Boost leak test help

[97gsx_zeclipse]

I notice that when driving I hear the turbo spooling loud, and a loud hissing that gets louder as I boost more. I also notice that I'm only boosting 8 psi compared to the 14 psi I had it at. So I do a boost leak test. I pressurized the turbo inlet and the gauge only goes to 2 psi and drop immediatley. So I decided to just start at the TB and work my way back to the turbo. I spray soapy water on the TB, all the vacumn hoses, injectors, and basically everything behind the TB. The gauge goes up to 5 psi and drops quickly. But I did find 3 noticable leaks bubbling. The TB gasket between the elbow and TB, a vacumn hose and the idle ajustment screw. Now my question is, is it supposed to leak at the IAC? It was the worst one so far, it was bubbling alot.

My other question is how do I check to see if the intake mani gasket is leaking? Its hard to see it, but I heard its a common place to check. Should I be worried about the PCV valve? I replaced it about 6 months ago with an oem one and also put a check valve between the PCV valve and the intake mani.

And plus I didn't turn my crank 30 degree TDC. Is it neccessary? How do I know if its 30 degrees TDC?

Thanks for all the help guys.

 

[Black99gst]

I notice that when driving I hear the turbo spooling loud, and a loud hissing that gets louder as I boost more. I also notice that I'm only boosting 8 psi compared to the 14 psi I had it at. So I do a boost leak test. I pressurized the turbo inlet and the gauge only goes to 2 psi and drop immediatley. So I decided to just start at the TB and work my way back to the turbo. I spray soapy water on the TB, all the vacumn hoses, injectors, and basically everything behind the TB. The gauge goes up to 5 psi and drops quickly. But I did find 3 noticable leaks bubbling. The TB gasket between the elbow and TB, a vacumn hose and the idle ajustment screw. Now my question is, is it supposed to leak at the IAC? It was the worst one so far, it was bubbling alot.

My other question is how do I check to see if the intake mani gasket is leaking? Its hard to see it, but I heard its a common place to check. Should I be worried about the PCV valve? I replaced it about 6 months ago with an oem one and also put a check valve between the PCV valve and the intake mani.

And plus I didn't turn my crank 30 degree TDC. Is it neccessary? How do I know if its 30 degrees TDC?

Thanks for all the help guys.

some of the issues in your post are irrelevent, however, if you simply read the tech articals on this, you would be able to find all of your answers if not more. as for the pressure only "reading 2psi on the gauge" what gauge? the one on the compressor of the one in the car? make sure the air line is connected fully to your "leak tester" this could cause this issue. as for the IAC, i dont know, but mine doesnt! and as for IM Gasket, i have never checked it, only replaced it when i changed my cams (because i did the HG at the same time with ARPs ) so i would go with "its fine" PCV valve as you will read in the techs should be bypassed prior to the leak down test.

30* TDC for a boost leak test???? come on! dont waste your energy!

i'll bet since you here a whistle, your problem is a little leak in a cuppler that you cant notice when its not pressured because the leak is so small, check hot pipes (pipes between turbo and intercooler) and i'll bet you find your PITA there...

 

[turboglenn]

Well, what you're trying to get to is 30* ATDC.... TDC is top dead center = 0*, so there can be no 30* TDC, it's either before or after hence teh Btdc and Atdc. As for the 30* you need. Each cam gear tooth is about 5-7* of revolution at the crank. So you could line up the timing marks and then turn the motor clockwise and watch and count between 5 and 6 cam gear teeth moving past a set marker point ( edge of the head or something)

Then try your test again. If you still can't get it, have the BLT'er hooked up and move the motor till it has the least amount of leakage from valves and do it that way

 

[kenamond]

I've never had to manually crank the motor to 30°ATDC for a BLT. If you were having a valve overlap issue, you wouldn't build any pressure; the air would go out the exhaust.

