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I have to replace the exhaust manifold on a 1988 f150 4x4 with a 4.9 engine how hard is it on on this truck
 

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It's a hell of a lot easier than pulling the motor.Is it cracked or have the studs snapped.If the studs snapped,SnapOn has a nice extraction set that allows you to place a sleeve into the hole where the studs broke and the drill slides right down the center of sleeve.Now you have a perfect sized hole to install the stud extractor and your home free.
 

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Not sure how they are on this particular engine, but have you ever changed them out on any vehicle? I did some on a 6.5 turbo diesel recently and have some tips if you would like.
 

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REMOVAL & INSTALLATION

1987-93 4.9L Engine

  1. Disconnect the negative battery cable.
  2. Remove the air inlet hose at the crankcase filter cap.
  3. Remove the throttle body inlet hoses.
  4. Disconnect the accelerator cable at the throttle body.
  5. Remove the cable retracting spring.
  6. Remove the cable bracket from the upper intake manifold.
  7. Disconnect the fuel inlet line at the fuel rail. Don't kink the line!
  8. Remove the upper intake and throttle body as an assembly (see ).
  9. Tag and disconnect all vacuum lines attached to the parts in question.
  10. Disconnect the inlet pipe from the exhaust manifold.
  11. Disconnect the power brake vacuum line, if so equipped.
  12. Remove the bolts and nuts attaching the manifolds to the cylinder head. Lift the manifold assemblies from the engine. Remove and discard the gaskets.
  13. To separate the manifold, remove the nuts joining the intake and exhaust manifolds.
To install:

  1. Clean the mating surfaces of the cylinder head and the manifolds.
  2. If the intake and exhaust manifolds have been separated, coat the mating surfaces lightly with graphite grease and place the exhaust manifold over the studs on the intake manifold. Install the lockwashers and nuts. Tighten them finger tight.
  3. Install a new intake manifold gasket.
  4. Coat the mating surfaces lightly with graphite grease. Place the manifold assemblies in position against the cylinder head. Make sure that the gaskets have not become dislodged. Install the attaching nuts and bolts in the proper sequence to 26 ft. lbs. If the intake and exhaust manifolds were separated, tighten the nuts joining them.
  5. Position a new gasket on the muffler inlet pipe and connect the inlet pipe to the exhaust manifold.
  6. Connect the crankcase vent hose to the intake manifold inlet tube and position the hose clamp.
  7. Connect the power brake vacuum line, if so equipped.
  8. Connect the inlet pipe at the exhaust manifold.
  9. Connect all vacuum lines.
  10. Install the upper intake and throttle body as an assembly.
  11. Connect the fuel inlet line at the fuel rail.
  12. Install the accelerator cable bracket at the upper intake manifold.
  13. Install the cable retracting spring.
  14. Connect the accelerator cable at the throttle body.
  15. Install the throttle body inlet hoses.
  16. Install the air inlet hose at the crankcase filter cap.
4.9L EFI engine intake and exhaust manifold bolt torque sequence
 

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Hopefully you've soaked the crap out of all the exhaust manifold bolts with some PB Blaster (or similar penetrating oil).

Before putting everything together, put the gasket up to the head and see if ALL of the ports line up correctly. Often times the gasket must be cut and each piece will need to be done individually. I used a little hi-temp RTV gasket maker to help hold the gasket in place while I fitted the manifold up. Also, try using the copper spray gasket maker on both sides of the gasket. It really seals up nicely so you won't get any exhaust leaks. And be sure to cover the exhaust ports up when you're spraying the heads.

Another thing, use some anti-seize on the exhaust bolts when reinstalling them.

Once you get it all back together and you fire the engine up, spray some soapy water over all of your exhaust piping and look for exhaust leaks, mostly around that new gasket you put in.
 

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The 4.9L exhaust manifold comes off with the intake attached to it. Usually removing it is not the problem. It's getting it to line back up and seal when you re-install it. Most of the ones that I did, the exhaust manifold warped a little and it made it almost impossible to get a good seal at the head. Some even have to be machined to make them fit. Just need some patience.
 
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