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Tuesday, October 21, 2014
 

Ford, Lincoln, and Mercury. 4.6L Intake Manifold Replacement.

 

How to replace the intake manifold on Fords, Grand Marquis, and Lincolns. Save money by doing it yourself.

Caution:

  • Do not attempt this job unless you're confident you can do it.
  • Take full responsibility if you make costly mistakes.
  • Causing further damage to your car is a possibility.

Ford Intake Manifold Replacement.

It is quite common for intake manifolds to crack on Fords, Grand Marquis, and Lincolns equipped with a 4.6L engine. This is a very expensive job, however if you have some mechanical ability, you may be able to do it yourself. Not only will you save money on labor but you'll also save a lot of money on the manifold if you shop around online and aren't in a rush to put the car back into service.

Typically these manifolds burst in the front by the alternator. New intake manifolds correct the original design flaw and come with an aluminum crossover to prevent this from happening again. On my car, a 1999 Grand Marquis, the manifold was cracked in the back by at the heater hose.

How To Replace The Intake Manifold on Ford Products.

The intake manifolds are fairly easy to replace if you're mechanically inclined and have some experience working on cars. Older Fords, Lincolns, and Grand Marquis had distributors and spark plug wires. Newer models came with a coil on plug (COP) setup. You'll need basic tools any backyard mechanic would have plus a torque wrench.

On my car I replaced the intake manifold, spark plugs, and all the cooling system hoses. The new manifold, manufactured by Dorman Products was high quality and less than $200 online. The cooling system hoses cost about $225. and the factory recommended plugs were $25. The entire job took seven hours and I haven't worked on cars for many years. An experience mechanic could have done everything in five hours. I estimate that I saved $1100. total

Once you get started, it will be obvious what you need to take off the engine to get to the manifold. Step by step directions are available online but your car might be built differently. Use common sense and your mechanical experience to avoid causing further damage to your engine. The heads are made of aluminum and can be damaged very easily if you don't know what you're doing. Also there is a risk of parts, tools, and dirt fall into the engine if you're not careful. Also you will be working with the fuel system. Fire is always a possibility.

I've never worked on fuel injected cars before so I was very nervous, especially since those cheap looking plastic injectors cost a $100 each! But to my surprise there was no problem at all. The bottom O Rings on each injector were dirty so I cleaned them with WD 40. They were still soft and undamaged so it was not necessary to replace them.

Tips On How To Replace Ford Intake Manifolds.

  • Take the pressure off the fuel system by removing the fuel pump relay and cranking the engine for 20 seconds.
  • Disconnect the battery.
  • If you have an air compressor use it to clean up the engine before you start.
  • If you have a digital camera, take pictures as you take parts off the engine.
  • I took the entire throttle body off and moved it to one side with the cables attached
  • On my car there was a large bracket on the back left side of the engine that blocked access to injector rails and manifold.
  • To remove this bracket there's a bolt on top and one in the back of the engine. In my opinion removing this bracket was the hardest part of the job.
  • I left the fuel lines and injectors attached to the injector rails and lifted the entire assembly out of the way.
  • Fuel is highly flammable. Take safety precautions to avoid fire.
  • It was necessary to remove the alternator but this was very easy to do.
  • The manifold bolts screw into aluminum heads so I sprayed WD 40 on each bolt and used a torque wrench to remove them.
  • I removed the COP's (Coil on plugs)
  • Once the intake manifold was off, removing the gaskets and cleaning the heads was fairly easy. Avoid getting lint and debris into the engine ports.
  • The new intake manifold from Dorman was not flat! I called the company and they told me they are designed that way. When you torque down the manifold it will sit flush with the heads and not leak.
  • It's a good idea clean out the bores that the spark plugs fit into. On my car, some holes were filled with antifreeze.
  • I carefully torqued down the new manifold a little at a time using the instructions that came with the manifold.
  • Reinstalling the injector assembly was much easier than I thought it would be. Thanks to WD 40 the injectors slipped into the manifold with ease.
  • Next I filled the engine with coolant through the thermostat housing and I put coolant into the reservoir. This is important.
  • I reinstalled all the other parts and connected everything up.

I expected the car to run rough when I started it, but it was as smooth as silk. It started in a couple of seconds and ran just like always did. There were no leaks. It's important to watch the temperature gauge as the engine warms up. Make sure the thermostat is opening and closing correctly. You will probably need to add a little more coolant to the reservoir.

 


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