I must say that this Thread was very informative, and at times very entertaining. I just received my Hughes Kit today, and plan on doing this job this weekend. Thanks Fellas, and especially you Silver for writing the DIY.

 

Who even said that the original plenum gasket and plate lasted 160,000 miles? You may have just started feeling the effects of it leaking badly, and it has been leaking for the past 100,000 miles.

 

OK im still fine with replacing it again 50K miles from now! Id be happy to get another 50k out of it. Im at 169,500 now. Replacing it also gives you a chance to ee what everything looks like inside your engine. Along with the plenum gasket im also replacing the throttle body gasket, water neck gasket, thermostat, valve cover gaskets, all new injectors, new heater core hoses, all sensors that are in the manifold, and the bypass hose. Why not, im in there i may as well do it.

 

you are contradicting yourself here.... you don't wanna replace a part that is gonna fail sooner than you think, yet you are changing injectors and a bunch of sensors 'while you're in there'? Why not fix the plenum the right way 'while yer in there'?

 

Im replacing the injectors cause they have 170k miles on them. Sensors cause they are a few bucks. The plenum plate is not worth $100 to me. Atleast not at this point in time.

 

Well, by time you buy all new bolts for the intake manifold (because you do know that you can't reuse them) and all new gaskets, you're not going to be far from the cost of the alum plenum kit which includes all that stuff. FYI, the bolts are not real cheap, and I think the only place to get them (besides Hughes or APS) is a dealership or other Mopar parts seller. You can do what you want obviously, but you're not really saving much by skimping and putting in a part that WILL fail on you again.

You might consider shortening the plenum pan bolts (or getting new ones that are shorter), or tapping the plenum pan bolt holes slightly deeper. This is believed to be the main reason the gasket fails, the bolts aren't torquing the pan down sufficiently because they are too long or the holes to shallow. Then when the alum intake and the steel pan heat and cool at different rates, the gasket is able to push out because it isn't tightened enough. At least if you did this, it might not fail on you again.

 

It cost me about $35 for 16 injector o-rings, manifold gaskets, throttle body gasket, water neck gasket, and the throttle body gasket. The o-rings will be returned because i decided on new injectors which come with new o-rings. That will get me about $12 back plus tax. I know all about the bolts for both the plenum plate and the manifold itself. None will be re used just like a head bolt. I plan to use bolts about 1/4" shorter. Ill buy grade 8 at home depot. Yes of course thats overkill but thats ok. Ill also be using thread sealer on them. Something about bolts hanging over the cam, crank, rods, just doesnt sit well with me. I use ARP liquid thread sealer on everything. I also plan to use a super thin bead of high temp RTV around the water passages on the manifold and heads and all around both sides of the plenum plate. Ill let the plenum plate dry for 24 hours before installing the manifold. Once the manifold is installed, i will not be filling the block with antifreeze or running the jeep for the same 24 hours. You guys are prob all like WTF all this overkill but no aluminum plenum plate? LOL yea i know i know but with the mileage i have i expect to take it all apart again soon enough anyway. When that time comes it will be between 400-450 horse when it goes back in. Till then im good.

 

Ok I have read this tread from beginning to end and have a few questions. Is the plenum leak more prone to the V-8 or can it happen to the V-6? I have a 2003 Dakota with a 3.9 and recently noticed a sudden drop in MPG and Oil consumption went up. I also noticed there is an oily film at the bottom of my intake. leading me to believe that my intake needs to be fixed. I have a spare intake off of a 99 3.9 that I did this mod to it in the hopes of installing it in the event my plenum ever leaked. I'm looking to gain more MPG that anything since I put 30,000 plus miles on my truck a year using it mainly for work and HP is not high on my list of gains I'm looking for.

So I guess what I'm trying to say is has anybody ever tried this on a V-6 before. Obviously there will be some sort of gain to be had but I was wondering if I'm the only nut job doing it.

 

V-6 is same style manifold, so, same problems. The symptoms you are talking about sound an awful lot like a blown plenum.

 

That plenum fix guide link is broke, is there another one? I can not seam to find a search box.. ROFL or I would look my self.

I am the same as above, I have a question, I have the same sort of problem as he describes, but it seems more like the manifold is sucking oil in through the PCV and the other vent that connects to the air intake hat. You can see a run of oil.. I actually replaced the hoses and new pcv valve.. and it was opening/closing like mad.. annoying little plastic crap, got a metal one that would fit and works much better, so I know for a fact it is sucking oil in.. and judging by those pics on the net it seems these seem to do that naturally.

I need to do a valve cover job, while I'm in there my dad and I are going to make sure the oil drains are not clogged...

So will this plenem leak cause what kind of running problems? What are the symptoms if you really need to dive off into a repair on it?

I do have a weird problem...
https://dodgeforum.com/forum/2nd-gen...ml#post2374869

But I'm not sure if that would be causing it.. any help would, I would be grateful.