The drivers side (LHS from inside car) valve cover on my x308 has historically been difficult to get properly sealed. When I first changed the upper tensioners I ended up having to use RTV to stop the leaking, after about 7 attempts to remove and re-seal!

So, when I went back in 3 months ago and did ALL of the timing gear I took a chance and put the cover back on with no RTV (except in the two required spots). One spot that always smoked was the third bolt on the bottom from the firewall. It smoked again this time so I put RTV on top of the bolt and the smoking stopped. I was pleased that it sealed much easier than the last time.

Current situation: There is a noise under load that was not there before. It is not an overwhelming noise but it "sounds" to me like an air issue. When I inspect the valve cover area after spirited driving I can still smell a little burning oil. The smell seems to come from the area that leaked in the past, but I do NOT see any smoke now...just the smell. The smell does not exist at idle or if the car is driven gently.

I dismissed the valve cover as being related to the sound because my fuel trims are near perfect on the highway and also under load. They also settle out very well during idle, but it can take a couple of minutes. The fuel trims sometimes go very negative when coasting and high positive when idling cold, but I think that may be normal?

Current question: I have another valve cover I picked up from a salvage yard. Other than being filthy it looks pretty solid. Is it worth the trouble to switch the two valve covers (re-using the 3 month old gaskets) and see if that eliminates the sound? Or is it so unlikely, based on what I've explained above, that the valve cover is the problem that it would be a complete waste of time?

 

Greetings harvest14. My humble opinion : sound is not related. But if attempting anyway, I would not re-use gasket (incl. all little 'o' rings around the bolts). Cheers

 

There is no reason for the valve cover to be leaking so you have a problem with your parts. Being the cover or gaskets. My right side cover was leaking until I discovered that there was an hairline crack in the plastic around 1 of the insert for the coils cover.

 

No relation between what you did and the noise

 

The cam cover without cracks and with a good gasket, clean surfaces and new bolt rubbers should never leak. Having to add RTV and other sealants is masking a problem.
You indicate that after a spirited drive you smell burnt oil. I think you have a problem with the full load breather. It is plugged and not working properly. This allows excess crankcase pressure and it is being released thru the cam cover. Since you don't seem to have a problem at idle I don't think you have a problem with the part load breather, but I would clean it anyway.
I would pull the full load breather components and give them a thorough cleaning. Check the breather and hose for any build up or obstructions.

 

+1 to reply #5. About 3 1/2 years ago when I started working on these cars, I had so many problems trying to seal the valve covers. Turns out that the key to keeping these valve covers from leaking are the seals that go under each V/C hold down bolt. There's 14 for each side. I'd get all new seals and make sure you run a small drill bit down the breather also. I'd clean off every last drop of old RTV before putting on all new gaskets.

 

Thanks for the advice all.

When I did the full tensioner upgrade the valve cover seals from a few months earlier when I just did the upper tensioners looked brand new. I still replaced them but felt a little as if it was an unnecessary expense. That's the only reason I was thinking of re-using; in fact I still have the other ones. They looked so good I could not bring myself to throw them away. Generally I agree though, never re-use gaskets. Both gasket sets came with new rubber pieces for the bolts.

I did the drill bit procedure on the part load breather orifice a few months ago. With regard to the full load breather all I did was blow through it. It seemed to offer no resistance so I figured it was OK?