I've had the APS dual port bov for about 6 yrs. during my last boost leak test I noticed it was leaking at the second port (vta port). I took it apart and cleaned the piston and cylinder wall, but it still leaks. I think it maybe from normal wear from the piston on the cylinder wall and lack of lubrication. Has anyone had this problem? If so, how to resolve it? If it needs to be replaced, then which bov to replace it with. Car is an Evo 8 running 26psi, with the MAF, and is used for auto-x and daily driving. So far I came up with Synapse with the softer Milspec spring or Forge RS. Any input is greatly appreciated.

 

You have to adjust the screw/nut at the end. Mine used to leak until I adjusted the screw and put teflon tape on the screw threads.

 

https://www.evolutionm.net/forums/ev...djustment.html

 

Thanks for the reply, I Teflon taped the screw and tightened the screw all the way so it was flush with the nut and it still leaked. Any other suggestions?

 

Did you try backing the screw out and then tightening the lock nut? (going the opposite way you did) Mine used to leak out the vta side and I forgot which way I tightened the screw but it stopped the leak. If that doesnt work then it might be time for a new BOV? I would go check on my car but I am not in the states at the moment

 

Thanks again for the great suggestion. I'm gonna take the bov off the car and make a boost leak tester just for the bov. It will be easier to adjust it off the car and the psi will build much quicker.

 

Just speaking from my experience....teflon tape the adjustment screw AND apply liquid gasket to seal up the cylinder where the rubber o-ring is. I used a bead of Hondabond on the outside of the o-ring. That's what it took to get mine to stop fluttering/leaking. Good luck. I know how frustrating it can be.

 

I've had the APS valve since 68K.

Usually when it leaks under boost test, i pull it apart and re-grease the cylinder the piston rides in. some sort of synthetic grease would work.

Good Luck, and if you decide to sell it, PM me.

 

I'll give the liquid gasket a shot to try to seal things up. how many threads of the adjust screw are showing past the lock nut on your bov? Thank you for the knowledgeable info. I hope this works, I don't want to have to get a different bov.

 

When you re-grease the cylinder wall, do you have any issues with the grease blowing out the 2 ports? Or do apply a very thin layer? Do you grease the internal spring? My spring looks like there's copper anti-seize on it. thanks for the helpful tips, hope it works since i don't want to give up on this bov.

 

Not very many. I think two or three. Takes a bit of trial and error to get it right.....from my experience.