I've *never* bypassed my PCV valve during a test, as the PCV valve is a very common problem that BLTs will identify. I'd pull it from the VC before the test just so you can see if anything is leaking from it. If it is, you can cap it to test for other leaks and to find out if the valve was your major problem (and then replace it). But since you have a new valve plus a check valve (assuming you have the check valve in the right direction), I doubt that's the problem.

I assume you're checking BLT pressure with the boost gauge (aftermarket only), as that's the pressure you care about (not the compressor pressure).

And since you're testing at the TB elbow, it can't be a coupler. Fix any leaks you find; they may seem smaller than they actually are.

 

[97gsx_zeclipse]

some of the issues in your post are irrelevent, however, if you simply read the tech articals on this, you would be able to find all of your answers if not more. as for the pressure only "reading 2psi on the gauge" what gauge? the one on the compressor of the one in the car? make sure the air line is connected fully to your "leak tester" this could cause this issue. as for the IAC, i dont know, but mine doesnt! and as for IM Gasket, i have never checked it, only replaced it when i changed my cams (because i did the HG at the same time with ARPs ) so i would go with "its fine" PCV valve as you will read in the techs should be bypassed prior to the leak down test.

30* TDC for a boost leak test???? come on! dont waste your energy!

i'll bet since you here a whistle, your problem is a little leak in a cuppler that you cant notice when its not pressured because the leak is so small, check hot pipes (pipes between turbo and intercooler) and i'll bet you find your PITA there...

Well what I meant by the gauge reading 2psi is the gauge I put on the boost leak tester. At the turbo inlet it read 2 psi and at the TB it read 5 psi.

AS for TDC, I meant ATDC.

As for the whistling noise, its really loud. You can hear it on the freeway with the windows rolled up, with the radio on.

Thanks for the help.

 

[97gsx_zeclipse]

I've never had to manually crank the motor to 30°ATDC for a BLT. If you were having a valve overlap issue, you wouldn't build any pressure; the air would go out the exhaust.

I've *never* bypassed my PCV valve during a test, as the PCV valve is a very common problem that BLTs will identify. I'd pull it from the VC before the test just so you can see if anything is leaking from it. If it is, you can cap it to test for other leaks and to find out if the valve was your major problem (and then replace it). But since you have a new valve plus a check valve (assuming you have the check valve in the right direction), I doubt that's the problem.

I assume you're checking BLT pressure with the boost gauge (aftermarket only), as that's the pressure you care about (not the compressor pressure).

And since you're testing at the TB elbow, it can't be a coupler. Fix any leaks you find; they may seem smaller than they actually are.

I didn't think cranking the motor 30 degrees ATDC is neccessary either.

I am checking the pressure with a gauge on the boost leak tester.

 

[kenamond]

Have you done a compression test?
Did you do the BLT on a fully warmed-up motor?
Do you hear any hissing during the BLT?

 

[97gsx_zeclipse]

I did the BLT on after a 20 min drive. I heard no hissing at all. I'm surprised I didn't hear anything because under boost I hear a loud hissing noise. I haven't done a compression test. I'm going to do annother BLT today and fix the TB leaks. Is it ok to wrap the idle adjustment screw with teflon? I heard that the tape may melt? Thanks

 

[kenamond]

I did the BLT on after a 20 min drive. I heard no hissing at all. I'm surprised I didn't hear anything because under boost I hear a loud hissing noise. I haven't done a compression test. I'm going to do annother BLT today and fix the TB leaks. Is it ok to wrap the idle adjustment screw with teflon? I heard that the tape may melt? Thanks

You can get BISS o-rings at the hardware store. I think they're #5, but you could check VFAQ (that's where I found out that trick). I don't think you should use teflon tape. I'll see if I can find the VFAQ article. It's near the bottom of one of the articles.

All the way at the bottom of the article, it mentions the o-ring size (#5) and the Mitsu part number:
http://www.vfaq.com/mods/BISS-2G.html

 

[Steelnation36]

Quick question.... what are the signs of a boost leak? like while your driving, what to look and/or listen for? Ive never had one that i know of dont seem to have any problems as far as that goes but for future reference

 

[numlock666]

Sluggishness. Hop in a car that has a perfect IC system with no leaks. You really don't notice until it becomes a big problem.

