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Thread: A little more than a boost leak...

  1. #1
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    Default A little more than a boost leak...

    So it doesn't matter what gear it is in, as soon as I start hitting boost at 1lbs i hear it started to make a whooshing sound or like my tial wastegate is opening up and it stalls out at 5lbs of boost. I checked the threads here and people said it was a boost leak. I replaced all the couplers and Tbolt clamps. I replaced the wastegate, I ran my backup BOV. I took the housing off of the cold side of the turbo and resealed it. My old seal was completely gone and I noticed that my turbo feed line had leaked down a little oil and it got into the cold side housing. I checked the turbo inlet tube for cracks. I checked the vacuums line. I did the soapy water spray down test. i took off the upper intake manifold and gave that a new gasket. I have spent almost 20 hours of time working on it trying to figure it out.
    Are there any other places I should be looking and checking?
    Last edited by SR71blackbird; 05-27-2018 at 01:12 PM.
    1987 turbo coupe 5speed: Boport stage 3 head/2.5 cam , Precision stage 3 50trim .63 turbo, Tial 38mm wastegate, Jangus gutted/ported intake manifolds, 60mm tb, Jangus open dumptube, Jangus 3" elbow, Perrin boost controller,Esslinger adjustable cam pulley, Esslinger small crank pulley, stinger FMI, RFL BOV, Spec stage 3 clutch, B&M short throw, 140 speedo, Walbo 255lph, BBK fpr, 3G alternator, ARP studs. Be faster...

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    This hard to put my head around. I don't understand how an engine can rev up, build boost and stall with increasing throttle movement. It might bog down but it shouldn't stall. A boost leak will cause a rich condition....do you have a wideband? I believe these things are programed to Max out around 11.3 at high loads. At 1-5 psi I would guess you should be anywhere between 14-13:1.

    When you did the soap test.....how much pressure did you apply? You want to try and simulate actual running conditions as close as you can anyway. I know you said you replaced the upper intake gasket......did you get under the car and soap up the lower? It's a pain in the ass to see but they have a tendency to leak.

    I also don't understand how an oil feed line can leak into the compressor.......it can only happen internally if the tubo is in need of freshening up.

    Dumb questions but .....do you have the vac line for BOV refrenced from the intake side of the TB? Not sure if yours is adjustable or set spring pressure ..... Is it possible you have the wrong?

    John

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    Sorry maybe I worded that wrong. The engine doesn't stall out. Bad wording on my part. I was trying to say the boost stalls at 5lbs from 3300ish on the way to 5000rpm (thats as high as i let it go). My A/F gauge drops into the low 11's like it did when I was running 18lbs. So its eating up fuel like under normal boost.
    It idles and cruises like nothing is wrong.
    For the soap test I ducked taped up my shop vac to the charging pipe (it is what youtube said I should do) so i am not sure how much pressure that would apply.
    I didn't soap the lower however.
    For the oil in the turbo, before I cleaned it up, I can see an oil stain running right down into the bottom of my compressor and somehow squeezing in where the gasket should have been. Ive never seen it happen before this.
    I have had my BOV hooked up to the vacuum tree since I put the stinger front mount assembly on a few years back. It is spring pressure.
    1987 turbo coupe 5speed: Boport stage 3 head/2.5 cam , Precision stage 3 50trim .63 turbo, Tial 38mm wastegate, Jangus gutted/ported intake manifolds, 60mm tb, Jangus open dumptube, Jangus 3" elbow, Perrin boost controller,Esslinger adjustable cam pulley, Esslinger small crank pulley, stinger FMI, RFL BOV, Spec stage 3 clutch, B&M short throw, 140 speedo, Walbo 255lph, BBK fpr, 3G alternator, ARP studs. Be faster...

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    Ahhhhhh that makes your first post so much clearer.....I almost feel stupid lol.

    Anyway.....have you tied the factory BCS into the system? This sounds alot like how the BCS controls boost when your set the fuel switch in regular mode. What spring PSI you running in the wastegate?

    As for the oil.....are you talking about the nose piece.....I see your running a non stock turbo....I wasn't sure if your still using that piece .....that's usually where the valve cover breather attaches and would be the only source for oil to get in. If we are talking about the same thing..I don't recall a gasket on the stock set up.

