Hey everybody,

I am about to replace the plenum gasket and intake manifold gasket on my 98 5.9L motor. I have the Haynes manual for the truck and I have gone through it and it says to use a RTV make-a-gasket when installing. However, I just got the gaskets from the dodge dealer and they said it is not necessary because it is now a foil gasket rather than a felt gasket with a silicone bead (according to them that is what came in it originally). So, I was wondering if anyone knows if they are right and that I don't need the RTV sealant. Also, if anyone has any insight on this project, helpful hints, pitfalls to avoid, it is certainly welcome. It seems to be a fairly involved project that I would prefer to only have to do once!

Thank you in advance,

Mike

 

if it is a dodge gasket, you do not need any sealant, it is the same as the thermostat gasket, just put it on, and torque it down in the correct sequence. I did this job last summer and will be doing it again in a few weeks (swapping heads) and it is not too difficult.

here's a link to the TSB on it...plenum repair have a look.

 

Thanks for the info. I was also wondering if aftermarket intakes (edelbrock or others) still have a plenum pan at all?

 

no they dont, however they don't bolt up to the magnum head (as is anyway). You can buy an Edlebrock head and have it drilled for both old style manifolds and the magnum type manifolds. the only bolt on option for the magnum engine is the M1 from Mopar performance.

 

I'll be doing this soon. I got a stock throttle body off Ebay for $50 and I'm modding it the same as a Fastman or APS (I love having free access to a machine shop). I'm also milling out the intake runners on the intake and putting the APS aluminum plennum plate on it. I spent $10k on a truck so I wouldn't have to work on it... Damn thing anyway...

Anyway, good luck with the project!

 

LMAO... Todd, I was just thinking the same thing yesterday... paid 12K so I wouldnt have to do too much to it... yeah right!

Are you going to cut the runners all the way down? (per Mikes recommendation in the thread) I'm tempted to go all the way down as mentioned as well as the R/T heads which I should be ordering today. Hopefully they'll be here within 2 weeks so I can get my truck done.

 

Don't know Steve. Gonna take it apart and decide once I look at it. Depends on how hard it is to clamp into a Bridgeport mill too. I am definately polishing the runners, but I'm not going to port them at all. Wish I still had access to a Dyno.

 

One guy found that if you lay the manifold on it's side, you can take a sawzall and cut the runners out that way. I might do this, then take it to a machine shop and let them clean it up along with the injecter bosses.

I cant wait to get my truck finished!!!

 

It's funny, I don't have a sawzall, but I do have access to a Bridgeport mill complete with ProtoTrax CNC capability.

I'm gonna look at the intake once I have it apart and see what I think. I'll polish everything by hand in my shop at home. I have the die grinder and stones there to do it. I'll do all the machine work to the throttle body here on the Bridgeport, and hand polish it at home also before installation. I'm gonna mod the TB before I take the truck apart though.

I'm looking forward to having my truck done too. But I've come to learn that it'll probably never be done. I'm sure something else will go to crap soon after I get this done.

 

I am happy to say that I'm finished my plenum pan gasket! While I was in there, I cleaned my injectors, replaced the O-rings on the injectors, replaced the cap, rotor, plugs, wires, thermostat, all the gaskets, and a couple of radiator hoses that I had to cut off. My truck runs like a million bucks now. Its a great feeling to have my truck feel powerful again.