Exhaust leak with Helix DP and stock catback

na-STi · 04-26-2006, 09:51 AM

I tried searching for the info I need but could not find it.

I recently had a catted Helix DP installed to my stock catback and my installer said that I would get a small exhaust leak but I would not lose any power. I know that I am getting an exahust leak because when I warm up my car in the morning, water drips on the floor where the DP and CB meet. I also hear a weird noise when driving sometimes.

Is there a way to fix this? I don't want to get an aftermarket CB right now. Should I even be concerned?

klaymon · 04-26-2006, 10:06 AM

There's a leak because the DP uses a flat flange and the OEM cat back uses a donut flange. They are not 100% compatible. To be sure of completely stopping the leak, get an after market exhaust with a flat flange to mate up, have a flat flange welded on the OEM cat back, or go back to the stock DP.

na-STi · 04-26-2006, 02:22 PM

Will having this leak cause any major problems that I should be concerned with?

klaymon · 04-26-2006, 07:31 PM

Not that I'm aware of other than exhaust fumes right under your nose while you sit at a light.

Titleist71 · 04-26-2006, 08:27 PM

get a donut gasket or use hi-temp RTV and gob it on the flange, and tighten it. I would use an impact to make sure its tight.

na-STi · 04-26-2006, 10:32 PM

Quote:

Originally Posted by Titleist71

get a donut gasket or use hi-temp RTV and gob it on the flange, and tighten it. I would use an impact to make sure its tight.

Where do I get this donut gasket and hi-temp RTV?

jsh139 · 04-27-2006, 05:53 AM

I don't think the donut gasket will help because there's nothing to hold it on to the DP. The stock DP to catback connection uses spring bolts and that donut gasket. It's kind of like a ball and socket connection. The donut gasket is held onto the downpipe by a little lip. That lip is what's missing from the Helix flange. I dunno, I guess you could cram one in there but what I'm trying to say is that there's no bolts to hold in the gasket like the normal flange gaskets. I guess that's what the RTV is for?

kinger · 04-27-2006, 06:05 AM

This was my reservation with the helix, the only way to make fit is get a midpipe like the madad where it will have the flat flange on it then go through a flex joint then gradually taper back to 2.5" to mate up with your axle back. You then have a 'stealthback' peiced together. That flat flanged connection will not work with the stock mid pipe no matter what you do.

Titleist71 · 04-27-2006, 09:16 AM

well on one side the stock side the donut will seal. On the other side with the flat flange I would use RTV. You can get it napa. I used the gasket with my catback and it had a flat flange and I had no problems. Now I have a full TBE so I just have RTV to seal it. I have driven the car and have no problems with leaks.

RBMike · 04-27-2006, 10:11 AM

How long ago did you have it installed? I ask because I have the same setup & mine does NOT leak at all.

na-STi · 04-27-2006, 09:04 PM

Quote:

Originally Posted by RBMike

How long ago did you have it installed? I ask because I have the same setup & mine does NOT leak at all.

I had it installed about 2 weeks ago. How did you install it to not get a leak?

VetteVert · 04-28-2006, 04:17 AM

I had the same setup on my old WRX for 20k miles. No leaks.

Did you use regular bolts, or reuse the spring bolts? You HAVE to use regular bolts to get a tight seal.

What kind of gasket did you use? I used the ones provided by GRUPPE-S with the Helix downpipe. If you reused the stock gasket, try a new one.

Helix has changed versions of their DPs so much I'm not sure where you have mount points, but on mine there was a mid-mount flange on the DP. The hole was oval and allowed for some adjustment. The proper mounting procedure for this type of DP is to hang it in place, install all DP -> Turbo bolts and torque (for a good seal), connect DP -> catback, and adjust mid-mount so that the flat plate of the DP is as flat as possible to the catback and torque the DP -> catback bolts.

VV

RBMike · 04-28-2006, 07:18 AM

I did it exactly the way Vettevert discribes above. I used the gaskets & hardware that came with the DP.

na-STi · 04-28-2006, 03:20 PM

Quote:

Originally Posted by VetteVert

I had the same setup on my old WRX for 20k miles. No leaks.

Did you use regular bolts, or reuse the spring bolts? You HAVE to use regular bolts to get a tight seal.

What kind of gasket did you use? I used the ones provided by GRUPPE-S with the Helix downpipe. If you reused the stock gasket, try a new one.

Helix has changed versions of their DPs so much I'm not sure where you have mount points, but on mine there was a mid-mount flange on the DP. The hole was oval and allowed for some adjustment. The proper mounting procedure for this type of DP is to hang it in place, install all DP -> Turbo bolts and torque (for a good seal), connect DP -> catback, and adjust mid-mount so that the flat plate of the DP is as flat as possible to the catback and torque the DP -> catback bolts.

VV

Not sure which bolts my installer used. Will I be able to tell if I just look under the car?

***JDM-STI*** · 04-28-2006, 04:27 PM

If all else fails, get a flex pipe and a flat 2-bolt flange and have it welded on to you CB in place of the stock flange. That would be the best and most reliable fix.

