Boost leak

[gsxeclipse97]

Well i was working on the car yesterday and when i turned it on i noticed a hissing sound. Kind of like when you suck air through a straw. I couldn't make a pin pointed area but im going to assume it was coming from the tb area because when i put my ear closer to it it seemed to be louder there. If that is the case do i just need to replace the gasket that is there to fix it? I have a 2g tb elbow with a 60mm tb.

 

[absolute_DSM]

Dont rule out shaft seals. Try the spray and bubble method to pinpoint.

 

[gsxeclipse97]

I wouldn't think its the seals because those are new. but then again the head gasket was new and it leaks massive amounts of oil. I was checking to see if i could feel if air was coming in somewhere but i didn't feel anything but its very loud hissing just at idle i can hear it clearly standing in front of the car

 

[DSMunknown]

Use soapy water.

No one else can find your boost leaks without being right there beside you. All we can do is give suggestions on where to look. So here are my initial thoughts on where to look:

• Throttle body seals (there are two of them)
• BISS screw
• PCV valve

If it's the BISS screw, just put some Permatex Ultra Black RTV Silicone Sealant in the hole and wait for it to cure. If it's the seals, just replace them and put some RTV on them to prevent air leaks. If it's the PCV valve, just reroute it to the catch can (you do have one of those, don't you?). Actually, do this anyways. Don't forget to cap off the PCV nipple on the intake manifold with a rubber vacuum end cap.

You should also take some time to make one of these. You will love it. Boost leak test for the win.

 

[romeen]

If it's the seals, just replace them and put some RTV on them to prevent air leaks. If it's the PCV valve, just reroute it to the catch can (you do have one of those, don't you?). Actually, do this anyways. Don't forget to cap off the PCV nipple on the intake manifold with a rubber cap.

Anthony, unless I am misunderstanding, you wouldn't want to place any RTV on the shaft seals. This could cause binding of the shaft resulting in improper function of the throttle plate (potentially dangerous). It's actually recommended to grease them with dielectric grease to help ensure smooth opening/closing of the throttle plate.

It's also not a good idea to disable the PCV system (again, I apologize if I am misunderstanding you ). But if he caps the nipple on the IM for the PCV system then what is providing vacuum to the PCV?

To the OP, if you can actually hear hissing during idle then the leak is most likely fairly substantial. Check all your vacuum hoses to make sure none have become disconnected. Pay particular attention to the hoses going to the EGR valve.

Ultimately, there is no substitute for a proper boost leak test. Make a tester following one of the methods in the tech section and pressurize your intake and check for leaks. This is ALWAYS a good idea.

 

[DSMunknown]

Anthony, unless I am misunderstanding, you wouldn't want to place any RTV on the shaft seals. This could cause binding of the shaft resulting in improper function of the throttle plate (potentially dangerous). It's actually recommended to grease them with dielectric grease to help ensure smooth opening/closing of the throttle plate.

I always have sealed this gasket and this gasket with RTV. I've never had any problems, but I will look into this. My guess is that you're probably right. Good to know.

It's also not a good idea to disable the PCV system (again, I apologize if I am misunderstanding you ). But if he caps the nipple on the IM for the PCV system then what is providing vacuum to the PCV?

Actually, I believe it's a great idea (and I'm certainly not alone). The PCV is supposed to act like a one-way check valve. Unfortunately, they rarely do their jobs (i.e. open and close properly), even brand spankin' new ones. Thus, this valve is notorious for sticking open because of all the gunk and grime that finds its way through the valve. Thus, you have a large boost leak. Read more here.

 

[timot]

If this is happening at idle soapy water isn't what you should do, since it is a vacuum leak. correct me if I'm wrong, but the soapy water would be ingested during idle, during a vacuum condition(<0psi). If you want to find the overall location use propane gas and listen for your idle to change rpm's. That will narrow your search, then do a leak test.

 

[DSMunknown]

If this is happening at idle soapy water isn't what you should do, since it is a vacuum leak. correct me if I'm wrong, but the soapy water would be ingested during idle, during a vacuum condition(<0psi). If you want to find the overall location use propane gas and listen for your idle to change rpm's. That will narrow your search, then do a leak test.

You do a boost leak test in conjunction with soapy water. This way, when you pressurize the system, air will come out. When this happens, and the soapy water is applied to an area where there is a leak, lots of bubbles will form, which will be very noticable to the naked eye.

 

[romeen]

I always have sealed this gasket and this gasket with RTV. I've never had any problems, but I will look into this. My guess is that you're probably right. Good to know.

Actually, I believe it's a great idea (and I'm certainly not alone). The PCV is supposed to act like a one-way check valve. Unfortunately, they rarely do their jobs (i.e. open and close properly), even brand spankin' new ones. Thus, this valve is notorious for sticking open because of all the gunk and grime that finds its way through the valve. Thus, you have a large boost leak. Read more here.

