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Boost leak question.

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92rsAWD4me

92rsAWD4me

10+ Year Contributor
152
0
Dec 8, 2008
Yucaipa, California
Ok so I have been slowly going through the maintenance on my Laser and solving problems as I find them. One thing I have been having trouble with is boost leaks since the previous owner appears to have done next to nothing in the way of routine upkeep. On my last attempt at a BLT I couldn't get it to hold any pressure and it sounded like there was a big leak near the bottom of the turbo. I sprayed soapy water around there and felt around with my hand but couldn't find anything. What else could this possibly be? The car seems to pull hard (I haven't driven a 1g with no leaks and such so I don't have much to compare it to) and hits fuel cut around 5000 depending on what mood the cars in and how hard I am pushing. Any ideas would be helpful since I need to get passed the big leak before I can start looking for the smaller ones.


When I say "what else could this possibly be" I mean is there something inside the turbo that could be leaking that I would be able to hear but not feel/see.
 
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Have you checked your wastegate? It sounds like its stuck open.
 
It feels to me like it makes boost though.. would it still do that with it stuck open? I will look around the FAQ and such to find how to check for proper waste gate function.

Sorry for the bump but if anyone can help me find a link to how to properly check for waste gate function that would be awesome. Thanks.
 
How quickly does the car leak down? The fuel cut at 5000 a boost leak will cause it. Remove the WG its two bolts and pin. Then hold the lever manaully and do BLT.
 
Ok I will try that. I cant even get it to hold any pressure but I think I need to take the car to the gas station or borrow a compressor. I have a little air tank but I don't think it hold enough air. But I have a pressure gauge on my tester and when I try to pressurize it I hear a lot of air around the turbo area and the gauge maybe gets to 3psi and goes down right away. I think I will try to take it to the gas station and use their air hose tomorrow.
 
I forgot to tell you before. Do this before you remove the WG to. Pressurize the system and put your EAR next to the TAILPIPE. IF the WG is leaking your gonna hear or feel the air.Sorry I forgot to tell you.:coy:

That little air tank can probally do this test
 
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OK thanks.. I think the first step is to take it to a more abundant source of air and try to pressurize it that way and go from there.. will post the results when I get to that point.. maybe tomorrow.



Yeah I think it is like 5 gallon air tank or something like that I will have to look when I get home but when I tried it last time I couldn't get it to hold any pressure. I will have to fill it up and see if I can talk my wife into putting her face by the exhaust for me.
 
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What kind of boost levels are you running? Is it effecting your idle? What you're thinking is fuel cut, could actually just be a boost leak. It wouldn't be the first time someone has made that mistake. Also, you don't even really need to keep messing around with a boost leak test. Just check every connection on your intercooler piping. I mean take them off, put them back on and tighten them down, hard. If its still boost leaking after that, then it could be one of your throttle body gaskets, or the intake manifold gasket. Or as mentioned before, your wastegate could be stuck open.
 
Wait a second... Since when does boost pressure enter the exhaust system? A BLT will most likely NEVER be affected by the wastegate being stuck open. The intake air never comes in contact with the exhaust path... ever, unless your turbo has a giant hole in it from the compressor side to the turbine side.

The ONLY thing i can think of that would remotely cause a boost leak with regards to the wastegate would be a hole in the canister.

A. Do you have a manual boost controller? If so, you need to block off the boost reference line from the intake manifold, otherwise your MBC will bleed off intake pressure.

B. Down near the bottom of the turbo? There are only a few things that I can think of that would cause a boost leak at the bottom of the turbo. The LICP has a hole in it, The wastegate actuator canister has a hole in it, the outlet pipe has a hole in it, or the gasket is blown, or the big ass o-ring for the compressor housing is missing/busted.

C. Check/replace all your vacuum lines. Will save you a ton of headaches later.
 
Why wouldn't an open wastegate affect results of a boost leak? IT's letting ALL THE AIR OUT and INTO your exhaust. I really doubt you will hear the leaking air in your long exhaust btw.

Search the forum, find the proper way to do a boost leak test. Perform the test up to 18 or 20 lbs. I only run 12 lbs but I still BLT to 20 lbs.

Fix your wastegate if needed, sometimes things get loose & that will result in your loosing boost or creeping boost. You could also be losing power due to running to rich (hence boost leak).

