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Installing a New Intake Manifold and Gaskets

Disclaimer: We can't accept any responsibility for anything that goes wrong or any missed steps on your job. Use common sense and a good manual if you've never done this before.

This covers removing and reinstalling the intake manifold and exhaust manifold (header) on the 280ZX L28, for example to replace the intake/exhaust gasket. The first few steps are simple and easy to skip, but check everything is disconnected before you start pulling on or unbolting the intake. It'll save you a big headache.

Time: about 2 hours if the job has been done before. If it's your first time, or the bolts have never been out, allow extra time for broken bolts and other repairs.

280ZX L28 intake manifold before disassembly
The intake before disassembly.

Removal

Disconnect Everything

  1. Disconnect the battery ground cable.
  2. Remove the distributor cap, leaving the plug wires attached, to give yourself room to work.
  3. Remove the intake hose between the throttle body and the air flow meter.
  4. Undo the wiring harness clamp and unplug all the wiring on the intake. Be careful not to break any of the brittle clips.
  5. Remove all the vacuum hoses going to the surrounding parts (brake booster, PCV valve and so on).
  6. Drain about a gallon of coolant.
  7. Remove the air bypass valve and its hoses, and the EGR control.
  8. Remove the throttle rod: pull the hairpin clip and the arm slides out.
  9. Remove the pulley from the front of the engine. Loosen the power steering belt first. There's no need to remove the mechanical fan.
  10. Remove the coolant line that runs to the EGR control, above the lower radiator hose.
  11. Disconnect the fuel lines. To relieve the fuel pressure first, touch power and ground to the cold start valve, as described in the factory service manual.
  12. Remove the EGR tube from the intake side. That end is usually not seized like the manifold end.

Unbolt the Manifolds

  1. Disconnect the exhaust at whichever joint is easiest and least likely to break: the header pipe, the manifold flange or the catalytic converter. Soak the nuts with PB Blaster or a similar penetrating oil.
  2. Remove the EGR valve (if equipped), then the heat shield's 12 mm bolts.
  3. Remove the access plate on top of the intake to get to the top exhaust bolt.
  4. Remove the 12 mm nuts on the exhaust manifold under the intake. Leave the 2 nuts at the ends of the exhaust manifold and the 3 in the center; they don't need to come off to remove the intake. Use a wrench, a long extension, a mirror and a flashlight, whatever it takes to reach them.
  5. Using a very long extension with a swivel and a 14 mm socket, remove the 4 intake bolts, then lift off the intake.
  6. Remove the last 5 nuts and remove the header.

Cleaning and Installation

  1. Clean all the gasket surfaces with a scraper. If you use a power disc, don't leave any marks or low spots in the surfaces; they can cause leaks later.
  2. Install in the reverse order of removal. To make the intake easier, first put all the nuts and washers on loosely where the intake and exhaust share studs, so you don't have to reach in there later. Tighten the 5 exhaust nuts that you removed last.
Tip: Use anti-seize (Never-Seez) on the threads when you put everything back together. It makes the job much easier next time. Take your time and have fun.

Related Pages

Sources Used