1980s Help with knocking sound from valve cover - 81 Fleetwood V-8-6-4 (with videos)

[chrisbutnut]

There is a knocking noise coming from the passenger side valve cover.  I removed the oil cap and there appears to be some sort of a plastic piece inside that covers the valves (or prevents me from seeing the valves underneath it).  When I stick my finger in the hole, I can move that piece back and forth.  That has to be what's making the noise.  The engine seems to run fine otherwise, and I am not able to see anything in the service manual that might identify what this piece is.

Video of noise, engine idling:  https://youtu.be/pubtT1pAOSI

Video of oil fill cover removed:  https://youtu.be/UQdxATdFp5I (you'll have to turn up the volume to hear the piece moving)

Any ideas? 

[Big Fins]

Pull the rocker cover and eliminate a lot of guessing. A set of gaskets is cheap.

[chrisbutnut]

Right, but these are plastic valve covers, and thus traditional cork gaskets are incompatible.  I'll have to have my mechanic do the work, but figured someone might have an idea based on the videos.

[Big Fins]

Okay. I'll act surprised and say, 'Plastic covers?' That's as bad as having a plastic oil pan. I honestly was unaware they were plastic.

[TJ Hopland]

I don't think I would run it till I knew what that was.  It doesn't sound terrible now but what ever it is isn't right and if its not all the way loose or off or broke now you would have for it to get that way and fall into other moving parts and cause a bunch of damage. 

There are baffles in the cover to direct fumes and oil where they need to go.  I wonder if those were maybe glued in and have finally let go?   Typically there isn't one by the oil fill hole but that ain't a typical setup there.  Maybe there are (or were) some funky baffles to guide fumes or oil into or out of the big bulge areas where that deactivation stuff lives?  And one of those fell out?   It sounds more plastic to me but that could be a metal part just rubbing on the plastic and there are quite a few parts in there.

Its been a really long time since I was in one of those and just don't remember much about the covers themselves other than they were full of cracks and kinda brittle even back then. 

[chrisbutnut]

@TJ Hopland , I think a baffle is exactly what it is.  I looked in the parts illustration manual, and there are either one or two baffles under the rocker cover.  I guess my concern is what I'm going to have my mechanic do when he removes the valve cover.  If the baffle(s) is/are glued in place, does he glue it back?  Are there parts available? 

I'm definitely concerned and agree that I shouldn't run it until this is addressed.  I guess I will have to have it towed to my mechanic.

[TJ Hopland]

The fact that they show them as separate parts and no fasteners kinda makes me think that either they just snapped in or are just kinda stacked in there and maybe not really firmly attached. So then the question is did some little tab or the part itself crack and that is letting it flop around?  Or does plate 77 have some sort of issue so item 78 isn't being held in the proper position?

Is item 13 a gasket?  Those I think are the ones I remember being a soft(ish) foam like material and fairly thick because the solenoids didn't seem to sit at a specific or consistent height.   

[chrisbutnut]

Looking at the parts catalog, #78 is for my engine (368-9, which is the fuel injected version with modular displacement).  Part # 77 is for the 368-6, which is the carbureted version (1980, I'm guessing?).  I'm not sure what part # 13 is. 

I guess the only way to figure it out is to pull the valve cover.