 

[kenamond]

Quick question.... what are the signs of a boost leak? like while your driving, what to look and/or listen for? Ive never had one that i know of dont seem to have any problems as far as that goes but for future reference

You can't claim that you have no leaks unless you've done a successful BLT. As numlock666 said, you'll just run slower than without leaks. Do a BLT, fix all the leaks, and enjoy a bit more pull.

 

[talonalex92]

http://www.vfaq.com/mods/BISS-2G.html

Yeah, its a #5 and it cost me about 41 cents @ ace hardware.

 

[97gsx_zeclipse]

I heard its common for the 2g to leak at the intake manifold gasket. When I'm doing a BLT its hard to see the mani gasket. how do you check for it?

 

[kenamond]

I heard its common for the 2g to leak at the intake manifold gasket. When I'm doing a BLT its hard to see the mani gasket. how do you check for it?

I think you should just do the BLT and see what's leaking. If it's not leaking badly, you can use a spray bottle with super-soapy water in it (I use dish soap). Spray the common areas and look for bubbles. If it's leaking badly, listen for hissing.

You can spray the top of the IM gasket and the injector insulators while you're at it, but I'm not sure how to see the bottom of the gasket. Mine doesn't leak, so I haven't had to worry about it. I fixed all the leaks I could find and then could hold 20psi and leak at about 1psi every 4-5 seconds, so I never worried about the IM gasket. Maybe yours won't leak either.

 

[97gsx_zeclipse]

I wish mine could do that. It goes to 5 psi and goes to zero with 2 seconds. You can totally feel the sluggishness in my car. I doesn't even pull anymore, you know at that certain rpm where it just kicks in hard, yeah that hasnt happened in awhile. Its hard to find time to fix these damn leaks for I work 60 hour weeks. But yeah I'm going to do a full BLT and fix the leaks this weekened for sure.

 

[kenamond]

I wish mine could do that. It goes to 5 psi and goes to zero with 2 seconds. You can totally feel the sluggishness in my car. I doesn't even pull anymore, you know at that certain rpm where it just kicks in hard, yeah that hasnt happened in awhile. Its hard to find time to fix these damn leaks for I work 60 hour weeks. But yeah I'm going to do a full BLT and fix the leaks this weekened for sure.

My prediction is that the PCV valve, injector insulators, and TB gasket are all leaking.

Make sure you cap off the MBC line off of the compressor outlet or j-pipe.

 

[90GSTBoosted]

Or the valve seals are going out.

 

[Black99gst]

you have a boost leak somewhere and its very small, which is why it is so loud, could be from a pin sized hole in a cuppler, or a pinched cuppler from the clamp... i can almost promis you its before the intercooler... a leaky valve would have a different sound the a "loud whistle" any the compression test is irrelevent since you are hearing a whistling noise.... what i would do is pull the hot pipes (from turbo to intercooler) all appart, and clean them up, then take a good look at the cupplers (play around with them, twist them, pull on them and look for holes), then peace by piece put it back together, using PLEANTY of hair spray on each pipe and cuppler, then clamp the bitches down... if you dont find a hole in one of the cupplers, i can almost 100% promis you this problem will still be solved

 

[Steelnation36]

yeaaa id agree with the above my friends tsi had that issue i cringed when i was in the car haha

 

[kenamond]

you have a boost leak somewhere and its very small, which is why it is so loud, could be from a pin sized hole in a cuppler, or a pinched cuppler from the clamp... i can almost promis you its before the intercooler... a leaky valve would have a different sound the a "loud whistle" any the compression test is irrelevent since you are hearing a whistling noise.... what i would do is pull the hot pipes (from turbo to intercooler) all appart, and clean them up, then take a good look at the cupplers (play around with them, twist them, pull on them and look for holes), then peace by piece put it back together, using PLEANTY of hair spray on each pipe and cuppler, then clamp the bitches down... if you dont find a hole in one of the cupplers, i can almost 100% promis you this problem will still be solved

He can't hold more than 5psi at the TB elbow - after the IC pipes.

