Replacing intake manifold plenum

I found a forum post on Jeep Enthusiast Forums that provides the tightening sequence for the 3.8L upper intake plenum of a 2007 Chrysler TWC. Here are the steps:

Remove covering on lower intake manifold and clean surfaces.
Inspect manifold gasket condition. Gaskets can be re-used, if not damaged. Position new gasket in seal channel and press lightly in-place. Repeat procedure for each gasket position.
Position upper manifold on lower manifold.

Apply Mopar® Lock & Seal Adhesive (Medium Strength Threadlocker) to each upper intake manifold bolt.
Install and tighten bolts to 12 N·m (105 in. lbs.) using torque sequence.

Here is the torque sequence for the 3.8L upper intake plenum:

6 2 4
5 1 3

Please note that this information is provided as-is and I recommend consulting a professional mechanic for any further assistance.

You should let a machine shop check it out for warp.

6 spark plugs. They are centrally located in the head. You will have to remove the intake manifold to access the right bank.

UNDER THE INTAKE MANIFOLD

Procedure: 1-Remove Negative Battery Cable. 2-Remove Intake Manifold. 3-Before Removing Ignition Coil(s) Spray Compressed Air Around The Coil Area And Spark Plugs

Well basically, you remove the intake plenum and replace the gasket and reinstall the plenum. Here are the steps:

1. Disconnect the negative battery cable from the remote jumper terminal located at the right strut tower.
2. Remove the air inlet resonator and tube.
3. Remove the throttle actuator cables from the throttle arm and bracket.
4. Disconnect Secondary Runner Valve (SRV), Manifold Tuning Valve (MTV), Throttle Position Sensor (TPS), Idle Air Control (IAC) motor electrical connectors.
5. Remove the electrical connector and the Intake Air Temperature/Manifold Absolute Pressure (TMAP) sensor.
6. Disconnect vacuum hoses from the Secondary Runner Valve (SRV) reservoir, Speed Control reservoir, and PCV.
7. Remove right and left intake manifold supports.
8. Remove support brackets at the intake manifold front corners and MTV.
9. Loosen upper fastener attaching throttle body to support bracket.
10. Remove clips attaching EGR tubes to intake manifold.
11. Remove intake manifold bolts and manifold
12. Remove old gaskets, Clean gasket surfaces, and install new gaskets.
13. Reverse steps to reinstall manifold

You will have to remove the intake manifold (this is the solid large plastic cover that covers the top of the engine when you remove the engine cover). There are many wires and small vacuum hoses to disconnect. Plus.., when re-installing, it is a common problem the manifold cracks if excessive torque is applied to the fastening bolts. And you probably should relpace the intake manifold gasket.You can then remove the thermostat assembly by disconnecting the hoses and loosening the mounting screw.

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The procedure as per service manual is as follows:----

Following the Service Manual instructions, drain the coolant circuit, then remove the return pipe and the short rubber hose connected to the engine main coolant rail (1 clip at the bottom + 1 clip at the top). You remove also the outlet hose (1 clip at the engine outlet spout + 1 clip at the bottom pipe, you need to loosen the pipe mount to remove the hose). Once removed the return pipe you can undo the coolant rail: 2 (tight) bolts below the rail and the oil dipstick bolt holding the thermostat housing. Doing this without the manifold in place is simple, but its not that easy with the manifold on.... once loosened the coolant rail you can remove the thermostat housing. You open it (3 bolts) and replace the old thermostat with new. All 3 gaskets should be replaced, to minimize the risk of leaks. Apply silicone lubricant on the O-rings, then fit housing + coolant rail back in.

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This will help you.Thanks.Helpmech.

The distributor firing order on a v-6 is 1-6-5-4-3-2. Looking from the front of the engine with distributor cap in place the #2 distributor tower should be looking at #6 cylinder on engine. On a v-8 the firing order is 1-8-4-3-6-5-7-2. Looking from the front of engine the #1 distributor tower should be looking at the #8 cylinder on engine. Both distributors turn in a clockwise rotation. Hope this will help you.

Not alot you can do but remove the intake plenum and have the gasket replaced.

