2G Turbo and O2 housing Gasket Leaks

[tgounev]

The symptoms: The car would spool slow and can’t reach the max boost. Used to max at 24-25 psi – now it goes to 19-20 psi. You can hear a whoosh sound during boost – like something is deflating. The A/F gauges show lean condition during idle, which forces the LTFT to keep adding fuel, but the A/F ratio is fine during cruise and WOT.

What I did: First, I did a boost leak test and found leaks in the throttle body. I sent the TB to be refurbished (shaft seals, etc.) and when it came back, the intake leaks were gone. The BLT held good until 22 psi where the BOV starts to leak (I think that’s normal for 1G BOV, please correct me). Second, realizing that I must have an exhaust leak, I tested it with a shop-vac in the exhaust pipe and soap water. I had leaks on the exhaust manifold gasket and the turbo and O2 housing gaskets. I replaced all 3 gaskets. Had to put a helicoil in one of the manifold stud holes as it was stripped, which caused the leak on the manifold gasket, then used a Fel-Pro gasket for the manifold. Got the other 2 gaskets from ebay. They looked thinly made out of one layer steel. Put everything back and torqued the turbo and O2 bolts to 42 ftlb. Went for a test drive – same problem (maybe even slightly worse). I tested the exhaust side for leaks again. No leaks on the manifold gasket, but the turbo and O2 housing gaskets were leaking just as bad as before.

I am out of ideas. It has to be the exhaust leak. Would such a leak cause a 5 psi drop in boost and very lean idle? If it’s the gaskets, are there any more “forgiving”, thicker and softer gaskets I can use on the turbo-to-manifold and turbo-to-O2 surfaces? Thanks.

 

[turtlebain]

Would personally try better gaskets. There's little I'd trust eBay quality to. Generally my trust stops at pipes. What surface prep are you doing on gaskets and mating surfaces before installing? If there are imperfections you might have to resurface or replace.

I got a crush gasket at STM for my O2 to down pipe. It was the best thing, because I have the Megan Racing downpipe that is before their revision and prone to exhaust leaks. I'll see if I can get you a link.

 

[turtlebain]

http://www.streettunedmotorsports.com/parts/remflex_exhaust_gaskets_8055_8006.htm

Believe this is what I got

REMFLEX 2-BOLT EXHAUST GASKETS
$9

Just specify your down pipe size.

 

[tgounev]

My problem is not the gasket to the downpipe. It's the 4-bolt gaskets between turbo and O2 howsing and between turbo and exhaust manifold. I don't think the surfaces are warped, but there were some imperfections. I tried to clean them up with a Scotch-bright pad, but there are still some imperfections. I found a site that sells copper gaskets (FFWD connection), but the turbo to manifold gasket is out of stock.

 

[turtlebain]

My problem is not the gasket to the downpipe. It's the 4-bolt gaskets between turbo and O2 howsing and between turbo and exhaust manifold. I don't think the surfaces are warped, but there were some imperfections. I tried to clean them up with a Scotch-bright pad, but there are still some imperfections. I found a site that sells copper gaskets (FFWD connection), but the turbo to manifold gasket is out of stock.

OK, so I'd get a new gasket, OEM is the most trusted. And if there are imperfections you should be able to block sand them, at least to 300 grit. Bigger the block the better. The reason scotch brite isn't preferred is you could be actually making the imperfections worse. With a block it will be flat. That with copper spray and you should be good to go. But getting rid of surface imperfections should make it so you no longer need the spray.

 

[turtlebain]

You can get Copper spray at any local automotive store.

 

[turtlebain]

Here it is at AutoZone

http://www.autozone.com/sealants-gl...a-gasket-hi-temp-adhesive-sealant/520940_0_0/

 

[tgounev]

OK, I will see if I can true the surfaces, although I am a little scared to take sandpaper on them. But I will try to get these copper gaskets (from FFWD, made by SCE), as people say they easily seal imperfections, and maybe use copper spray along with them for additional sealing power. I am going out of town for 10 days, so I'll work on this when I come back. BTW, I forgot to mention that the flex section on the downpipe is leaking too, but this shouldn't affect my boost or the O2 readings, only the wide band sensor which is after the flex section.

 

[curt-s]

Only if you're tuning based on those readings, but if your tune is static, then no. (Not patronizing, just general info for the public)

 

[turtlebain]

You'll want to fix the flex pipe too it will affect wide band O2 numbers. Don't be afraid to sand it, just have various grits ready to bring it out to around 300 grit, higher if you want a better seal. Sanding in a criss-cross pattern will ensure you don't leave large scratches. sand one way until you can't see the other marks anymore. Clean up with denatured alcohol and blow compressed air through the pipe to make sure there's no shavings left over. It's pretty simple, just takes some time.

 

[portum89]

coper spray it should fix the leak. i dont see how they would warp, if anything they would crack.

 

[darknezz7]

Id recommend the 6 layers mls manifold to turbo gasket. Had the same problems with those single layer or aluminum crush gaskets just blowing out and not sealing.

You must be logged in to view this image or video.

http://www.extremepsi.com/store/product.php?productid=29669&cat=0

Also like ppl have said, a wire wheel and sand paper to both surface sides


also you wideband should be before the flex, right after the turbo, a lot of people just use the stock o2 housing, faster reading and less leaks. The flex pipe leak WILL make the wideband read lean.

