Not to go against your word but i highly doubt the plenum blew again. I did the plenum with fel-pro gaskets and used a good amout of rtv that way when the metal expands the rtv will move with it and be somewhat fleemsy.

 

I believe the term you are referring to is called "compliance" meaning, the joint remains flexible to accommodate the coefficient of expansion extremes due to either a gross error in material choice or not having design reviews prior to releasing the drawings! I see this all the time here at work. No one looks at the damn drawings! Too much time, too much money it's always some excuse.

Anyway, I have some questions about the adhesive application process:

-what brand of RTV did you use?
-WHAT COLOR was the RTV?
-Bead size: What was the bead size?
-Continuous bead or, sectional application with overlapping joints?
-Applied on BOTH sides of gasket or- JUST ONE?
-Gasket Material: paper or rubber?
-What (if any) chemicals were used to remove OIL FILM at the cleaning and prep stage?
-Was an abrasive method used in prepping of the surfaces?
-What was the cure time of the RTV before putting the vehicle into service?

I have a question regarding intake installation.

Since the intake was removed to gain access to the plenum, were the OLD intake manifold gaskets used or, were new ones installed?

I'm not digging for trouble here, merely thinking about all the cause and affects upon misfire condition and, one that comes to mind is intake vac leak at either injector level or, at head gasket level. Two things in particular come to mind and they are:

1. Coolant leak where, coolant is being sucked into the intake port, thus inducing misfire condition. This can happen if the wrong type of adhesive / sealant is chosen or, insufficient cure time before putting vehicle into service or, absence of sealant around water ports at both the head and intake level.

2. Gross vac leak at intake to head interface.

CM

 

I used high temp RTV. The orange stuff. The plenum was left out over a 24 hour period to cure before installed. Bead size was 1/4" to 1/2" and was continious. Gasket material was paper with rubber sections about every inch or so. the rubber sections were probably a inch long.(fel-pro gasket) RTV was appliedlightly on both sides and the plenum plate was securley fastened tight with RTV squeezed out the sides. All access RTV was removed and yes new Intake manifold gaskets were installed with RTV lightly smeared on both sides. Chemicals used to clean surfaces was (oreilys) Brake Parts Cleaner(evaporates rather quickly) and for the lower plenum gasket a wire wheel brush was used on a grinder. The vehicle was not in use within 24 hours in order for everything to cure. once 24 hours had been up the vehicle was driven but only probably about 10 miles. Then another 12 hours before operating temp was reached. I looked down the throttle body and the bottom plate is still shinny clean from where i cleaned it,no oil residue so no burts gasket at this point.

 

The only issue I see there is, depending on WHO made the RTV e.g. Permatex Ultra Cu, RTV is NOT compatible with rubber and should never be used on rubber beaded, lined, etc, gaskets- ever. The problem is when the sealant comes into contact with such material as rubber, that, it acts as a lubricant, thus, allowing the gasket to slip, or otherwise slide out from under the clamping force. Then, what ends up happening is, separation of the bond line between gasket face and RTV thus, causing weep holes and / or vacuum leaks depending on where used.

The other problem is when torque is applied without letting RTV setup first or, skin over. Under torque, most of the RTV is squeezed out thus, not providing adequate mil-film thickness to produce a robust seal.

Now, even though there are no visual indicators initially, there's always the possibility of a vacuum leak going undetected. Only after a period of time of constant use, does the oil film residue build up to the point of being visible.

Now, if it was RTV made by Permatex and, you went with U-Cu, that's good stuff. Curing is accomplished through moisture and, this product requires torquing while wet vs. skin-over however, I would keep an eye out for separation due to it being bonded to rubber along the gasket. It may tear away from the gasket after thermal cycling over an unknown period of time thus resulting in failure of the seal.

Was it Perm or some other brand?

I just went through and noted this: This is not preferred at all. RTV should never be used as a gasket dressing on intake gaskets. Gasgacinch by Edlebrock why yes, or, even DRY is better than using RTV. THE ONLY places to use RTV are around the WATER PORTS and at 4-corners of the lifter valley to where, the end seals overlap the head seals. It is never to be used near or around any exhaust port either for, it ends up breaking down and creating a nasty gummy mess that coats the inside of the combustion chamber along with creating unseen leaks. The other issue with RTV is removal of it later when the gaskets are to be removed at a later point in time.

I NEVER USE RTV for anything other than the T-Stat housing. Everything on my truck is sealed with either Eddy's Gasgacinch or, Perm Hi Tack sealer (oil pan gasket to block-holds it in place) I only used RTV in the four corners of the lifter valley and, at the four corners of the oil pan and that's it. I loathe removing that crap later.

When using Gasgacinch or similar, it simply wipes off with Acetone or Lacquer thinner - no scraping is needed.

I don't know what to tell you as, who wants to tear down the top end just to replace the sealant but, man, that is really not the way to go there. I'm not harking on you so, please, don't take it as such.

Regards,


CM

 

It was perm. And i should of elabarated onthe RTV usage. I only used very very little RTV on the intake manifold gasket on the bottom only to let it dry and hold the gaskets in place so when i put the stock kegger intake back down they wouldnt slide out.

 

Update and hopefully final fix. I took the ground wire from the firewall going to the valve cover and simply removed it from the valve cover, cleaned it, unscrewed one bolt holding the pcm to the fender and then attached the ground behind the screw on the computer frame. Reattached the screw and bam. No more check engine light. Sometimes you can over look the easy stuff. Thanks for all the help from everyone. yall know your stuff. Im hoping this will fix it for good.

 

I noticed several references to spark plug wires being routed properly. I have a Chrysler service manual for my Durango 5.2L and nowhere can I find proper wire routing. Can anyone tell me where to find it? Tnx

 

http://dodgeram.info/tsb/1998/18-48-98/18-48-98-v8.htm

 

Perfect Zman, thanks