I never removed the pipe from the turbo bell to the P/S valve cover. The car has only 26k miles, wanted to keep it stock looking. Anway, blm was 140 so I went looking for the leak with my newly built boost leak detector. I was pumping in air to the turbo from my compressor. Here is what I found: When I removed the pipe from the valve cover and held my hand over the opening of the pipe, I had no leak of air and compressor showed 20 psi. When I put the pipe back in the valve cover, I had a huge air leak and the compressor didn't even show pressure. Does this make sense? I know the valve cover isn't expected to make an air tight seal, since we put little K and N air filters in them. I'll remove the intercooler tomorrow and give it it's spring cleaning, then reinstall it and continue looking for leaks. Thanks.
Vacuum leak from pipe to valve cover
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Black Power
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So you were holding your hand over the opening that goes back into the bell, not the hole in the valve cover, right?
I held my hand over the pipe that connects to the hole in the bell housing. So, yes, I think we are in agreement.
Black Power
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Ok..just checking. :wink:
So when the pipe is installed back in the housing, and you (try to) pressurize the motor, the air is leaking out around that pipe? It seems like if it's bad enough to keep the compressor from showing pressure, that would be a horrible running car! Vac leak city for sure, but it would take a pretty big leak to send your blms up that much.
I understand wanting to keep it stock looking, but I would remove that thing and put it back on if you were at a car show or something
and just use the breather and blockoff that most people with stock turbos use.Ok..just checking. :wink:
So when the pipe is installed back in the housing, and you (try to) pressurize the motor, the air is leaking out around that pipe? It seems like if it's bad enough to keep the compressor from showing pressure, that would be a horrible running car! Vac leak city for sure, but it would take a pretty big leak to send your blms up that much.
I understand wanting to keep it stock looking, but I would remove that thing and put it back on if you were at a car show or something
That's the funny thing about it....when I put the pipe back into the valve cover, I get no obvious air leak. Car was running fine, although it doesn't idle worth a damn. I figured that was due to the factory chip....see, I told you the car was stock! I sprayed soapy water on the pipe, valve cover, everywhere...no bubbles! I can't even feel any air leaking from around the valve cover or from around the pipe. As for blm=140, hey that's nothing! My other GN was reading 150! So far I found the seal on the throttle body leaking, behind the TPS sensor, but that's in another post.
Black Power
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That's the funny thing about it....when I put the pipe back into the valve cover, I get no obvious air leak. Car was running fine, although it doesn't idle worth a damn. I figured that was due to the factory chip....see, I told you the car was stock! I sprayed soapy water on the pipe, valve cover, everywhere...no bubbles! I can't even feel any air leaking from around the valve cover or from around the pipe. As for blm=140, hey that's nothing! My other GN was reading 150! So far I found the seal on the throttle body leaking, behind the TPS sensor, but that's in another post.
Sounds like you are on the right track. You might plug that hole off and put a breather in it for a while just to see if it does run better. It's easy to change back if that ends up not being your problem. But that's gotta be your idle problem, at low rpms those leaks cause huge idling issues.
I didn't care about the stock looking part, I took mine off way back when because I don't want that pos sending oil into my air tract.
I think I figured it out. In order to check for vacuum leaks, you must block off that hole in the turbo bell. That hole sucks in air (and oil from the valve cover), just like where the air filter (and MAF pipe) is connected to. Then after blocking off that hole, I can search for more air leaks. :biggrin:
Black Power
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Hang on, I thought you already said you were blocking off the hole in the turbo bell with your hand?
Yes, I did. but I already had the intercooler removed and plugged the outlet from the turbo to the intercooler. I was wondering where the leak was, so after removing the intercooler, I knew it had to be in the turbo or somewhere close to the turbo. Now I can plug that "pipe" hole in the bell, reconnect the intercooler, and look for more leaks.
Black Power
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Gotcha.
So you have the turbo outlet plugged, and you were blowing air into where, into the turbo inlet? Or into the maf pipe I guess?
Yes, where the MAF pipe connects to. Search for boost leak detector and you will see what I am talking about. Better yet, google it and you will get plans from other car sites on how to build one like I did.
Black Power
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I saw one on evilbay, kinda like a silicone hose that necks down, with a fitting for your air line in the center where you blow the air. Cool little gadget, I should try it on mine.
I made mine similar to this one: How to: make a slightly more baller boost leak detector - evolutionm.net
but instead of the white pvc piece, I went to Lowes and bought a blue rubber toilet bowl plunger for like $1.75, to fit over the turbo inlet.
Your chasing your tail in the wrong direction worrying about a "vacuum" leak on the vent pipe. It's not part of the vacuum system because it sits in front of the throttle body. It's nothing more than a crankcase vent system.
I caught my tail and plugged the hole. Thanks.
Black Power
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But still doesn't want a leak from there, it's coming in after the MAF which is gonna cause trouble.
No, you don't want that nipple on the turbo bell completely open, however, think about where that air comes from.
Plugging it is something that virtually all of us do anyway, to keep oil out of the tubo inlet.
After plugging that hole on the bell, I used my leak detector. I could hear air escaping and sprayed everything with soapy water. Couldn't find the leak. Even used propane and couldn't find it. I'm thinking maybe egr valve, but it is just a guess. Might bring car in to have it "smoked". My other car leaked from the throttle body shaft seals. Ordered those from gbody yesterday.
Great Idea to have it smoked. It will take take a very short time to find it. A typical shop will probably charge between a 1/2 hour to an hour of Diagnostic time to do so. It will be $$ well spent and you will know exactly what is leaking
I wish you were close by, I'd do it for free!
Good Luck, Paul
