S4s exhaust cam cover gasket leak

[tomcattom]

Not had much time to spend on the car in the past few weeks but I have to move the Esprit out of the garage earlier in the week and while it was sat idling on the driveway I noticed white smoke eminating from the exhaust manifold area as it began to warm up. To my dismay I could see oil dripping on to the manifold from above and burning off but it wasn't clear where it was coming from. I've just been out to the garage now and done a more thorough inspection of the situation and I can clearly see oil coming from the exhaust cam cover gasket at the back of the engine which is then tracking down round the end cap cover onto the carrier and then it tracks forward until it gathers on one of the casting ribs above number 4 cylinder before dripping down on to the exhaust manifold and burning off.

When I resealed the cam towers and adjusted all the shims in the winter I fitted a pair of new cam cover gaskets, dry as per the manual, torquing the cover bolts to 4-6Nm. The surfaces were all thoroughly cleaned before the gaskets were fitted too. I've done some searching and not really turned up much on this topic for the later 4 cylinder cars, unless I'm searching for the wrong thing.

I'm loathed to just tighten the covers up because from experience with other cars that only make matters worse, although in those cases the cam covers are plastic.

Anyone got any advice for curing this leak?

[CarBuff]

Did you refresh/replace the little o-rings under the heads of the cover bolts? I usually leave the old ones on, and fit new ones in addition to the old ones.

Verifying tightness of the cover bolts is wise, worth a double-check.

 

 

 

Helped a friend replace leaky valve cover gaskets just Friday, we replaced both gaskets, but found that one valve cover 'dinged' on its sealing surface as it had apparently been dropped. This created a ridge that ***could*** have prevented proper sealing.👀

 

That said, the most common leak I've seen on the cam carriers has been perished sealant between the cylinder head and the cam carriers, especially on original cars or engines over 60K miles old. Hopefully you didn't brush away the Locktite 518 when you were removing them (repeatedly) to insert valve shims! 🥴😡

[Barrykearley]

The cam towers are sealed on with zero thickness sealant. You should be doing the shimming with no sealant on the tower and sealing on once shimming has been set.

[CarBuff]

11 minutes ago, Barrykearley said:

The cam towers are sealed on with zero thickness sealant. You should be doing the shimming with no sealant on the tower and sealing on once shimming has been set.

X2. ^^^

 

But sometimes the sealant could possibly be inadvertently rubbed aside while wrestling with fitting the cam carriers and the mounting hardware during final assembly.

 

Our cam carriers are now leak-free but I shimmed the valves with the engine OUT.😇

[tomcattom]

All six rubber O-rings were replaced on the cam cover screws; the old items were discarded because they had gone brittle and almost all were snapped when trying to remove them from the bolts. I'll double check the torque on the bolts again tomorrow to be sure its not something as simple as that.

How can the sealant on the cam carriers be rubbed aside during fitting to the head? The cam towers are each fitted over a pair of studs in the head, or are the earlier cars different? Either way in my case I'm 99% sure all the oil is coming from the exhaust cam cover gasket at the back end of the head, I don't have any real worries about the cam tower to head joint, that all looks dry still on mine.

[snowrx]

Given the long perimeter of the cover, the poor clamping ability of the three screws and the annoying consequences of oil on the manifold or in the plug wells, I glue them on. I put the thinnest possible film of Three-bond or grey RTV on both sides of the cam cover gasket and worry about it later when it's time to pry them off.  

[Chillidoggy]

There was no way I could see the cover gaskets sealing if they was dry, three previous failed replacement jobs having proved it. So, I used Permabond A136 on mine, a tiny continuous bead on the carrier, placed gasket in place, same bead on the top, and tightened to spec. No leaks.

I found the cam housing rear cover to be another source of leakage. A new O-ring cured that one.

[tomcattom]

Thanks for the advice all. Sounds like sealant in addition to the gaskets is the way forwards then. Looks like I'll be buying a new pair of cam cover gaskets; I doubt the permabond or any other sealant will adhere to the now oily gasket

Cam shaft rear cap seals were all renewed when the carriers came off so they *should* be okay. Will only be able to tell if they're alright once I cure the leak from above.

[tomcattom]

New gaskets have been fitted today with Permabond A136 either side of each so we'll see if that cures the leak. Only time will tell...