Best oil sealant?

[Rattlenbang]

So after only maybe 4 months since install, the rear half moon seal is leaking. I used a lot of permatek formagasket, but it hasn't held. What have others used that actually maintained the seal over a long time?

[FalcoColumbarius]

I had the same problem when I originally changed the VC gasket. What I discovered is the leak was coming from the cradle the half moon seal sits in because the cradle had not been sufficiently cleaned of the residue left by the previous sealant, thereby creating channels for the oil to leak out of when under pressure. I took a can of brake cleaner and sprayed a little on a clean cotton rag and got right in there and removed the residue. It can be tricky cleaning something that you can't really see clearly but I found that by using my fingers and feeling for residue helped. I'm using Permitex Copper for the sealant this time. I placed a new piece of cardboard under the wagon and she leaked three more drops, I presume from the oil build-up on the block from what had already leaked from my previous attempt. Now there's been nothing for a couple of months. Mission accomplished.

I think that many of those niggling problems issue from an incomplete job ~ like not completely emptying the cooling system of air bubbles that delay the thermostat from opening, hence causing the motor to run hotter. Same with the fuel screw on the IP ~ too much or too little fuel can cause a hotter engine ~ I guess it's all about balance, eh?

Falco.

[Rattlenbang]

Couple of months? Mine lasted that long too, but then started leaking again. Time will tell. I noticed today that oil is seeping out all around the gasket although it's really bad at the back. Neither the new gasket nor the permatex is keeping it in there. I had the same problem with my boat diesel: no amount of new gaskets or sealant could keep the oil inside the valve cover. I'm starting to wonder if the vibration of a diesel engine is the real culprit here, breaking the seal and allowing oil to seep through. The engines I've never had a problem with had the bolts around the circumference of the valve cover; the ones I did had the bolts in the middle. Design problem?

[Growlerbearnz]

The rubber halfmoon is definitely a weak point, rectified by Mitsubishi on later engines by replacing it with an alloy halfmoon. Part numbers are in the archive somewhere.