Plenum gasket repair procedure
I wanted to add my piece to this great website since it was so much help for me during a plenum gasket repair. There are alot of threads with this problem, but never one with exact procedure to do the job. Also, I have added what you should be doing once you are already into a good part of the engine work. This thread should contain everything you need to know about changing your plenum.
I've attached a word document containing these instruction if needed. Also, the pictures are included in the file and the links I was not able to post (This is my first post. Must have at least 10 posts to attach links). If an administrator could add these for me, that'd be helpful. Where you see the notes on here, is where the link will be in the word document. Sorry for the inconvenience.
I noticed my '98 ram 5.2L consuming alot of oil with no visible signs of a leak. It also seemed to be losing alot of coolant. I was told if you remove your oil cap while the engine is running and place your hand over the hole and notice vacuum, there's a good chance the plenum gasket is blown. I also found if you look down into your throttle body and notice considerable oil build-up, this is also the case. My truck had a no-start without prior problems due to oil build-up on the spark plugs as well. As for the coolant, the thermostat gasket was the culprit.
What you’ll need:
- Hughes Plenum Gasket Kit Part# 7714
- Intake Manifold Gaskets & Bolts
- Fuel line removal tool (size E) -very important
- Water pump by-pass hose (I made the mistake of not replacing this and had to do the job over to replace it. For $7 it’s worth it!)
- Thermostat & Gasket (Might as well do this now. I have a ’98 and the gasket was leaking bad)
- 2 Worm Gear Hose clamps (For the water pump hose, much easier to work with than the factory hose clamps)
- Thread locker (I chose breakaway strength just in case)
- Inch/lb Torque Wrench (Yes, Inch Pounds)
- RTV Silicone Sealant (For cork intake gaskets)
- Cap, rotor, spark plugs & wires. (Also grab a coil of that plastic conduit for wire protection)
(Follow this link to find the TSB on Spark plug wire routing (see attached file for link) ) <-- Highly recommended to follow this TSB
- Drain about half your coolant
- Disconnect negative battery wire
- Remove Air filter housing/ducts
- Remove throttle body cables (Do not remove throttle body until intake is off)
- Remove all vacuum hoses, PCV, etc.
- Relieve the fuel pressure line. (There's an air valve on the driver side fuel rail)
- Disconnect fuel line using the fuel line removal tool.
- Remove the upper radiator hose at the radiator. (Don’t worry about disconnecting at the thermostat just yet)
- Remove the belt
- Also, remove the idler pulley located right of the alternator for easier access to a pulley bracket bolt. (I would also suggest spraying some penetrating fluid on the belt tensioner and see if it springs back properly)
- Remove A/C unit electrical connections
(There’s a connector with a red tab connected to the wire harness, this will unlock the connector, but the red tab doesn’t come all the way out. After it’s unlocked, push down on the back tab of the connector to remove.)
- Also, the battery lead to the alternator has a clip attached on the bottom of a bracket from the alternator to intake. Remove that.
- Remove all A/C bolts along with the bracket to the intake. (There’s a tricky bolt under the A/C lines, just loosen it enough to get the A/C unit out and leave it on the unit)
- Set the A/C unit on your fan shroud.
- Remove the alternator electrical connections.
- Remove all alternator bolts and brackets.
- Remove the A/C & alternator support bracket, there should only be 6 bolts. (Make sure you’re not removing the water pump bolts!)
- Remove the water pump hose & thermostat housing. (That little by-pass hose might look intact but I had a pinhole leak which I noticed after the work was done. Plus, it’s easier to remove when you know you have a replacement)
- Remove the fuel injector electrical connections & unclip the wire harness from the valve cover bolts. (These are also tricky, try wiggling them loose but if it doesn’t want to go, cut the electrical tape holding the clips and remove the clip from the bolts once the wire harness is free. There should be 3 per side)
- Now that everything is free from the intake, take the time to clean off or vacuum any debris from the area where the wire harness ran. (Also, you might want to check the valve cover bolts, some may be hand tight)
- You should now be able to remove all the intake manifold bolts and free the intake from the engine.
- May be obvious, but you want to cover the center of the engine along with the intake/exhaust ports on the head. (Some suggest covering the push rod area with aluminium foil)
- Clean the old intake gasket away from the heads and intake. Also, where the cork gaskets will go on the block area, there are 2 little holes on the front and 2 on the back sections. It’s a good idea to clean them out, to allow access for the RTV sealant when you install the new cork gasket. I used carb cleaner w/ rags, a scraper and a wire wheel on a die grinder to remove the old gasket.
- Remove the throttle body. (I suggest removing the air sensor at the back or the TB and cleaning that with carb clean)
- Remove the Plenum pan and get ready to see what’s been eating your oil faster than you can fill your tank with gas.
- Replace the gasket and pan using the torque and pattern specs given to you with the Hughes Kit. (DO NOT FORGET TO USE THREAD LOCKER. Don’t want those puppies coming out)
- While everything is out of the way under the hood, this is a VERY good time to replace your cap and rotor & re-route the spark plug wires
- Re-route spark plug wires following this TSB (see attached file for link)(Couldn’t find stock on the wire clips so I just winged it. You might want to install the coil wire after this job is done since it follows the wire harness)
- Now that the intake is out, you might decide you want to port your manifold. I did this and have noticed the engine runs a lot smoother. It requires less throttle to get up to speed which will save on gas mileage. Apparently it also improves torque. The procedure takes more time than actually replacing the plenum gasket. Here are a couple links if you are interested and want to see how it’s done: (see attached file for dodgetalk threads that inlcude pictures)
Note: Injector rails & internal air sensor will have to be removed as to not damage them during this procedure.
(see attached file for links to dodgetalk threads with pictures)
- What we did was remove the divider by cutting it with a reciprocating saw and chipping away the pieces with a hammer and chisel until most of it was gone, then finishing it with a die grinder. Be careful near the throttle body ports as you don’t want to break that part off. We also took around 3/8” off of the runners, and smoothed out the injector ports.
- The throttle body was also shaved. Take away the lips that obstruct air flow.
- Install intake gaskets
- Use RTV sealant along the top and bottom of the cork gasket, and very importantly, where the head and block meet.
- A good idea (thanks to the knowledge of father fxrguy) is to chop off the heads of the old intake bolts and use them as a dowel to align the intake during installation. Only use 3 bolts on the corners (Note: Do not use a “dowel” on the corner near the distributor, leave that corner open as the intake wont slide past that protruding bolt)
- Follow this link for intake manifold torque specs: (see attached file for link to dodgetalk thread) (bolts 1-4 being the middle, left to right. Bolts 5-12 starting closest to center and out) Specifications are simply 72 in/lbs in 12 pound increments.
- Install the new water pump hose with worm gear hose clamps.
- Now everything can be installed in reverse order.
- After everything is assembled, reset the PCM so the readings can be re-programmed. (To reset PCM, leave the battery disconnected, turn the key to run for 20-30 seconds, turn key off and re-connect battery)
- If everything has gone to plan, you should have no more oil leaks, coolant leaks or spark wire arcing.
Last edited by w0rm; 04-09-2007 at 04:16 PM.