According to the JTIS manual..All the intake manifold Bolts are tighened to 10 Nm or 88.5inch poundsor 7.375 foot pounds...I'd use some gasket sealer with the new gaskets and tighten to 90 inch pounds and call it a day.

 

I just did my upper/lower manifold gaskets and spark plugs about two month ago. Fortunately it's not that big of a job, but the all of the necessary gaskets run about $150. Do NOT use any sealer on them. They are meant to go on dry.
You will want to replace the upper manifold gaskets (6) lower manifold/fuel injection manifold gaskets (6), and the throttle body gasket. And while you have the upper intake manifold off of the car, it's a good idea to replace the two intake manifold tuning valve gaskets as they tend to go bad fairly often. Not to mention it's much easier to remove the lower valve if the manifold is off of the car.

 

How many miles are on the car in question? Of course they can be reused, up to a point. If the car has enough miles on it to justify a spark plug change it's probably time to replace the gaskets.

 

In the JTIS manual it states to drain the coolant. Is that necessary? Are there coolant passages in the upper plenum? I do believe the manual but am just curious from someone who has been there.

 

keith - Draining the coolant is not necessary. You will have to remove two or three vacuum lines from the manifold, remove the 4 bolts holding the throttle body to the upper intake (the tb will stay in the car, and kind of just float there), loosen a couple of screws on the rear of the manifold in order to seperate it from the wiring harness that runs behind it, remove a small support bracket on the rear of the manifold and one on the left hand side under the throttle body. After that, remove the (6?) bolts (I can't remember how many) that hold the upper intake manifold down, then you can get to the lower fuel injection manifold. Remove the black plastic cap that covers the schraeder valve on the fuel rail. Covering it with a rag, press the valve to release the fuel pressure in the system. Not much fuel will come out, but enough to justiy covering it with a rag. Then, follow the fuel line which will run behind the engine to the right hand side of the firewall. Disconnect it at the quick-connect coupler, again, covering it with a rag when you do so. There are also a couple of wiring harnesses that connect to the lower manifold that need to be disconnected. You'll see them, they're pretty obvious.
Now the lower manifold will lift off of the block, after snaking it around a bit. Be very, VERY careful from this point on. You will be looking down at 6 oval holes in the top of the block that go directly into the engine. If you drop anything down in there, you're screwed. It's a good idea to cover these holes with some cardboard/tape until you're done.
Pull the old gaskets out of the top and bottom of the lower manifold and replace them. Use a razor blade to clean the surface of the engine to which they mount. Refit the lower manifold making sure to reconnect the wiring/fuel line, and bolt it in place. Then the upper manifold can go back on.

It all sounds a little intimidating, but you'll be surprised how un-intimidating the engine looks without the intake manifold on. Let me know if you have any questions. I'd be glad to talk you through it if you have any other questions.

 

Nice write up there 310..very handy reference.

 

Thank you for all the excellent info. It sounds very straight forward. I had to swap the intake manifold in my sons Oldsmobile with the 3.8. It sounds very similar. I doubt I will be doing this job before spring but I will definitely ask if I have any questions.

Thanks again, I sure am glad I found this forum, this is a lot of useful information and willing participants.

 

Hey,

where in JTIS Software is written "how to remove the intake manifold"? I search for this but whithout result.

Thanks, Patryk

 

Patryk

On mine I selected Service for the X-Type 2003
Next I clicked on the 'Powertrain' icon (picture of engine lower left corner)
Next 'Engine' icon in the upper right corner
Next 'In Car Repair' which is upper right center icon
This brings you to a list of services and the top one in Intake Manifold 30.15.01

Let me know if this helps.