Boost leaking out valve cover

[Hiitman]

So I had some good 23-24psi pulls. Then out of no where it won't go above 21. Then 18 and now it won't go above 16. It's probably something very simple but when I did a boost leak test there was air leaking out my catch can and when I popped off the filler cap I could hear bubbling. Compression is 190 on all four and boost leak test got to 30psi on a 5gal compressor until the plastic connection replacing my boost controller shattered. Could it just be that my boost controller died? Nothing fancy, just a forge unos mbc.

 

[Mr Peepers]

I would first look at the MBC, it could be backing itself out.

An excessive amount of air coming from the crankcase/valve cover can be caused by a leaking PCV valve(if you have one). A little air leaking out is normal though; still unlikely that that much air is leaking out and not allowing you to hold boost.

 

[Hiitman]

I figured it would be something simple like the mbc since my wastegate spring is set at 15psi. My pcv valve is running to a catch can. I'll see if I can borrow a mbc and test that out.

 

[Hiitman]

Turned the boost controller all the way down and nothing changed. Any suggestions on an effective exhaust leak tester?

 

[Hiitman]

Doesn't look to be any exhaust leaks. I drove down to Jacks Transmissions and they suggested capping the vac line from the compressor housing to test if the boost control has gone bad. They said a 15psi spring in the wg will open at about 25 from the exhaust pressure. Also, there's oil residue around the vac line where it connects to the nipple on the compressor housing and I saw slight smoke coming from underneath the turbo. Could the seals be going out and it's leaking pressure into the oil return?

 

[Hiitman]

Yup. Bad boost controller. I capped the line off, feathered it to about 23psi and let off. Jacks said that the leak is from high oil pressure and that the inlet for the oil return to the pan is causing slight flow issues.