Leaking Silicone Exhaust Cover Gaskets .. What to do Now?

[Crude Rudy]

1984 911 with a stock 3.2 ~ 150K miles, turbo type exhaust covers.

3 valve adjusts ago I bought the fancy last forever Silicone valve cover gaskets. For the last 30K miles they were as dry as I could hope for. Just finished another valve adjust and they are both leaking/dripping from basically the same spot, on the driver side looking up at the cover - upper right corner down onto the chain cover and passenger side looking up at the cover - upper left corner.

I thought I did not over-tighten them but I put on all new lock nuts so I guess the new nuts may have fooled me. Definitely could feel when they bottomed out. I snugged them all up in a pattern from the inside out then added ~ 1/4 turn using a 1/4 in ratchet.

This is the 2nd time these gaskets have been off and back on the engine during a valve adjust. They looked 100% to me, I just cleaned off the gunk with a bit of purple solvent, made sure the sealing surfaces were clean and smooth and re-installed. They definitely had a cover pattern indented into them but because I put them back on in the same orientation I thought they were fine.

In the area they appear to be leaking I can see on both sides what looks like a slight "crinkle" to the gasket. Am I hosed and need new gaskets or can I simply take the covers off, clean everything again and re-install with less torque on the nut??

Thanks .... Rich

[Quicksilver]

If you can see an issue in a gasket that is leaking then the game is over.

[porterdog]

I'd ensure the covers were still flat (a piece of glass makes a nice surface plate) and hylomar the seals before reassembly.

[Reiver]

You can always try that, nothing to lose but a bit more oil.
I've tried the silicone type in other valve cover applications and had the same result...worked for awhile but after a change or two started leaking.
I've never had issues with the paper type tho.

[Walt Fricke]

I like the silicones, but if you (or at least I) try to pull them off of a hot or warm motor I invariably tear one in at least one place. I suspect they can stretch some when warm, and not return to a uniform thickness, which would account for the crinkle, and perhaps the leak.

I'd be hesitant about using Hylomar or the like, though. As you tighten down the cover bolts you can see these gaskets trying to squeeze out. I think any kind of gasket dressing is going to exacerbate this tendency with this kind of gasket. Bruce Anderson (RIP) cautioned against any gasket dressings anywhere for this reason, though I haven't had trouble with more normal gasket materials, which are a lot stiffer, and also can benefit more from a dressing because they aren't as pliable as the silicone is.

[kodioneill]

The best gaskets to use are the graphite based with the silicone bead on them.

[Flojo]

reinz rules!

[john walker's workshop]

when a car comes in for a service with those damn things, they get them back in a ziplock bag. no way i could guarantee a good seal with something you can't actually tighten up properly.

[kidrock]

some will swear by those silicone gaskets, but not me. I'll never use them again. Just like Kodioneill and JW, I only use the black graphite with the silicone bead. They've never failed me, and they are forgiving on the torque values. A much better product overall.

[sc_rufctr]

John

Assuming you're using OEM gaskets. What torque setting do you use for the nuts?

Peter Z suggested 27 foot pounds from memory. He went into a detailed explanation for using that setting.

[JAR0023]

Originally Posted by sc_rufctr

John

Assuming you're using OEM gaskets. What torque setting do you use for the nuts?

Peter Z suggested 27 foot pounds from memory. He went into a detailed explanation for using that setting.

Pete Z is quoted here with 25 N-m or 18 ft-lbs.

What is the Torque for 911 Valve covers

Count me in with the never agains. Those infernal gaskets are one of my few stupid Porsche purchases. They worked OK up top but the torque window where the gasket and aluminum crush washer both seal on the bottom is way too narrow. Last go 'round I bought the kit from Wrightwood Racing. Traditional gaskets with silicon bead, new crush washers and nylocks. -J

[yelcab1]

No such thing as a life time --- anything.

[tobluforu]

I used them for about 5 years, and they worked great, then they went to hell. No more for me.

[Crude Rudy]

Thanks guys!

Ordered the set with the Si bead on the lower gasket.

Other than this new problem I created, the engine is oil leak free.

I hate oil leaks ......

But the good news was when I started the engine the valves all sound the same, engine run nice and smooth and I used the old fashion method not the backdoor man go, no-go position