 

[97gsx_zeclipse]

Well I do have a check valve between the PCV valve and manifold. I checked the check valve and its still good, best 3 bucks I've ever spent. Can hold up to 75 psi easy. But other than that, its hard to believe its a leak that small. I didn't hear any hissing when doing a BLT. I found a few small leaks at the TB, fixed those and still no difference. If you drove my car you would think its a powerful non turbo GSX haha. I'm pissed because I put so much mods on this car and evo's can beat me now. I'm kinda embarrassed for I own a DSM and can't find a leak that big by doing a simple BLT. I read a similar thread, the guy had the same problem and found the leak at the EGR, it was open. I haven't even checked that. But couldn't you hear a leak that big when doing a BLT?

 

[kenamond]

Did you check your compression yet?

When you do the BLT, pull the PCV out and just check it (if you haven't) just to rule that out. Then reinstall it. Then pull the VC breather off and leave the oil fill cap on and add pressure. See if the air is coming out of the VC breather. If your compression is good, I'd suspect intake valve stem seals. If the compression is bad, add a spoonfull of oil like a wet compression test and repeat the test and see if that helps. If it does, it's blowby from poor ring sealing. If it doesn't, it sounds like intake valve stem seals again.

Did you spray soapy water on the injector bases to see if the insulators were leaking? If you haven't changed them, I'm sure they're leaking.

I don't know dick about the EGR, so I'll ask some complete newbie questions. Does the EGR run to the charcoal canister and then to the intake pipe? If so, couldn't you pull the hose off of the intake pipe, do the test, and see if air comes out of that hose? If I have it all wrong, someone feel free to explain it so that I'll know one more thing about my car.

Finally, do you have someone who could stick their head under the hood and listen when you add air? They might be able to hear something up close.

 

[97gsx_zeclipse]

Did you check your compression yet?

When you do the BLT, pull the PCV out and just check it (if you haven't) just to rule that out. Then reinstall it. Then pull the VC breather off and leave the oil fill cap on and add pressure. See if the air is coming out of the VC breather. If your compression is good, I'd suspect intake valve stem seals. If the compression is bad, add a spoonfull of oil like a wet compression test and repeat the test and see if that helps. If it does, it's blowby from poor ring sealing. If it doesn't, it sounds like intake valve stem seals again.

Did you spray soapy water on the injector bases to see if the insulators were leaking? If you haven't changed them, I'm sure they're leaking.

I don't know dick about the EGR, so I'll ask some complete newbie questions. Does the EGR run to the charcoal canister and then to the intake pipe? If so, couldn't you pull the hose off of the intake pipe, do the test, and see if air comes out of that hose? If I have it all wrong, someone feel free to explain it so that I'll know one more thing about my car.

Finally, do you have someone who could stick their head under the hood and listen when you add air? They might be able to hear something up close.

I haven't done a compression test yet. I will soon. I sprayed soapy water on injector seals, do we have 3 injectors? thats all I see. I haven't changed them since I bought the car 2 years ago. Should I replace them anyway?

 

[kenamond]

I haven't done a compression test yet. I will soon. I sprayed soapy water on injector seals, do we have 3 injectors? thats all I see. I haven't changed them since I bought the car 2 years ago. Should I replace them anyway?

There are four. The fuel rail should be plainly visible between the valve cover and intake manifold. There should be four injectors between it and the head, and there should be one electrical plug plugged into each of the four injectors. When you sprayed water, did it foam up around the bottom of the injectors where they stick into the head? I wouldn't expect them to leak after two years though. Below is a link showing where the rail is.

http://members.shaw.ca/dsm.1000q/Engineprimer/2G/fuelrail.htm

Do that compression test and post the results. Make sure the motor is fully warmed up. If you need any more details, do a Google search of "dsmgrrrl compression" for a good site describing the process, what good compression is on a 2g, etc. If compression is low, do a wet test and see if it's rings or something else. Again keep us posted with results.