: Plugs/Wires check! EGR check! Phenolic plates???

05-23-05, 06:05 PM
Ok, so far based on info I've gotten here (many thanks!) I've gotten two of three of these jobs completed.


On the 94 STS, the engine cover has four bolts which hold it down. Supposedly, taking these bolts off will remove the cover and allow access to the phenolic spacer plates for cleaning.

My problem ( with apologies to spyder who's tried to help) is that on the air intake side there's a bracket attached which prevents the cover from fully disengaging from the engine. Attached to the bracket are a variety of parts which complicate the removal process.

I would greatly appreciate anyone's help who has removed the cover to walk me through this procedure. Or, if it's not required to detach the intake side bracket, how else do you get at the plates?

05-23-05, 06:57 PM
You don't want to remove the silver top cover. The phenolic plates are not under the cover. They are under the intake manifold itself. The phenolic spacer plates separate the intake manifold from the cylinder heads. They act as an insulator and have the passages for the EGR and PCV feeds to the individual cylinders in them. Take the 4 inner bolts out and remove them. They are about 6 inches long. Lift the entire intake manifold up off the engine. If you leave everything attached to the intake (the air duct, etc) you can just tilt the intake manifold up on one end to access the phenolic spacer plates. The whole intake manifold, throttle body, bracket, etc. all lifts up a little. Tilt up the intake with the end behind the power steering pump the highest and just block it up with a block of wood to hold it while removing the plates on each side of the manifold....one phenolic plate between the manifold and the head on each side. Clean the plates out thoroughly and clean the intake ports at the mounting surface to clean out the little "mouse holes" or notches machined into the cylinder head material itself.

To actually separate the silver top cover from the manifold and lift it up you have to take out the perimeter row of screws in the top cover...but you really don't want to do that for cleaning out the phenolic plates and it isn't necessary at all. Just take the 4 inner bolts out and the whole thing will lift up. There is no coolant or other fluids in the intake so there are no passages to worry about or gaskets to replace or liquids to spill.

05-23-05, 07:34 PM

I've had the four bolts out, but it didn't seem that there was a ton of room to 'tilt' the manifold. That bracket on the air intake side seemed, at least the first go round, to be holding the manifold down tight.

I'll give it another go this week. Once I found the EGR valve, that was an easy fix, so I'll take your word for it every time.

BTW, no service engine light since the WOT runs and changing out the plugs/wires.

This forum should sponsor your participation.