Valve cover gasket leaks/weeps

[digger]

So I've had this long term issue where the valve cover leaks and weeps, nothing i can think of fixes the issue. i've used new gaskets (both types) with and without sealer, new D plugs and nothing seems to work. i always clean surfaces meticulously. i havent checked to see if the cover is warped but i have a spare here that is good

So i've concluded that under high rpm load the blow by is pressuring the crankcase and valve cover. My crank case vent on the VC goes to a catch can has a small filter venting to atmosphere.
i have a blow by meter im going to hook up to measure how many CFM it is.

has anyone seen rubber gaskets ? im thinking that this might off a better more forgiving seal. it wouldn't be hard to make one

[modernist]

Warped valve cover?

[digger]

Warped valve cover?

if it is its not obvious

[jeffnhiscars]

Isn't the breather supposed to keep pressure under the BC at 1 bar ?

Id lay the cover on a thick glass plate to check for flatness

[digger]

normally the breather hose connects slightly upstream of the throttle body and sees at best very slight vacuum (whatever is created due to restriction of airfilter/afm etc) but for the most part its at close to atmospheric pressure. if there is too much gas trying to escape due to blow by or possibly crank/piston pumping action then i'm theorizing the crank case and VC pressures can rise a little bit causing weeping.

i'm going to recondition/clean the spare VC i have as that's the original one is used initially and it is not warped

[tinkerputzer]

I've chased VC leaks for what seemed like forever on 2 different e30s. Like you i exhausted all options. I even had a VC itself surfaced but that just makes it more thin and more susceptible to warpage. I eventually came to the conclusion that a more forgiving gasket is needed. Something thicker and rubbery like the 24v engines have. I contacted felpro to see if they would ever make a permadryplus for m20's but the answer was no. I took matters into my own hands and made my own VCG out of high temp silicon sheet. Bone dry now. Before the silicon gasket i would try something new and wait and see. I'd always check the exposed upper surface of the block as viewed from the exhaust side and after a few days it would always collect oil residue. Guess what, now that it doesn't have that oil residue anymore it has slight bit of surface rust :)

[digger]

I've chased VC leaks for what seemed like forever on 2 different e30s. Like you i exhausted all options. I even had a VC itself surfaced but that just makes it more thin and more susceptible to warpage. I eventually came to the conclusion that a more forgiving gasket is needed. Something thicker and rubbery like the 24v engines have. I contacted felpro to see if they would ever make a permadryplus for m20's but the answer was no. I took matters into my own hands and made my own VCG out of high temp silicon sheet. Bone dry now. Before the silicon gasket i would try something new and wait and see. I'd always check the exposed upper surface of the block as viewed from the exhaust side and after a few days it would always collect oil residue. Guess what, now that it doesn't have that oil residue anymore it has slight bit of surface rust :)

i too believe that something that compresses a little bit under preload is going to conform better. how thick a gasket did you use? i thought about silicone but its apparently not great with oil long term but its hardly submerged....still i was thinking about rubber. viton is the best rubber resistant to fuels and oils, heat etc but its very expensive ridiculously expensive infact, maybe neoprene or nitrile is ok . im going to look around for generic gasket rubber that you use to cut your own shape etc

[tinkerputzer]

I'll track down my order in the am and let you know. Here's a pic i dug up.

[jeffnhiscars]

It's been so long since I've seen that rubber gasket material that i forgot I used to have a supply of it. It's one of those things you have for years until you lose it, but great stuff.

Neoprene if memory serves me and if you go slow with a very sharp blade I believe it's fairly easy to cut a clean cut..

Did you trace the outside then freehand the inside ?

[tinkerputzer]

I tracked down my order and material thickness was 1/8". The ebay seller was adrian22305. I'd provide a direct link to the auction but it's no longer available. Here's his store link though.

Did you trace the outside then freehand the inside ?

Yes exactly. I traced out an old VCG then processed out the silicon with an xacto knife, hole punch, and cutting wheel. When cutting out the silicon use the hole punch to put holes at as many of the transitions as you can. Then use the xacto knife to cut from hole to hole. Easier than trying to cut all those transitions with an xacto knife. Be sure to make it a bit wider than the old gasket and that it is clean and free of oil residue when installing to get a good clamp up on the gasket with out it squeezing it out since it doesn't have a rigid sheet of metal through it like a standard VCG.

Digger, i'll concede silicon may not be the best material but i've had my VC off a few times, reused the now flexible gasket mind you :), and it seems to be holding up well enough. I can't see any signs of degradation.

Was thinking how nice it would be if someone were to make a VCG of a rubbery material and have the rocker plugs and gasket molded as one. Fuck that would be nice.

[digger]

i got some some 3mm nitrile rubber as that seems to be the most economical rubber tha good upto 110C and has great oil and fuel resistance. going to price up getting it laser/water jet cut otherwise scapel it myself and use a punch for the bolt holes.

glad the silicone worked out ok.

[ForcedFirebird]

Lay your cover on the head and check of the rocker shaft lock is hitting it and keeping it up a little. I've had a couple that touched the cover and would warp it when bolted down, and also have just had warped covers. People always complain of m20's being leaky, but we have been pretty successful at keeping them dry.

I rub a small amount of The Right Stuff on the VC gaskets and let them dry before installing just as a safety net if you will.

[jeffnhiscars]

^ the voice of experience

[5Toes]

the Elring brand gasket is more rubbery and is pretty thick, maybe 3mil at the most. Its very different from the VR style.

have you tried using threebond or similar on the valve cover to form the gasket? Ive had great luck sealing timing covers, oil pans, etc. with threebond 1184/1194 (1184 has no lead or vice versa.. I cant remember). the shit rocks and is super eays to remove because eit is synthetic rubber based. also known as yamabond and Hondabond. Hondabond (the thicker stuff) is actually threebond 1211

[digger]

ive used flexible RTV with the OEM gasket recently and seals for a bit but longer term it weeps again. ill look into the Elring.

it could be the cover on there is warped im prepping an old cover to swap out