Did a boost leak test..Leaking ISC

[suprafanatic]

I just did a boost leak test yesterday and couldnt believe how many boost leaks i found. I had boost leaking around the first two injector O rings, A leak out the screw on the BOV, a leak from a T bolt clamp, a leak from some Vac. T fittings. Then the biggest we found was coming from the ISC. As soon as we started to compress air into the intake it came right back out the ISC hose. The car would only hold like a pound of boost. So my question is, is the ISC suppose to leak boost back into the intake pipe? or is the diaphram behind my ISC shot? If its not suppose to do this where can i get a new diaphram? or what else could i do for now to fix this leak? I got all the others fix. Thanks

 

[sethron71]

Diaphram and seal ring should stop reverse flow. So no boost should go back through the ISC. How much PSI did you put into it?

Seth

 

[suprafanatic]

well once we blocked off that leak we were able to put like 19 psi in pretty quick.. so where can i get a diaphram?

 

[jdub]

The dealer. It's actually a check valve that prevents reverse flow through the ISCV. It is in a recessed area in the manifold flange under the ISCV.

 

[suprafanatic]

ya i know where its located i took it out and looked at it. I'll see if i can order one from somewhere, could i get a different kind of check valve for now to put in the rubber hose? Like a PVC check valve?

 

[dbsupra90]

no, its a stepper motor. be sure it is put together correctly and that it functions. while you have it apart you would probably be just as well to replace the parts. i dont remember them being very expensive.

http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?Section=FI&P=106

 

[suprafanatic]

Thanks Dave, thats exactly how i have it installed. When i took it out the orange rubber piece looked rather worn and ripped.

 

[Quin]

Other than huge boost leaks, which doesn't surprise me, how is the car liking the new 67mm?

 

[suprafanatic]

pulled extremely hard at 20psi.. not sure how it even hit 20psi with so many boost leaks..lol

 

[TurboStreetCar]

while on the topic is it important for the ISC to have coolant run threw it? for instance will it automatically compensate when cold? Or just for that anti frosting effect like the throttle body?

Im asking unrelated to stock TCCS as im standalone but curious.

 

[jdub]

Same purpose as the TB, to prevent intake icing. It's automatic in the sense that coolant is always flowing through both to prevent it.

 

[max-89supra(t)]

oh shit!!!!!!!!!!!!!!!!

i thought that valve was supposed to be leaking!!!!!!!!!!!!!!!

thanks you slolved my life long supra problem!!!!!!!

my isc valve was leaking like crazy when i tested it!!

 

[BOOSTEDSUPRA]

ditto. would like to know of ways to do the same.

 

[adampecush]

you really cannot "monitor" your pressure as you will always have a leak (open engine valves). The best solution I found was to pressurize the system through the turbo inlet and listen/feel for leaks. Just to be forwarned, the EGR vac modulator will leak (which i beleive it is designed to).

I used a 2.75" to 3" coupling,a clamp, a hockey puck (yes, thats right) through which I threaded a quick-connect air fitting.

 

[TurboStreetCar]

Use your boost gauge to monitor pressure.

 

[BOOSTEDSUPRA]

similar to how i did it sorta. made mine from pvc fittings.

 

[suprafanatic]

well i got the new ISC valve in and the car still drives the exact same.. so im not sure it actualy helped. i need to do another boost leak test to see if its still leaking or not.

 

[dbsupra90]

i thought you reinstalled the injectors and problem went away?

 

[suprafanatic]

The cut out probelm did go away.. im talking about the boost leak i had with the ISC. not sure if the new valve fixed the leak or not.

 

[grimreaper]

solved?