Fellas,
My 1985 stock 2.5 Duke valve cover has a MAJOR problems😟. I was reading on PFF that the stock Pontiac 2.5 Duke valve cover gasket is prone to have an early failure. In my case, it can no longer hold in the engine oil. I replaced the stock rubber gasket with a new cork FelPro gasket. Naturally, I ‘held’ the gasket in place with the highest quality gasket sealer. [I forgot the brand name. HHowever, I did pay O’reilleys for “the best they have to offer]. It still leaks.
Is there a manufacturer out there that offers a high quality valve cover? I understand that because the Duke was not a performance engine, per se, it may be difficult to find a high quality replacement. However, I do believe that there must be a manufacturer that does (offer) sell a good quality one. Does anybody have a suggestion?
Cordially,
kevin

[This message has been edited by kevin (edited 12-19-2018).]

Hey Kevin,

I recommend first inspecting the valve cover itself. The original stamped steel ones are prone to getting bent and once they are, they're damn near impossible to get to lay truly flat along the gasket.
Good news is that you can get an aluminum reproduction version (identical) through most suppliers like rockauto and even Fiero Store.

On the gasket issue, I highly recommend going with the Felpro Permadry or Permadry plus. You install it dry with NO rtv sealant. Its held up well on mine. It has a rigid metal core that assists and is the best gasket for the replacement (but thats my opinion). I use them in all my other road and track cars.

you want it Never leak again ? throw out the gasket, thoroughly Clean both the valve Cover and HEAD surfaces. then put a BEAD of "Permatex Gasket Maker" on the head, a then coating on the valve cover. put it on, loosely install the bolts (by that I mean , don't torque them down just a little more than finger tight.) just enough so the 2 surfaces are in contact. let it sit for a day. Once it dries It Will NEVER Leak again !

I never had problems installing any valve cover gaskets. Not even on old Ford 2.0l and 2.5l overhead cam engines.
Most have problems mainly because:
Way over tight and wreck gasket and cover.
Do Not Clean all metal of all oil and sealers won't seal.
They Do Not allow RTV silicon to "dry" before running the engine. "Dry to touch" is not same as total set time that can be a few hours to 1-3 days depending on several things including exact RTV formula used.

Worse is many use way too much RTV, w/ or w/o gaskets, and "boogers" in the engine can block drain holes etc and have more problems.

I used cork and rubber caskets w/ Fiero before w/o problems but Felpro PN VS50179T PermaDryPlus is far better for this engine.
It a "New" silicon gasket and parts to seal w/o crushing/bending. Come w/ new bolts etc and install gasket dry.
Follow directions w/ it and if bolts/holes are oily/dirty do not torque in FSM or will wreck cover, break bolts, etc.

If cover is damage beyond help and many are because morons bent the seal face several to many times by now.
New cover w/ a new cap is Dorman 264-905

Note that Dukes had 2 valve covers used at the factory.
One is made for gaskets. One made to work right w/o a gasket, just RTV silicon.
One for RTV have folded metal on bolt holes and "dents" on flat areas to maintain the correct gap for the RTV.

Felpro # above is made for either type and works w/ Dorman cover too. (Think Dorman is made for RTV too but not looking at my car at night.)

------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave

As others have said, the big problem is that people tighten the snot out of the bolts, and bend the cover lip/flanges.
If you lay the cover flat on a work bench, and take your time, you can hammer the lip flat. I think I used a socket extension as a "peen".
I used a blue FelPro silicone gasket. Don't remember if I used sealer or not, but it can be done correctly. Mine hasn't leaked a bit since I replaced the gasket. (The rear main seal is another story...)

quote Originally posted by Raydar: As others have said, the big problem is that people tighten the snot out of the bolts, and bend the cover lip/flanges. If you lay the cover flat on a work bench, and take your time, you can hammer the lip flat. I think I used a socket extension as a "peen". I used a blue FelPro silicone gasket. Don't remember if I used sealer or not, but it can be done correctly. Mine hasn't leaked a bit since I replaced the gasket. (The rear main seal is another story...)

Ones made for gaskets is easier then later years for RTV only. Folded edge metal at holes make them harder to flatten right.
Many have been hammered so many times that the metal is weak and doesn't stay flat even when carefully installed.

the Felpro # I listed above also have load spreader and why needs new bolts that come with. Even the small spreader make a big difference. You could add spreader and new bolt to rubber/cork but you still have rubber or cork.
Most pictures have all "washers" shown. You only use half or 1 set for which cover used. 1 set for gasket cover the other is for RTV only cover. "Washer" plus metal in the gasket sets pressure loads with each type cover. Directions tell you but just seeing is a little confusing.

New cover are "update" version w/ new cap required. The cap seals much better then old ones even w/ new "old style" caps from Stant etc. Have new grommets too for PCV.

Dorman cover "kit" ~ $50 and Felpro "kit" ~ $14 to 21 is far less then just the cover alone from TFS @ $90 then $10 for the cap required add shipping cost and they don't carry the Felpro "kit" but gaskets they do have cost almost as much as the kit ($11-13).
You can order both at many local parts stores and not pay shipping but get same or next day ship to store at most of them. (Order in the morning to try to get same day.)

[This message has been edited by theogre (edited 12-20-2018).]

The BEST valve cover gasket you want to use on the Duke is Felpro PN FEL-VS50179T
This rubber/steel gasket has raised edges to seal properly and comes with all the hardware needed for installation.

------------------
My World of Wheels Winners (Click on links below)

3.4L Supercharged 87 GT and Super Duty 4 Indy #163

fierosound,
Thank you a whole bunch for your gasket information 😊! My next question involves interchangeability. Specifically, did GM use the exact same manufactureing dimensions for all the Duke’s produced? Can I use a 2010, 2009, 2004, 2007 etc. GM Duke equipped car and transfers that car’s valve-cover onto my Fiero Duke’s engine?
If so, I believe the newer designed Duke’s manufacturing upgrades, over the years, are (should?) be a great upgrade? Can anybody confirm and/or elaborate on this idea?
Cordially,
kevin

[This message has been edited by kevin (edited 12-20-2018).]

87 to 91 or 92 Duke VIN R engine have major changes and major work to swap in an older car. GM doesn't make these after that.
Only a few Minor parts like valve cover can use on old dukes.
See my Cave, Duke Quick Ref

I've used RTV exclusively on my 84. Never had any trouble, but yes the secret is to not over tighten the bolts.

(I have a gasket like the one shown by FIerosound on my SD4 engine and it 'weeps'. No big leaks, but for me, it didn't seal as good as the RTV did on the stock engine)

quote Originally posted by edfiero: I have a gasket like the one shown by FIerosound on my SD4 engine and it 'weeps'.

The problem is with the Edelbrock valve cover (I assume you have one).
The bolts are now "inside" and oil migrates around them.
I put thin smear of RTV around the bolt holes before bolting it down.