04-26-2006, 09:51 AM	#1
na-STi Professional STI Driver Posts: 498 IWSTI Addict since: Apr 2004 Trader Rating: (0)	Exhaust leak with Helix DP and stock catback I tried searching for the info I need but could not find it. I recently had a catted Helix DP installed to my stock catback and my installer said that I would get a small exhaust leak but I would not lose any power. I know that I am getting an exahust leak because when I warm up my car in the morning, water drips on the floor where the DP and CB meet. I also hear a weird noise when driving sometimes. Is there a way to fix this? I don't want to get an aftermarket CB right now. Should I even be concerned? This ad is not endorsed by this member. Please register or login to hide this ad.

04-28-2006, 04:27 PM	#15
*JDM-STI* Platinum Member Car: 2005 & 2008 STI Fav Mod: Scott Siegel Tuning!!! :D Location: Columbus, GA Posts: 2,020 IWSTI Addict since: Mar 2005 Trader Rating: (11)	If all else fails, get a flex pipe and a flat 2-bolt flange and have it welded on to you CB in place of the stock flange. That would be the best and most reliable fix. This ad is not endorsed by this member. Please register or login to hide this ad.

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04-26-2006, 10:06 AM	#2
klaymon S204 Racer Posts: 3,075 IWSTI Addict since: Jul 2004 Trader Rating: (1)	There's a leak because the DP uses a flat flange and the OEM cat back uses a donut flange. They are not 100% compatible. To be sure of completely stopping the leak, get an after market exhaust with a flat flange to mate up, have a flat flange welded on the OEM cat back, or go back to the stock DP.

04-26-2006, 02:22 PM	#3
na-STi Professional STI Driver Posts: 498 IWSTI Addict since: Apr 2004 Trader Rating: (0)	Will having this leak cause any major problems that I should be concerned with?

04-26-2006, 07:31 PM	#4
klaymon S204 Racer Posts: 3,075 IWSTI Addict since: Jul 2004 Trader Rating: (1)	Not that I'm aware of other than exhaust fumes right under your nose while you sit at a light.

04-26-2006, 08:27 PM	#5
Titleist71 Professional STI Racer Car: 05 PSM STi w/ custom Fav Mod: TiaL 38mm vented free as a bird. Location: Maine Posts: 622 IWSTI Addict since: Mar 2005 Trader Rating: (1)	get a donut gasket or use hi-temp RTV and gob it on the flange, and tighten it. I would use an impact to make sure its tight.

04-27-2006, 05:53 AM	#7
jsh139 How YOU Doin? Car: 2006 Audi S4 Fav Mod: OMGHI2U! Location: Philly 'burbs Posts: 7,710 IWSTI Addict since: Apr 2004 Trader Rating: (8)	I don't think the donut gasket will help because there's nothing to hold it on to the DP. The stock DP to catback connection uses spring bolts and that donut gasket. It's kind of like a ball and socket connection. The donut gasket is held onto the downpipe by a little lip. That lip is what's missing from the Helix flange. I dunno, I guess you could cram one in there but what I'm trying to say is that there's no bolts to hold in the gasket like the normal flange gaskets. I guess that's what the RTV is for?

04-27-2006, 06:05 AM	#8
kinger Professional STI Driver Car: 04 STI Fav Mod: Koni shocks Location: BFE Iowa Posts: 494 IWSTI Addict since: May 2004 Trader Rating: (1)	This was my reservation with the helix, the only way to make fit is get a midpipe like the madad where it will have the flat flange on it then go through a flex joint then gradually taper back to 2.5" to mate up with your axle back. You then have a 'stealthback' peiced together. That flat flanged connection will not work with the stock mid pipe no matter what you do.

04-27-2006, 09:16 AM	#9
Titleist71 Professional STI Racer Car: 05 PSM STi w/ custom Fav Mod: TiaL 38mm vented free as a bird. Location: Maine Posts: 622 IWSTI Addict since: Mar 2005 Trader Rating: (1)	well on one side the stock side the donut will seal. On the other side with the flat flange I would use RTV. You can get it napa. I used the gasket with my catback and it had a flat flange and I had no problems. Now I have a full TBE so I just have RTV to seal it. I have driven the car and have no problems with leaks.

04-27-2006, 10:11 AM	#10
RBMike The Next Petter Solberg Posts: 931 IWSTI Addict since: Oct 2004 Trader Rating: (0)	How long ago did you have it installed? I ask because I have the same setup & mine does NOT leak at all.

04-28-2006, 04:17 AM	#12
VetteVert Junior STI Driver Car: 05 Subaru WRX STi Fav Mod: Rally Armor! Location: Boone, NC Posts: 166 IWSTI Addict since: May 2003 Trader Rating: (0)	I had the same setup on my old WRX for 20k miles. No leaks. Did you use regular bolts, or reuse the spring bolts? You HAVE to use regular bolts to get a tight seal. What kind of gasket did you use? I used the ones provided by GRUPPE-S with the Helix downpipe. If you reused the stock gasket, try a new one. Helix has changed versions of their DPs so much I'm not sure where you have mount points, but on mine there was a mid-mount flange on the DP. The hole was oval and allowed for some adjustment. The proper mounting procedure for this type of DP is to hang it in place, install all DP -> Turbo bolts and torque (for a good seal), connect DP -> catback, and adjust mid-mount so that the flat plate of the DP is as flat as possible to the catback and torque the DP -> catback bolts. VV

04-28-2006, 07:18 AM	#13
RBMike The Next Petter Solberg Posts: 931 IWSTI Addict since: Oct 2004 Trader Rating: (0)	I did it exactly the way Vettevert discribes above. I used the gaskets & hardware that came with the DP.