How to properly fit a 504/505 rocker cover

callipygous

callipygous

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Fellow Frogger
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Hi,

Been trying to fix a leaky rocker cover the last day or so, so off with the turbo... (not a quick job)
After getting a good (new to me) rocker cover and new gasket, plus all new spark plug rubbers and the bolt rubbers, the rocker cover was refitted with a smear of Permatex form-a-gasket (aviation) on the rocker cover and smooth surface of the gasket.

Thought all was well and that the leak may be eliminated when I found this:

gasket-showing.jpg
If you look closely in the image you'll see that a significant portion of the new gasket is showing, i.e not giving it's full surface area sealing... Is this normal? I mean the gasket is pretty wide and the rocker cover is sitting properly on the cylinder head. Fingers crossed there will be no leaks? Or should something be done?
 
Doesn't really look correct to me. As far as I recall, the metal cover sits much lower, and you shouldn't be able to see any rubber at all. What's it look like on the top side ? Just compare it to all the other sides.

Is it possible that the side you have shown has twisted 90 degrees while you were fitting it ? I think that happened to me once.

And it is the correct gasket for that engine ?
 
I always very lightly nip the two cover bolts then wriggle the cover around to centralise it, then nip it up finally (I think you may need to move the cover upwards towards the carby side). It does not need to be too tight and I have never used any sealant (Not in 45 years anyway).

Good Luck

PS still have not seen Dyno sheets for your car.:wink2:
 
The gasket has fallen out of its correct location, as it is it will damaged by the edge of the rocker cover and will certainly leak. You shouldn't use any sealant, although a small amount on the upper face will help keep the gasket in place while you fit it, wait for it to cure.
 
DSC09673.jpg Still think it may only need cover centralising. :)

Have added pic of my non-leaking cover fit.
 
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Thanks for all the replies. I'm pretty sure the gasket hasn't fallen out, but just has some annoying overhang...

Did try centralising the rocker cover, but unfortunately, the spark plug tubes don't allow for much (1 mm perhaps) of movement. Car is almost together and hoping for the best.
 
I agree with Graham....it has twisted and / or fallen out of the correct location.

Here is a photo of the topside of my 505 SR (carby model). And topside is the same as bottomside.


Notice that no rubber gasket is showing...at all. The metal cover is slightly overlapping the head.

The gaskets for these are quite thin, really....think back to how far out is protruded when you were slotting it into the cover when it as off.

Top 1.jpg

You're going to get a lot of oil coming out when you start that engine, unless the reason you can see so much rubber is that you have some strange non-standard tappet cover or the wrong gasket...
 
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I normally use contact glue to glue the gasket to the perimeter of the rocker first, let dry, then fit to cylinder head.

But as others have said, in your case the gasket has moved/twisted along its length.

I'd be removing it and starting again.
 
So would I. I've found that those gaskets can come out a bit on installation. A light smear of gasket sealant etc will prevent this from happening.
 
Geeeze! Memories of the nightmare air-cooled VW situation!

As you probably know they didn't use studs & nuts to hold them on- they use a big metal clip. Teutonic efficiency??

And, of course, when you used a big screwdriver to lever the thing up the gasket moved and leaks occurred.

I ended up cutting some 5-ply plates using the rocker covers as the profilers.

Then I used gasket cement (Hylomar) on the rocker cover side of the gasket & clamped them in a vice till the cement set.

Never had a leak after that.
 
Pug72 said:
I normally use contact glue to glue the gasket to the perimeter of the rocker first, let dry, then fit to cylinder head.
Click to expand...

John Palmer, a very experienced Peugeot mechanic in Brisbane, used to do this. He said he never had one leak because of the contact cement.

What causes these rocker covers to leak is :

1) People don't replace the little rubber sleeves (inside the cover) which go around the two bolts which hold the rocker cover on.
In this case the cover leaks but the oil appears from the bottom because it has run down through the two housings which are tack-welded onto the tappet cover, and through which the two bolts go. Then people tighten the bolts because they think that the oil is coming from the gasket, but it isn't. The tightening causes problem #2.

2)...them being warped due to someone tightening them down too much....which happens often. Oil then comes out from between gasket and cover. Once they are warped they cannot be unwarped. You need a new one, or else just use gasket-grade silicone like me.

I know that technically the gasket needs no gasket goo (on account of the many ribs, or lips, on the bottom side of it), but these days I always use gasket-grade silicone. I got sick of leaks ! There is no real reason that silicone is bad (apart from if you use too much, and a bit gets into the oil....though even then it gets picked up by the oil strainer at the bottom of the engine).....it is just that technically it is not needed. But they're getting old these days and a bit of silicone really sticks on the cover.
 
No, it's fallen out, will take you 3 minutes to pull the cover off and then you will see what I mean.

callipygous said:
Thanks for all the replies. I'm pretty sure the gasket hasn't fallen out, but just has some annoying overhang...

Did try centralising the rocker cover, but unfortunately, the spark plug tubes don't allow for much (1 mm perhaps) of movement. Car is almost together and hoping for the best.
Click to expand...
 
Thanks everyone for your replies. The turbo was back on the car (it obstructs the rocker cover from being easily removed) so I took the chance and started it. NO leaks from the rocker cover! Horray! Drove it about 80km and it seems fine.
 
Alriiiight.....

Please tell me, just out of interest....do you have a standard rocker cover ?

And more importantly...can you see just as much gasket on the top side as on the bottom side (which you pictured) ?
 
It's just a 504 rocker cover that I'm using, I'm pretty sure it counts as standard. Of course, it could be a 404 rocker cover for all I know. I think 404/504 and even 505 rocker covers are the same (with maybe some power steering studs). I could be mistaken though.
No, you can't see as much gasket on the top (carburettor) side, it's a lot better fit on that side.
 
I'd spend the time to remove and replace the rocker cover despite the current no-leak status. Things like that can come back to bite you on the bum.
 
I think these things just don't line up properly on some cylinders heads...got another rocker cover, test fitted a gasket, put it on a spare cylinder head that was laying around and noticed a gap on the inlet side this time. Maybe it has something to do with how the spark plug tubes are installed?
 
Gap on the inlet side ? :crazy:
With all due respect, Callipygous, I can't see how that is possible. Normally the cover sits flat and overlaps the head by one or two millimeters all around. There is a channel or gutter in which the gasket sits. In your photo, the outer part of this channel seems to not be present. How can this occur, except if you have a hugely thick gasket from some other model ?? It's odd.

If there is a gap on the downside and not so much on the upside, I agree with Peter Chisholm.....it may bite you on the bum later.

And without meaning to be pedantic, the spark plug tubes won't have anything to do with it. The cover's relationship with the head at the surface of the gasket is what matters.

I'd like to suggest that you have a good look with a mirror all the way around the gasket and see what is happening where it transitions between being a large gap to a small gap.
 
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