    John

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    lol my bad for that...
    I have never used the factory BCS system. Even when I bought the car in 2009, the guy wasn't using the BCS. The spring is set at 14lbs but using my boost controller I had it set to 18lbs.
    oh no nose piece. It leaked from the oil feed line and down the back of the compressor housing and into the compressor. I have had the same setup now for about 6 years and out of the blue this problem started a month ago.
    1987 turbo coupe 5speed: Boport stage 3 head/2.5 cam , Precision stage 3 50trim .63 turbo, Tial 38mm wastegate, Jangus gutted/ported intake manifolds, 60mm tb, Jangus open dumptube, Jangus 3" elbow, Perrin boost controller,Esslinger adjustable cam pulley, Esslinger small crank pulley, stinger FMI, RFL BOV, Spec stage 3 clutch, B&M short throw, 140 speedo, Walbo 255lph, BBK fpr, 3G alternator, ARP studs. Be faster...

  6. #6
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    Ok thanks for entertaining my questions.....it is definitely sounding alot like a boost leak. Since you have done the basic checks I suspect the BOV is the possible culprit. I know you replaced it but if possible try a different vac source preferably directly off the intake. If possible I would remove it completely and test again. If you don't get proper balance on the valve, boost will force it open. The only other thing that comes to mind, not likely but is a possible cracked turbine housing that's opening up as it heats under boost.

    If you have a small air compressor you can make a pressure testing cap with a coupler, plumbing cap and a Barb fitting to attach directly to the snout of the turbo. I don't think the shop vac will reveal anything since It can't make pressure.

    Keep us posted.....I'd like to hear what turns up

    John

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    well I changed the lower intake gasket, upper intake gasket and the TB gasket... I ended up finding a little leak in the vacuum tree and a little leak leading into the front mount. fixed both of them. However... nothing changed.
    Still as soon as I hit 1lb of boost i can still here the start to the wwwsshhhhh sound and it is maxing out at 5lbs...
    How likely can it be that it is my exhaust housing on my turbo?
    1987 turbo coupe 5speed: Boport stage 3 head/2.5 cam , Precision stage 3 50trim .63 turbo, Tial 38mm wastegate, Jangus gutted/ported intake manifolds, 60mm tb, Jangus open dumptube, Jangus 3" elbow, Perrin boost controller,Esslinger adjustable cam pulley, Esslinger small crank pulley, stinger FMI, RFL BOV, Spec stage 3 clutch, B&M short throw, 140 speedo, Walbo 255lph, BBK fpr, 3G alternator, ARP studs. Be faster...

  8. #8
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    It is possible but not likely to be the turbine housing. To get the wooosh you describe, you would need alot of back pressure after the turbo. If anything it could be between the head and turbo flange including your wastgate ...this is where back pressure is usually highest. I think is should sound more like an exhaust leak than a wooosh. As a precaution...make sure everything is tight. Maybe even take the wastegate apart and clean it up so you can inspect the diaphragm.

    I hate that you did all that work and didn't find a fix......did you try eliminating the BOV yet?

    John

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    I went back and re-read your posts.....I don't want to make assumptions and .you don't comment on how it runs under the boost conditions you describe. Does it actually feel down on powert? Have you hooked up a different guage to see if they agree? What's the possibility everything is fine and your dealing with a guage issue?

    John

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    Yes it feels down on power.
    Well I just ran a tube from the turbo straight to the TB and I have the same problem. So the problem isn't in the charge piping...
    1987 turbo coupe 5speed: Boport stage 3 head/2.5 cam , Precision stage 3 50trim .63 turbo, Tial 38mm wastegate, Jangus gutted/ported intake manifolds, 60mm tb, Jangus open dumptube, Jangus 3" elbow, Perrin boost controller,Esslinger adjustable cam pulley, Esslinger small crank pulley, stinger FMI, RFL BOV, Spec stage 3 clutch, B&M short throw, 140 speedo, Walbo 255lph, BBK fpr, 3G alternator, ARP studs. Be faster...

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