Bov or Wastegate? Please Help!

[obsolete]

So, all of a sudden driving yesterday, i was not able to build boost. It drives perfectly fine with no hesitation or stumble. just does not get the boost and power. I have a greddy RS and when i would rev it at idle, it would usually let off with compressor surge sound, but now all it does is give me a squeal like air leaking. i tried loosening and tightening all the way and no surge or letting off sound. my idle is fine minus a tiny bog/stutter every so often. My question is what are the symptoms of bad BOV? Do you think it's busted or my WG is stuck open? How do i check if the wg is functioning correctly?

[zenki.life]

yea my only gues(since im not a licensed mechanic lol) is that you have a leak somewhere. it would explain why you dont boost.

[vortxxe]

The chances of your wastegate being stuck open are pretty slim, it doesnt happen too often.

Most likely culprit is a boost leak. Check all your couplings (check if they are secure, and also inspect them for cracks or holes)... and then double check them to be sure.

To check your BOV, put your hand infront of it and rev your engine up aggressively (to build a bit of boost). The BOV should not allow any air to escape until you let off the throttle, at which point it should open and let out some air.

[Sileighty_85]

its not your BOV

if the BOV was opening underboost the engine will hit a brick wall
because it relaseing all the metered air

if you have an exhaust leak at the turbo will will cause this, or if the turbo is blown

[drifter_for_life06]

^^^^wat he said. I have similar problem but i KNOW FOR A FACT its an exhaust leak at the manifold->turbo gasket. I can hear the exhaust leak loud as shit thats how I know.

[obsolete]

say the turbo is blown, but BOV is ok, shouldn't the BOV still do it's function at idle? like build and release air?

[jackal264]

the bov would never open b/c there is no pressure to release b/c the turbo is not making any boost. a blown turbo would be really easy to spot though. you would have a lot of smoke comming out of the exhaust. however i have seen a wastgate get stuck open and that would cause similar issues.

[pinkarrowsnow]

Torn coupler probably look at all of them. If you have a boost gauge whats your vac now and what was it before. Maybe a vac line popped off the wastegate. Give more info def sounds like a vac leak.

[obsolete]

come to think of it, i do have a lot of noise when I start to get going. whining and metal rubbing. I thought it might be noise from the trans. I'll have to check that later. I didn't notice any smoke coming out the exhaust. would it be at idle or while driving? or all the time? It just happened after I set the timing. I didn't touch anything else. I have an electronic gauge that doesn't read vac. wack.

[Sileighty_85]

Torn coupler probably look at all of them. If you have a boost gauge whats your vac now and what was it before. Maybe a vac line popped off the wastegate. Give more info def sounds like a vac leak.

Torn couple would would have the same symptoms as if the BOV was leaking.
If the Vac line popped off the W/G it would over boost

If your hearing a Grinding noise durring boost then the Compressor wheel is making contact on the Turbo housing.

Pull off the turbos intake pipe and check for shaft play on the compressor wheel

it it possible for the bearings to wear out and and not leak oil

[pinkarrowsnow]

Torn couple would would have the same symptoms as if the BOV was leaking.
If the Vac line popped off the W/G it would over boost

If your hearing a Grinding noise durring boost then the Compressor wheel is making contact on the Turbo housing.

Pull off the turbos intake pipe and check for shaft play on the compressor wheel

it it possible for the bearings to wear out and and not leak oil

Yeah what am I saying about the wastegate line popping off it happened to me haha i hit like 40psi duh i didnt think straight.

[smelly240]

IF HIS GREDDY RS WAS LEAKING AND RECIRCED - ITS NOT GONNA MAKE BOOST *OR* DRIVE LIKE A TORN COUPLER...

IVE SEEN THE TURBINE WHEEL BREAK OFF A T25 MORE THAN ONCE (TWICE ACTUALLY :p )

IF IT DOESNT GO NUTTY RICH - A COUPLER ISNT TORN

no clue why thats all caps - but im not retyping it.

[obsolete]

Well i did some more searching and it sounds like the gasket from manifold to turbo is a high possibility. gonna check that as well as the bov for leaks. my Greddy is not recirc-ed. fix one thing and something else goes wrong. this is aggravating

[opponheimer]

If its not building boost your wastegate actuator must have popped off the flapper arm. That is the only way it would run right and not build boost and the turbo not being blown... There is your solution.

Use safety wire to attach the thing.


Other than that you've given no info on motor, turbo setup, whatever... a motor with a bad turbo inlet gasket would still be able to build some boost and you'd hear it/feel it on a cold motor if you put your hand around the flange..

[obsolete]

If its not building boost your wastegate actuator must have popped off the flapper arm. That is the only way it would run right and not build boost and the turbo not being blown... There is your solution.

Use safety wire to attach the thing.


Other than that you've given no info on motor, turbo setup, whatever... a motor with a bad turbo inlet gasket would still be able to build some boost and you'd hear it/feel it on a cold motor if you put your hand around the flange..


That is exactly correct! I just got home and took a look. Stupid me. :duh:

http://i691.photobucket.com/albums/vv277/Choematic/wastegate.jpg

How do I keep that attached? what is a safety wire?

Thanks all for your quick responses. learned a lot.

[opponheimer]

go to home depot, its in the sign section... its wire you just loop in through the hole on the flapperthen wrap it around the actuator rod and then twist it off, get creative.. itll hold.

or you can just get a new c-clip if u can find one that fits

[Ceepo]

Weld it closed :)

[opponheimer]

Weld it closed :)


lol.. he won't have trouble building boost then