How to: Intake Manifold Gaskets 1995 Grand Prix

[spacepiston]

GTP Dad produced a nice little write up that I used to change my intake manifold gaskets this week. I found very few solid resources on the internet outside of his write up. I did note a few missed steps though.. I decided to revise his version with extra steps that I feel could help future people with a 93-96 3.1 Grand Prix

It is not difficult to change an intake manifold gasket but it will take you 5 to 15 hours depending on skill. First you must disconnect the battery.

Drain the coolant from the radiator. (Twist the drain cock 1/4 turn counter-clockwise and pull).

Remove the air cleaner tube from the throttle body. You will need to remove the top radiator hose from the engine. It may be a good idea to replace the thermostat so disconnect the hose where it connects to the top of the manifold.

Remove spark plug wires from coil packs. Use tape and mark them accordingly. It is possible to simply allow the wires to hang off the spark plugs without having to remove them from the engine compartment. They don't get in the way down there.

Remove coil packs. Label and disconnect wires carefully. Be extra mindful of the coolant temperature sensor located on the block near the tranny fluid dipstick. It has a green wire, which snaps off easily... It's a good idea to start labeling all your bolts too. This saves a lot of time on reassembly!

Now you will need to remove the associated hardware that will prevent removal. Take the belt off. Remove the plastic belt guard. Remove wiring from alternator. Unbolt the two black metal support brackets attached to the plenum. Remove alternator mounting bolts. You may have to remove the entire mounting bracket which is 2 pieces of metal held on by 4 bolts. The 4th bolt is between the engine and the firewall and is difficult to see.

Unbolt the power steering pump/resevoir. You can turn the pulley until the holes expose the 3 mounting bolts. Do not remove! Simply drape it out of the way.

Unbolt the "dog bone" pipe that runs from the top of the water pump between the engine torque straps and the valve cover. This will be in your way you have to at least pull it out of the water pump so you can create clearance for the valve cover to be removed. There is an o-ring that should be replaced but I used rtv.

Unbolt the the EGR flex pipe. You should be able to pull it down off the control there and move it out of the way. RTV works great here too.

Remove throttle and kick down cables and bracket. Remove any remaining hoses or wires that obstruct removal of the plenum.

Remove plenum. Be mindful of any drivability controls still nearby.


Release fuel pressure. There is a shrader valve on the end of the fuel rail which is easy to find. Be very careful not to damage the rails or the threads when you remove the fuel line. Be extra careful not to lose the o-ring on the fuel inlet hose. It takes a bit of pulling to get the end out of the rail and my o-ring popped right off. I saw it briefly as it disappeared into the motor. It's 7 bucks from the dealership.

You shouldn't need to remove the fuel rail or disconnect the fuel injector wires. Just isolate the wiring harness from the rest of the block and leave it as is.

Now is a good time to get those valve covers off because they are bolted to the head AND the intake manifold. Be careful of debris.

Once everything is loose take a socket of the appropriate size and loosen the manifold bolts. Start in the center and work your way in a cris-cross pattern going toward the outside of the engine. Once everything is loose remove the bolts and place them in a bag or tray so you don't lose them.

Now, gently pry the manifold loose from the front of the engine. I found the thermostat housing on the back end of the manifold to be very convenient at this point. A light tug quickly freed the entire manifold. Once loose remove from the engine and place aside. I had lots of leaves, dirt, and nutshells on top of the manifold..be very careful of debris falling into the motor! Place paper towels in each port and lay a shop towel or two in the lifter galley. This will prevent any gasket or other material from dropping in the ports or galley that could damage the engine.

It will be necessary to loosen the rocker arms for each push rod that extends out in front of the intake gaskets. There should be 3 on each side. If you back the nuts off a ways you can just turn the arms out of the way without completely removing them. Remove the 6 push rods being VERY VERY careful to label their exact location. Remove old intake gaskets. Note that they suck.

Scrape the gasket surface with a gasket scraper to remove the old gasket. Wipe the surfaces clean. Get all of the old gasket material off. Take time to remove ALL the old rtv from the ends of the block where the manifold makes contact. You want all your surfaces completely clean and dry. If you bought a gasket Kit you will note some extra o-rings. The big reddish orange o-ring is for the oil pump shaft. Right next to the thermostat housing is a round cap with a hold down bracket. Remove the bolt and bracket. Pull the cap straight up to remove the oild pump shaft. This was in there quite tight on my car. The seal was definitely leaking though. Replace O-ring on shaft. Reinstall (which might be difficult. I had to use a rubber mallet to get it back in.

Assembly:

Install new lower intake gaskets. Apply RTV sealant or whatever came in your kit to both ends of the block where the manifold makes contact. 8-10 mm bead will be good. Get it in the corners good to be sure of a good seal.

Reinstall push rods and torque to spec (I believe about 20 ft lbs)

Replace the manifold by placing it straight down. Don't twist it or move it excessively as you may dislocate the gaskets and cause a leak.
Replace the bolts and torque to specification in a pattern designated by the manufacturer:

4 top bolts to 5 ft lbs
2 side bolts to 5 ft lbs
4 top bolts to 10 ft lbs
2 side bolts to 18 ft lbs

Blue or Red thread locker to ensure bolts do not vibrate out. I let the RTV cure for a few hours, but it took longer than that to reassemble the car.

Hook up everything you disconnected and fill the radiator with coolant.
Do an oil change because you are sure to have some coolant in the motor.

Reconnect the battery and you should be able to start the car. Run it up to operating temperature and check for leaks.

I found the Chilton's manual to be of no help for this project. GTP Dad's how to got me by and I've never been this far into a motor before. If the car is a GTP forget the whole thing if you are a novice and have her take it to a repair shop. Good Luck!

Hope this update helps others!

[richtazz]

Use blue, not red threadlock. 95-96 motors had two types of rocker arms, both requiring a different torque value. Change the t-stat while you're in there. when replacing the oil pump drive o-ring, also install a small block chevy paper gasket (Fel-pro part number 70194) between the top of the housing and engine block for added insurance against future leaks. Cleanliness is next to Godliness when doing this job. Finally, use a torque wrench calibrated in inch pounds, as ft/lb torque wrenches aren't very accurate at the lowest end of their scale.

[bluegreen]

I have a chilton book and it is crazy. I got everything back together and the fuel rail is leaking. We took the inlet line off and there was no oring. we bought one and put on it but we have no reference of where it goes. It still leaks. Any one have pictures or help of any kind.
thanks