinstall The Air Intake Tube - Engine Cover

Slide the Air Intake Tube back onto the throttle body and tighten clamp. Reconnect the MAF (Mass Air Flow) Sensor wire connector. Snap the top of the breather box back down the the air filter box. Reconnect the two breather hoses if applies. Reinstall Engine cover.

Step 22 - Fluids - Battery - Start

This system is a closed radiator system meaning you can't pour coolant straight into the radiator. You will have to fill the reservoir with coolant and let drain into the system. You will have to do this a few times until it seems the coolant will not go into the system anymore.

Before starting the car, you may want to change the oil. Depending on what type of leak you manifold had, there is always a possibility that the engine may have sucked some coolant in through the intake ports. I recommend changing the oil, if your sure that no coolant got into the engine, you should be ready to start the car.  

Reconnect the battery cable and proceed to start the car. Turn the ignition key to the on position and let the fuel pump charge the lines before cranking the engine over. It should prime within 15 seconds. Start the engine and look for leaks. You will need to watch the coolant reservoir as the coolant will continue to go down and into the system.

Keep filling it until it seems it need no more. The thermostat will have to open for the engine to fully fill up with coolant. This can take some time for it to get hot enough to fully fill the engine. You may have to put the cap on the reservoir and take the car for a short down the street and back run. Repeat a few times and then check the coolant level again.

Constantly check for leaks around the front and rear of the manifold and where the manifold bolts to the heads. I recommend re-torquing the eight intake manifold bolts once the engine has got to full operating temperature.

Step 23 - Reinstall Cowl Vent Wiper Unit - Final Step

Once you are certain there are no leaks, you can now reinstall the cowl wiper unit. Refer to the Video (16:47) for bolt locations. Once bolted back in, ensure that the electrical connector is reconnected. Run wipers to test operation.

I recommend driving the car for about four or five miles, keeping close to home for testing. Then park the car and let it fully cool down then recheck coolant level as this system is not the easiest to fill up the first time out. You may want to check it over the next few days as close systems like this one has to burp the air out.

Information

Bolt Torque Specifications:

Click the button below for a complete engine torque specification chart...

Intake Manifold Bolt Torque Sequence...

Common Issues With Original Manifold...

How To Video

Watch My YouTube How To Video

This video goes over how to change out a 4.6L intake manifold on a 1998 Lincoln Town Car. Even though your car may be around this year, always check your local dealer with your VIN number to make sure the intake isn't still active under the recall they made on this particular manifold problem.

Manifold, Tools & Supplies

Browse RodsShop Amazon Store-Front for all parts and materials needed for this 4.6L Intake Manifold Replacement job. All parts and materials on this store-front have been hand selected based on preforming this repair multiple times. So, everything other than the basic tools will be listed. Some parts are only if needed, it will be up to the mechanic to decide if other parts needed replaced. RodsShop is an Amazon Affiliate