allenhah

iTrader: (4)

Hey guys...I still can't seem to control boost on my RX6, and I'm trying to narrow down the possibilities. Is there an easy way to test the wastegate with a vacuum pump? I don't quite understand the internals of a wastegate and would like some pointers. I tried putting vacuum in either of the nipples, but it won't hold any air, so I'm wondering if that's how they're supposed to work. Does anybody have a good reference to a picture or something that shows how the wastegate is set up internally?

Thanks!
Allen

dznutzuk

iTrader: (1)

Sounds like you have a torn diaphram. Think of the top half of a wastegate seperated in 2parts, between the two is a large diaphram. The top side is used for vacuum while the bottom part is the signal line.The vacuum line isn;t always necessary-depending on whether you have an electronic boost controller or not-can't remember how to use a profecb on a single. In the center of the wastegate there is a shaft, now when you apply boost to the side port it will push the diaphram up opening the valve to the gases, vacuum will push it down-closing it. On the top port where you usually the vacuum line when applied willsuck the diaphram upwards again opening the valve to bypass the gases to the exhaust. Bothe ports are seperate from one another divided by the diaphram. So if you apply either boost or vacuum to either side it should hold it if not like you said, if is most likely torn.

allenhah

iTrader: (4)

Thanks nutzuk! That's precisely how I envisioned that it worked.

Aaarghh...so after putting my single turbo kit together, it looks like both the BOV and the wastegate have torn diaphragms. I guess that's the risk with used kits.

I guess I'm in the market for an HKS wastegate now. Anybody got one they're trying to get rid of? Anybody interested in an Apex wastegate that's possibly rebuildable?

manatecu

iTrader: (6)

You can buy a diaphram for the HKS, its cheaper and easier than trying to fit a new one.


This may help:
http://www.autosoftsys.com/supra/wgfix/


Find the component numbers here:
http://www.hksusa.com/categories/?id=1096

Search on Yahoo for the model numbers. Horsepowerfreaks has alot of this stuff.

Chris

jreynish

iTrader: (2)

yup you can replace just the diaphram usually run from 125-200 depending on the WG fairly easy to replace.
Not sure about BOV's but I think you can rbuild those do

allenhah

iTrader: (4)

Anybody know where I might get a diaphragm for the Apex wastegate? From my understanding, the Apex units seem to be pretty unreliable anyway, so instead of going down that route, I decided to just buy a 44m Tial wastegate with v-band flanges and have it all welded in. I also got a Tial BOV while I was at it to replace the Greddy unit...gonna be getting welding done anyway, so might as well do it right.

jreynish

iTrader: (2)

Greddy WG's don't have any kind of reputation for being shitty? if your WG is Greddy or Trust I would spend the 140 USD and replace it.

allenhah

iTrader: (4)

true...but i was able to get the Tial for just a little more, so I figured that was the way to go...

TrentO

One key thing to remember is it will take a lot more than 7 psi to open a wastegate with a 7 psi spring in it. The spring has to hold against the exhaust pulses and the 7 psi in order to function properly.

-Trent

jreynish

iTrader: (2)

no it takes very little extra the exhaust pressure against the piston for the WG is minimal, I tested my wastegate by Regulating my compressor Regulator to 15psi and then hooked the end of a vacume tube to the nozzell of the compressor gun, and the wastagate nipple opened the Compressor nozzle and it works just fine. that is how I tested mine good way to test your own. My WG spring is a 14.7 PSI spring and it took 15psi to upen it fully so that is not significantly more IMHO.

allenhah

iTrader: (4)

Wait wait...I'm a little confused on your technique here. Isn't the bottom line this:

I should be able to hook up a vacuum pump to the top nipple of the wastegate (or pressure pump to the side nipple) and be able to pull and hold some vacuum such that it will hold the wastegate spring pressure? i.e. if I have a 10psi spring in the wastegate, I should more or less be able to pull and hold 10psi of vacuum in the top nipple?

Basically I can't hold any vacuum in the top nipple, which seems to imply to me that the diaphragm is torn.

jreynish

iTrader: (2)

ok, your External wastegate is not actuated with vacume is is actuated by boost, the nipple on the side of the WG is feed by boost the top one should be open vented to the atmosphere unless you have a boost controller then it hooks up to this nipple. see the picture below,
The Red Circle should be hooked up to a Boost source and test as I indicated above, now the one circled in blue should be hooked up to you boost controller if you have if not then dont' hook it up.
Hope this clears things up.

tkuwaha

iTrader: (18)

I rebuilt my Apexi wastegate with an HKS racing wastegate(50mm) diagphram from www.horsepowerfreak.com. Hole pattern is different between Apex'i and HKS, but you can use a hole puncher or something to create new holes. A replacement diaphram from Apex'i USA was twice the cost and was a special order item from Japan.
I recommend you open up the wastegate to see if the diaphragm is really torn(Sounds like it is from your description, though). Make sure you clamp down the top housing or put your weight on it when loosening the six screws!! Top nipple should hold vacuum, but the bottom nipple wouldn't even because of some bleed-through around the valve stem. You'll see what I mean when you take it apart. Also, if your wastegate is the non-water cooled version and have a

tkuwaha

iTrader: (18)

continued from above post...
...bronze colored guide around the valve stem, you might want to get it honed(open up the inside diameter) to prevent it from sticking under hard use. Search the forum for details on this.

allenhah

iTrader: (4)

Thanks for all the tips guys! I'm planning on opening up the wastegate when I get the parts back from the welder...I'm definitely curious to see what I find as well. Yeah I learned about the possibilities of the Apex units sticking, which is why I decided to just replace it completely with a Tial 44mm unit. I'm interested to see what you mean by the bottom nipple not holding vacuum/boost...

Thanks again!

allenhah

iTrader: (4)

As suspected, the diaphragm was totally torn:



I reinstalled everything last night with the Tial wastegate, and everything seems to be working great for now!

maxcooper

That's great Allen. I'm glad you found the cause and were able to fix it (well, replace the wastegate). It is interesting to see the torn diaphragm. Any idea what caused the failure?

-Max

allenhah

iTrader: (4)

No idea...prolly just worn out, I guess? I bought it from Fritz off his track car, so I think the heat prolly killed it?

Dunno...is it pretty uncommon for this to occur? It seems like all wastegates use the same basic design, and having a rubber diaphragm would be torn eventually given the heat and fairly abusive conditions...

jreynish

iTrader: (2)

No it is not uncommon, wastegate diaphrams are just as suseptable to failure as any other thing related to extreme heat. Greddy told me that the diaphrams usually last 80,000km's on street driven cars.

allenhah

iTrader: (4)

Speaking of...any idea where I can source replacement diaphragms for my busted Greddy Type R and the Apex wastegate?