Quest#1 Your intake manifold is leaking
Quest#2 Yes
Spray carb cleaner while running at intake manifold gasket , both sides, and check for a difference in running condition while spraying to confirm leak here. Replace all intake manifold gaskets and plenum gasket.
If this does not confirm intake leak , have the Throttle Body cleaned manually by a professional, or yourself using specifically" Throttle Body Cleaner "

My 2002 Land Rover Freelander V6 thermostat crapped out as well and I decided to replace it myself.

The plenum is deceptive, but after 3 hours of looking and trying I finally got it off. Of course there are many hoses and electrical connections that need to be removed, but that's the easy part because you can see them all. The bolts that hold on the plenum are what your worried about and I will now tell you where they are. Read this and you should take about 30min to remove the plenum.

There are a total of 6 bolts to be removed that secure the intake plenum to the intake manifolds.

First remove the 4, 10mm large and obvious bolts at the top of the plenum. Now here is the tricky part, there are 2 bolts that are at the back of the plenum near the fire wall. As you are looking at the intake plenum from the front of the car, they are on the back side of the plenum near the fire wall on the passenger and driver side of the intake plenum.

Both bolts your looking for are 8mm bolts. If you remove a 10mm bolt, your removing the bolts that secure the rear spark plug coils.

The driver side rear intake plenum 8mm bolt is secured to the plenum itself. Fell with your hand about the back of the plenum on the right side for a lone bolt that is in the plenum with a metal tab that goes down to the back of the rear cylinder head. Remove the bolt that is attached to the intake plenum, not on the rear cylinder head

The passenger side one is a bit different. Feel on the back of the intake plenum about the passenger side for a metal support tab that comes down from the intake plenum and secures to the rear cylinder head. Where the support tab attaches to the head is a 8mm bolt that you remove.

Now here come the leap of faith. If you have the 4, 10mm obvious bolts removed and the 2, 8mm from the rear of the plenum removed, and if you can rock the plenum up and down about 2-3 inches,but it still feels like its attached to the intake manifolds in the middle of the engine, then you have removed all the bolts that secure the intake plenum to the engine. This is good.

The intake plenum is now being held on by the rear intake manifold by 3 O-ring gaskets. Push onto the back of the intake plenum near the firewall to expose a gap at the front of the intake plenum at the front intake manifold. Put 2-3 long flat screwdrivers into the gap or a small pry bar, and ever so gently but forcefully, apply prying force as to not damage the mating surface of the aluminum intake manifold, until the intake plenum pops off. It will just POP off.

Now that the intake plenum is popped off, take careful note of all the electrical plugs and hoses as to where they attach. You will not need any tools to disconnect the electrical plugs or hoses. To remove the hoses, push down the red ring with you fingers that the hose goes into and pull on the hose, it should come out very easily. The electrical connectors, push on the metal clip down and pull the connector loose. The electrical connectors only plug into their own plug, so you cant mess them up.

Tools you will need to replace the thermostat;

1. 8mm combo wrench. Make sure its not too long, shorter is better.
2. 10mm socket, shallow. 10mm combo wrench
3. 2-3 flat screwdrivers, for prying off the intake plenum
4. Ratchet wrench
5. 1 foot long worth of socket extensions. 2 6inch extensions will work as well
6. Universal socket joint
7. Angled needle nose pliers make it easier for hose clap removal, but straight needle nose pliers will work
8. Diagonal cutters to cut securing zip ties for the wiring harness

Take you time, once the plenum is off it goes pretty smooth after that. We removed just the forward intake manifold and that was more than enough clearance to remove the thermostat. You do not need to remove the fuel rail or spark plug coils from the manifold but you will need to disconnect the electrical connections to move the intake manifold out of the way.


Take pictures, there's a lot of hoses that go all over the place. The electrical connectors are only long enough to go where their supposed to go.

Then take that UK piece of **** to the dealer and trade it in for anything made in the USA or Japan. Changing a thermostat in any of those will only take 10 min and require 1 tool.

Repair provided by KPCYCLES.com of Honolulu, HI