Valve Cover won’t seal
 

Hi all!

I’ve got a 94’ with a FM turbo kit and I hadn’t been driving it because of issues I’de been dealing with with excessive blow by causing oil leaks. I understand my rings are probably the underlying issue and I should rebuild the engine etc. but my daily blew up so now I’m forced to drive the leaky Miata. I’ve never taken apart an engine down to the pistons before and I’de imagine it take me a week to get through at least which simply isn’t an option with my schedule so fix the leak it is!

I know blowby is the problem but I just need this oil leak to stop. I’ve replaced the valve cover gasket many time, CAS o-ring, used the black oil resistant permitex at all the places i’m supposed to. But i’m running out of ideas. I might be over tightening the valve cover bolts as I always torque them to the higher end of the recommend range. My logic is more tight, less oil, but my logic doesn’t extend far into the automotive world lol. I also might have scored the surface while trying to remove old permatex. So i’m just looking for ideas to make this bitch seal. It definitely doesn’t have to be pretty. If I have to put goo around the whole valve cover I will.

It leaks predominantly from the back of the valve cover near the coil pack and at the edges of the CAS (where there is plenty of permatex max oil resistant whatever).

My plan at this point is to, buy a new gasket (again), clean the shit out of every pairing surface (again), and try to smooth out some marks I may have left in my hacking, then don’t over tighten in.

Any other ideas would be awesome, the oil leak is pretty bad, can’t ignore it anymore.

Thanks a ton,

AJ

What kind of gasket are you using? I have always heard the foolproof way to get it to seal up is to use an OEM gasket. If you're considering blowby as the root cause though, I don't know if even that will seal. You might consider doing the 'tiny hole mod' on the valve cover so it can breathe and alleviate the blowby better. I think that's your first step. Have you ran any compression/leakdown tests to see overall engine health?

This sounds dumb, but is your valve cover gasket seating all the way?
When i painted my valve cover the first time i didnt take the coil pack off and the gasket got rolled over and pinched right there, causing a pretty messy leak.

I get my gaskets from Moss Miata, whichever one they sell. I haven’t ran either test but I have a catch can filling with oil and crank case pressure causing the leak so I just assume the rings are bad. It’s a freshly built engine, only has 5k miles on it or so, but the guy that built it must’ve done it wrong, or I muffed the break in, either way i have to drive it as it is now so we’re here. I’ll look into the “tiny hole” mod, thank you!

Im positive it’s seated properly i take everything off and go around it with a flashlight to make sure it’s all laying flat.

Do you have both valve cover ports going to a vented catch can? Do that, and when you do the gasket follow the tightening sequence closely or else it will leak. If you run both ports to a catch can that should alleviate some of the crank pressure.

Sorry, I should have included my ventilation set up. I have the PCV vent going to a catch can then to the intake manifold. (PCV is good, ive got the upgraded one as it does not leak). and i have the other side vented to another catch can going pre turbo in hopes it’ll apply some sort of suction.

I would get rid of the pcv alltogether and vent both ports to one vented can.

Yes.

Just to piggyback off the OP here, anyone know off the top of their head the fitting sizes that fit with some loving into the valve cover to adapt to 3/8th line? Specifically the one on the intake side where the PCV was, that port is rather large. I'm trying to put 90°'s on both sides to mount a VTA catchcan by the fuse block.

Moss sells both Mazda and aftermarket VCGs. Which one did you get?

I run a Felpro with great success. Just FYI

I tapped the PCV side for 1/2 NPT. If you pull the fitting out of the hotside you can drill the hole for something larger than stock if you want.