BOV doesn't seem right.

[CelicaKidd_205]

On my 1994 Celica GT-Four my OEM dump valve split @ the vacuum chamber a while back, so I jerry rigged a used Greddy type RS BOV in there to make it work. It had been working fine for a while, but lately I've noticed I'm getting a bit of surge when I let off the gas @ lower RPMs or if I feather off the gas. At first I was thinking I may have a vacuum leak causing a weak pull on the plunger, however I don't have any idle problems and I can't hear any leaking (trying to hear over a cone filter mind you). I'm thinking perhaps the plunger may be sticking a bit to the point that when the RPMs are lower and the vacuum draw is less, the vacuum in the chamber is not enough to overcome the stickiness.

Does this make sense to anyone? If so, what should I use to clean stuff when I disassemble the BOV? Brake cleaner? Throttle cleaner? Other? Is there any kind of lube I should put on something to prevent it from sticking?

Any input is appreciated!

[Skym]

Leak on vacuum side can affect BOV. Also the valve can get oil deposits around it (what you already mentioned) when turbo has failed. Cleaning the valve might make a difference. Also intake airleaks can affect BOV.

[CelicaKidd_205]

Well, I checked it over thoroughly. No leaks in the vacuum hoses. So I took apart the vacuum chamber of the BOV, right away I noticed the centering plate for the spring adjuster was out of place, and the spring was in between it and the chamber wall. So I corrected that, but the problem still existed. I took it apart again and disassembled the diaphragm. I noticed there is a crack in the diaphragm right where there is a plate that holds it together. It's small and there is still some fibre material holding it together, but I'm pretty sure that's the issue.

I've got some high grade silicone that I use at work for making gaskets, so I've coated the area with that and am waiting for it to set ATM. Looks like I will need a new BOV soon :P

[CelicaKidd_205]

Great! Now the plunger won't hold boost pressure. The valve blows off now, just I'm lucky to get 3-4psi. Anyway I ordered a new Greddy Type RZ valve off Ebay... made sure it was legit and not a copy first though :P

[Skym]

I bought a piston type Synchronic BOV, no more diaphram. Also reacts faster.