 

[tgounev]

Guys, before I put the new gaskets I wanted to test my wastegate. A month ago I tested the actuator with compressed air. It starts opening the gate at around 15 psi and the gate is fully open around 18 psi. Is this normal for a big 16G turbo? I used to be able to boost to 24-25 psi, now I get to only 19-20. I am suspicious of the wastegate because this 5-6psi difference seems to me a little too much to be from just exhaust leaks.

 

[GRAVEDIGGER]

Guys, before I put the new gaskets I wanted to test my wastegate. A month ago I tested the actuator with compressed air. It starts opening the gate at around 15 psi and the gate is fully open around 18 psi. Is this normal for a big 16G turbo? I used to be able to boost to 24-25 psi, now I get to only 19-20. I am suspicious of the wastegate because this 5-6psi difference seems to me a little too much to be from just exhaust leaks.

Weren't you using a boost controller to get the boost to 24-25 in the past? Usually those wastegate actuators have around a 12-15psi spring in them, so that's where they open and to get anything else you'd need to have a boost controller.

 

[tgounev]

Yes, yes... I have a manual boost controller under the hood with a hard cable that goes into the cabin so I can control it at any time. It's set to the max boost .... unless it's malfunctioning somehow. I can lower the boost, I just can't get it any higher. OK, so 15 psi is ok for the spring tension on the waste gate, and I can relax about it.

 

[GRAVEDIGGER]

You can only effectively double the wastegate spring pressure by using a boost controller in most cases. So you most likely have about a 12lb spring which you are doubling with the boost controller maxed out to reach 24-25psi. I think it still may be a problem with the boost controller. Maybe if you adjust the controller down a bit you can get it to come back over 20psi on the boost. It may just be too far maxed and is bleeding off too much boost.

 

[tgounev]

I will check on that when I put the parts back together. As I was looking at the wastegate, I noticed two vertical cracks right above and below the wastegate opening in the turbo howsing. The cracks are visible on both sides of the wastegate opening. I am attaching 2 pictures looking from both sides (inlet and outlet of wastegate). Do you guys think these cracks are big enough to explain 5 psi lower max boost?
http://g.web.umkc.edu/gounevt/car/P6140364.JPG
http://g.web.umkc.edu/gounevt/car/P6140363.JPG

 

[tgounev]

OK, I have the turbo and O2 housings sealed (sanded surfaces, copper gaskets, copper spray). I still can't get over 18-19 psi. The cracks around the wastegate hole might be a problem, but I doubt it. I went back to to the intake side and did another BLT, this time concentrating on the EGR and the BOV. As I was listening closely to the BOV, I can hear some sshhhh noise starting at 14-15 psi which gradually increases and the valve opens at 22 psi. I don't know if this is normal for 1G BOV, but its very suspicious. I am thinking of getting a new 1G BOV (or should I get something else that fits on the 1G flange?) Any suggestions are appreciated.

 

[bratte88]

You'll want to fix the flex pipe too it will affect wide band O2 numbers. Don't be afraid to sand it, just have various grits ready to bring it out to around 300 grit, higher if you want a better seal. Sanding in a criss-cross pattern will ensure you don't leave large scratches. sand one way until you can't see the other marks anymore. Clean up with denatured alcohol and blow compressed air through the pipe to make sure there's no shavings left over. It's pretty simple, just takes some time.

second this*

 

[turtlebain]

I would think you'd want to replace a cracked O2 housing.. Why not fix what you know is broken first?

 

[tgounev]

I did all the sanding, etc., and there are no external leaks at the turbo and O2. The cracks are on the inside of the turbo housing at the wastegate hole, so I would have to replace the turbo housing. I would kick myself if I replace it, and later find that the BOV is leaking my boost, not these cracks. I'll have to buy a BOV to find out for sure, but I was thinking of "crushing" the old BOV first to see if strengthening the spring would give me more boost. Why do BOV's leak? Is it just the spring getting weaker over time, or there could be other reasons for poor sealing?

 

[GRAVEDIGGER]

That crack at the wastegate hole can definitely cause your problem. That must seal up all the way in order to build proper boost pressure. That is the same as the wastegate flapper door not closing all the way. It is essentially always partially open.

As for the BOV... Crush it and forget about it. I currently have a crushed 1g bov that holds 28psi no problem.

 

[turtlebain]

That crack at the wastegate hole can definitely cause your problem. That must seal up all the way in order to build proper boost pressure. That is the same as the wastegate flapper door not closing all the way. It is essentially always partially open.

As for the BOV... Crush it and forget about it. I currently have a crushed 1g bov that holds 28psi no problem.

I agree 100% this is the source of all your pressure , bro, I don't know what to tell you. Cracks in your turbo and O2 housing are not "normal" so I would replace it if it's not causing this boost malfunction or not, on the other hand, simply doing a blt can show you if your bov is leaking and at what psi. Let us know if you need any more help. Gl.

 

[turtlebain]

So I just went up to see and it says you did a blt already and it held to 22 psi.. So the bov is not your issue then if you're having trouble in the 15-18 range.

 

[1990TSIAWDTALON]

Sounds for sure like the cracks are the culprit. You can always cap off the bov with something and then do a blt which would take the bov out of the equation. If that 1g bov isn't crushed then it can definitely hold more.