Good luck finding your problem. Do not use a bike pump. Use an air compressor. A 3 gal. should be enough to do a quick boost leak test. Especially if your car isn't leaking air :aha:
 
In reference to this "Why wouldn't an open wastegate affect results of a boost leak? IT's letting ALL THE AIR OUT and INTO your exhaust. I really doubt you will hear the leaking air in your long exhaust btw." the compressed air that is going through your intake is not connected to your exhaust stream till it is ran through the motor as a cumbusted gas into the hot side of the turbo. If you hear any noise from you exhaust from a blt its a likely clue that you could have bad exhaust valves.
 
rEclipserGST said:
Why wouldn't an open wastegate affect results of a boost leak? IT's letting ALL THE AIR OUT and INTO your exhaust. I really doubt you will hear the leaking air in your long exhaust btw.

Search the forum, find the proper way to do a boost leak test. Perform the test up to 18 or 20 lbs. I only run 12 lbs but I still BLT to 20 lbs.

Fix your wastegate if needed, sometimes things get loose & that will result in your loosing boost or creeping boost. You could also be losing power due to running to rich (hence boost leak).

Good luck finding your problem. Do not use a bike pump. Use an air compressor. A 3 gal. should be enough to do a quick boost leak test. Especially if your car isn't leaking air :aha:
Click to expand...

Wow, just wow. A wastegate diverts exhaust gasses around the turbine to control boost. A wastegate flapper has nothing to do with a boost leak, ever. It is possible for there to be a boost leak around the compressor housing snapring, or o ring seal. Where are you connecting the boost leak tester? It is possible to pressurize the crankcase if you just stick the tester where the factory maf is, without blocking off the breather lines. If the system will not hold pressure at all, you are probably doing the test wrong. A car with a 100% leak, wont drive out of the driveway without stalling.
 
rEclipserGST said:
I stand corrected. It's a shame I've went this long not fully understanding how the wastegate actually works. Amazing.
Click to expand...

It's ok grasshoppa, learn from your mistakes and wisdom will follow.

In all seriousness, you would be surprised how many people think that the air coming from the turbo is actually exhaust gases. I'm entirely sure that the engine wouldn't like 1300 degree intake temps ROFL.

To the o/p. Where are you hooking up the leak tester, directly to the turbo or somehow to the intake pipe?
 
Directly to the turbo. I have been dealing with a shoulder injury and 12hr shifts at work so I haven't had time to take another look at it just yet. I will try to on my school break coming up and let everyone know what I find. It definitely sounds like it is leaking from below the turbo and I think I am just having a hard time holding the air tank hose on the tester so it isn't building much pressure. I am going to see what I can do to fix this issue as well. The last time I did the test it barely showed any pressure on the gauge on my tester before leaking out but the idle and normal driving are just fine. It is just when I really try to push it and get RPM up it will shut off (fuel cut I assume) around 5000rpm.

No mbc is hooked up and everything is stock as far as hosing and pipes go, and by stock I mean a lot of it is original. I have replaced the vacuum lines however so I don't think that is the issue.
 
Next time you have your intake off check your turbo for shaft play and stick your fingers all up in there and feel around for oil. Another thing to check is the valve cover breather. Take the vacuum hose off of it (the hose that runs from your valve cover to your intake pipe) and plug it with your finger while you pressurize it.


It sounds like you either have a bad turbo, bad pcv valve, or bad rings.
 
92rsAWD4me said:
New pcv, have checked compression, I am suspicious of the turbo. It boosts well so it isn't completely toast but I am pretty sure it is on it's way out. I will update when I get home and look at it.
Click to expand...

Did you test the pcv valve by blowing into it (in the direction of the valve cover)? I ask because I bought a brand new one and blew it wide open in the parking lot of the parts store, imagine what damage 20psi would do.
 
habitatguy187 said:
Did you test the pcv valve by blowing into it (in the direction of the valve cover)? I ask because I bought a brand new one and blew it wide open in the parking lot of the parts store, imagine what damage 20psi would do.
Click to expand...

20psi would murder it and ultimately murder your motor LOL.

OP, if it's a stock turbo, and has the J-pipe on, make sure there's a gasket between it and the turbo, and also check the upper and lower openings on your IC (if it's stock).I took mine off one day to clean it and found a buncha tape on one end. Turns out it had holes in it. $40 and all fixed!
 
Start your boost leak at the throttle body elbow. Once you get that part of the intake to hold boost then go to the turbo inlet and start over.

I'm in a similar boat as you with my turbo on its way out but is still boosting strong. I've been working on a BLT for the past week, before I was boosting 11 psi with the MBC all the way out and on a boost leak test I could only get 3 psi and it wouldn't hold. After testing from the TB forward and replacing the injector seals and tightening a few manifold vacuum lines, I'm now hitting 12 psi with the MBC all the way out and am up to 15 psi on a boost test. Its still a work in progress but just to show you that it does help. Now I'm starting to test from the turbo inlet so I can make sure everything is holding.

Hope this helps!
 
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