OK, there was a misunderstanding. Since you mentioned "seals" and the fact that your post followed two previous posts that were talking about shaft seals I assumed that's what you were referring to as well. But I see that you meant the TB elbow-TB and TB-IM gaskets. Although not called for by Mitsubishi I have also used RTV here with good results (although I had sort of a unique situation but I won't go off on that tangent).

I completely agree with you that our PCV valves typically do not function as intended. But I feel the catch can/inline check valve method makes the most sense although I realize that this is still a commonly debated topic. I don't want to veer too far from the OP's original concern here but this frequently referenced thread discusses the pro-PCV view and it's shortcomings and an easy fix:

http://www.dsmtuners.com/forums/showthread.php?t=229338&highlight=stupid+pcv

 

[DSMunknown]

^^ I beat you to it in post #4.

 

[romeen]

^^ I beat you to it in post #4.

Crap, I should've known.

 

[DSMunknown]

^ Too slow, old man!

 

[timot]

ah in conjunction with the boost leak test..noted

 

[oldman]

Actually, I believe it's a great idea (and I'm certainly not alone). The PCV is supposed to act like a one-way check valve. Unfortunately, they rarely do their jobs (i.e. open and close properly), even brand spankin' new ones. Thus, this valve is notorious for sticking open because of all the gunk and grime that finds its way through the valve. Thus, you have a large boost leak. Read more here.

Actually disabling your PCV valve is a terrible idea, read Jim's thread in your #4 post. Sure the PCV valve is known to leak and the solution is an inlined check valve, you certainly don't want to fix a problem by creating another.

 

[gsxeclipse97]

No i don't have a catch can but i'll pick one of those up on friday. the weird thing is tha the people who put my 6-bolt in when it ran said that that hose didn't need to be connected to anything becaues it just put oil pack into the intake like it says. I have noticed that air comes out of it but didn't think anything of it cause they said that would happen.. I have heard that its a bad thing to not have a pcv so im not sure if i want to mess with that. but a fuel filter i guess i just need to find one like that and re connect that hose.

 

[DSMunknown]

Actually disabling your PCV valve is a terrible idea, read Jim's thread in your #4 post. Sure the PCV valve is known to leak and the solution is an inlined check valve, you certainly don't want to fix a problem by creating another.

The only reason I recommended doing so was because I like(d) it as a "quick fix" for a notorious boost leak. I forgot the PCV valve could be easily cleaned out and used again. After I followed my own misguided advice, my catch can was filling up rapidly with a mixture of water, oil, and a bit of fuel. I wouldn't be surprised if my intake system was sucking all that crap in. Now I've got the correct setup. I'm sure I'll be much happier.

I think Ludachris should fix the link in the Tuning Guide. (I can't post up the link because the Tuning Guide is currenlty down. However, it's one of the categories under "Free Mods" (or is it "Free Power"?) that discusses the PCV valve and re-routing it back into the intake system.) Anyways, it gives an old link to kpt4321's tech page. Unless one of the Wisemen decide to do a write-up on the PCV system in its entirety, then the link should be changed to Jim's thread. Just a thought.

 

[oldman]

I'm glade you're decided to do it right. I tried clicking on the "for example" link under the "free mod" and it doesn't open anything nor linked to the said article, do you have a direct link to that article? I can fix it rather quickly by adding to the article along with the link to Jim's thread. This would be much easier than trying to convince those old people (Luda/kpt4321) that why the old "Taboo way" is the wrong way.

 

[DSMunknown]

Right now I'm dancing 'cause the Sox are going to the World Series. Don't bother me now.

You have to use the trusty ol' Wayback Machine. Here is the link, but it's broken. Here it is fixed with the Machine.

 

[oldman]

Right now I'm dancing 'cause the Sox are going to the World Series. Don't bother me now.

You have to use the trusty ol' Wayback Machine. Here is the link, but it's broken. Here it is fixed with the Machine.

Congrats on the Red Sox win......stupid Yankees

If the link is broken, let it be broken, I thought it was one of our in house tech articles. I will pm Chris about changing that part in the "Free Mod" section.

 

[DSMunknown]

If the link is broken, let it be broken, I thought it was one of our in house tech articles. I will pm Chris about changing that part in the "Free Mod" section.

It's been broken for years. I've also posted a little somethin' somethin' here for Chris.

Holy shat, did we finally get rid of Kyle's Tech artile telling newbies to tap into their BOV lines for an MBC boost source? A round of applause is in order (took you guys long enough ). (Don't worry Kyle, I still love ya. )

BTW, I think we should doing something (aka delete/respond to) such misinforming Tech Guides as this one. The Tech Guide area does need some work. I think it's been neglected for a long while. IMHO, of course.

 

[oldman]

Holy shat, did we finally get rid of Kyle's Tech artile telling newbies to tap into their BOV lines for an MBC boost source? A round of applause is in order (took you guys long enough ). (Don't worry Kyle, I still love ya. )

I deleted it.

BTW, I think we should doing something (aka delete/respond to) such misinforming Tech Guides as this one. The Tech Guide area does need some work. I think it's been neglected for a long while. IMHO, of course.

I will take a closer look tomorrow.