Exhaust leak? or my imagination?
#1
Exhaust leak? or my imagination?
So my car has been garaged for a while, started a little, driven mabye 15 miles and that was yesterday. I havent washed it, so yes I know it is dirty. But I noticed this evening while investigating a boost leak that there was suit like exhaust gas all over my valve cover, just in one spot. Like it shot up from the manifold or o2 housing area. But the suit is only on the valve cover, and the exhaust checks good. Its also blowing out my hood vent apparently.
Your thoughts?? Recently I changed my downpipe to the QTP, I dont see how it would blow back straight up if that were it though. Any ideas, its late.
I already wiped it off the valve cover, but you can see where it was, only on the front and top, and only right over the manifold...
Could be my imagination, and its just dirty though.....
thanks
Your thoughts?? Recently I changed my downpipe to the QTP, I dont see how it would blow back straight up if that were it though. Any ideas, its late.
I already wiped it off the valve cover, but you can see where it was, only on the front and top, and only right over the manifold...
Could be my imagination, and its just dirty though.....
thanks
#4
I cant see it being the manifold, everything on the top-side of it looks clean, seems like it came from the front of the car (impossible) or straight up from under the manifold but its all clean down there. I dont see how it could blow straight up from a downpipe seated incorrectly. I think I will clean it and see if it happens again, might just be dirt buildup, my cutout was leaking until yesterday, mabye some gasses found their way up front?(doubt) any more suggestions guys?
#6
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check out this link, and read his fix for it in post #21 https://www.evolutionm.net/forums/sh...e+exhaust+leak is his picture of the soot on the valve cover similar to yours before you cleaned it off?
the reason the soot is on the front of the valve cover is while you are driving, the air is moving over the hood vent and pulling heat out of the engine bay (cool air enters through the front bumper). if the downpipe is leaking, the soot will be pulled up the engine bay (some collecting on the valve cover) and out of the hood vent.
the reason the soot is on the front of the valve cover is while you are driving, the air is moving over the hood vent and pulling heat out of the engine bay (cool air enters through the front bumper). if the downpipe is leaking, the soot will be pulled up the engine bay (some collecting on the valve cover) and out of the hood vent.
Last edited by evo150; Feb 6, 2008 at 11:40 PM.
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while you are re-installing the downpipe, check for more signs of soot coming from between the downpipe/o2 housing (just to verify this is the problem). what type of gasket/bolts does the QTP downpipe use?
#10
Its the standard type donut gasket, just very large in size to accomodate the 3" DP. Do you think putting a very light bead of red-rtv on the gasket would help some? I might try that.
Oh the bolts, are sort of this T shaped machined piece with a threaded bolt that slides through the middle to the O2 housing. Not really positive why this method is used, but it seems pretty common. Mabye Im an idiot and have them installed wrong lol.
Oh the bolts, are sort of this T shaped machined piece with a threaded bolt that slides through the middle to the O2 housing. Not really positive why this method is used, but it seems pretty common. Mabye Im an idiot and have them installed wrong lol.
Last edited by Jameson_IXMR; Feb 7, 2008 at 12:13 AM.
#12
Any idea the torque value off hand? I was provided with a generic instruction manual that had nothing pertaining to an evo in it.
Still not sure how the gasses come back up exactly, unless you mean that the gasses leave soot down there and the air brings it up.
??????
Still not sure how the gasses come back up exactly, unless you mean that the gasses leave soot down there and the air brings it up.
??????
Last edited by Jameson_IXMR; Feb 7, 2008 at 12:41 AM.
#13
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as you are driving air is flowing over the hood vent "pulling" hot air out of the engine bay. at the same time, if you have a exhaust leak(downpipe to o2 housing, manifold,etc) the exhaust gasses are being pulled up as well. ill see if i can find the link that explains this better than i can.
downpipe bolts should be torqued to 37 ft lbs
edit: link that talks about the hood vent https://www.evolutionm.net/forums/sh...nt+pulling+air
downpipe bolts should be torqued to 37 ft lbs
edit: link that talks about the hood vent https://www.evolutionm.net/forums/sh...nt+pulling+air
Last edited by evo150; Feb 7, 2008 at 12:59 AM.
#14
Oh nono, I get it, its the ventrilli principal. Like how siphoning gas with a hose works. I appreciate all of the help, mind if I ask where you found that torque value? Are those for the factory spring bolts? I have the tech manual, but the torque value would be different between the two bolt types for certain. I guess Ill figure it out in the morning...
Thanks
Thanks
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the torque value i gave you is for the stock spring bolts (from evo service manual). i would contact qtp and see what they suggest to torque them to.
be sure to keep us updated. hopefully its a simple fix
be sure to keep us updated. hopefully its a simple fix