How much boost leak is "too much"?

[Calan]

I know the obvious answer, but seriously...

I have the typical sputtering/misfiring crap at 4.5 - 5K... did a boost leak test at 20psi from my compressor, and all I can hear is the common TB shaft seal leak on the throttle cable side.

If I turn off the air, pressure at my boost gauge drops maybe 5-7psi in about 4 seconds. Constant pressure difference between the compressor and at the boost gauge is maybe 2-3 psi.

My hunch is that this is fairly significant (although not as significant as the UICP coupling that blew off next to my dome piece when I bumped the clamp... but I digress... ).

Would this much of a boost leak cause my crappy performance?

I've read the TB seal replacement threads, but it looks like the seals are hard to find. Anyone have an Ace Hardware, Autozone, etc. o-ring part number that would work?

Thanks as always!

 

[coreyr]

looking for this?

http://www.extremepsi.com/store/customer/product.php?productid=19021&cat=863&page=1

 

[FORMONTOYA]

You should be able to hold test pressure (I test to 25PSI) for about 20-30 seconds without it noticeably falling, then a slow decline over a few minutes down to zero. If you can do that, then you have a properly sealed intake track which will relieve a lot of strain on the turbo.

 

[Calan]

looking for this?

http://www.extremepsi.com/store/customer/product.php?productid=19021&cat=863&page=1

Well, that's not what I was referring to, although I do need to replace my BISS o-ring as well.

Speaking of the BISS, I read somewhere that a standard hardware store #5 o-ring will work. Can anyone verify that?

 

[kenamond]

Well, that's not what I was referring to, although I do need to replace my BISS o-ring as well.

Speaking of the BISS, I read somewhere that a standard hardware store #5 o-ring will work. Can anyone verify that?

The vfaq article on adjusting the BISS lists the o-ring size and the Mitsu part numbers. It's almost at the end of the tech article. I'm not positive if it's #5 (but I think it is), so check it out.

 

[calreef18]

The BISS ring is a #5 at the hardware store. You can get the seals from mach v or order through a shaft seal company, which is what I did, it ended up being a tad cheaper than mach v. If you do a search there's the dimensions of the oil seal, I got chicago rawhide.