Having removed my Y pipe off of my 92 loyale to fix a leak, I now have a small leak where the right side of the Y pipe bolts up to the exhaust port on the cylinder head. I've tried with and without the gasket. If I tighten up the bolts any more, I'm affraid I'll strip the threads in the aluminum head. I've already cleaned up those threads with a tap and die (10mmX125).

I HAVE 2 QUESTIONS

 

1) There are 4 threaded holes where the exhaust flange bolts to the head. Only 2 are used. Are the other 2 same size holes for a replacment Y/Cat pipe, with subaru knowing that the threads get "bougered" up when unbolting? Is the flange on a replacement Y/cat pipe not welded to the pipe so that thses "new" holes can be used?

 

2) has that flange been known to warp over time? I have 160000 miles on it.

 

 

My original problem was resolved but now I question removing the pipe

If I tighten up the bolts any more

 

No bolts, studs and nuts, now you know why.

 

has that flange been known to warp over time?

 

Well no, a flange sitting on a shelf does not warp all by itself, only when tightened does it tend to warp, or "distort", as it gets pulled by the fastners. Easy enough to "tune" with a hammer/and/or/file. If old enough the rust will have eaten it away to the point where it is a shadow of it's former self, easily warped/distorted.

 

I question removing the pipe

 

So do I, especially when welding/heating on it, to fix it, without clamping it so it won't move.

Did you use an OEM gasket? If not, buy a set and try that first. Some of the cheap ones are worthless.

No not OEM, but just the same quality looking. A metal ring of some type is incoperated into the gasket. I dont recall any gaskets when I first removed the Y pipe. I know it wont warp sitting on shelf, My question related to the heat/cool cycle over 15 years and then removing the pipe from the car. YES there is a bit of rust at that area of the pipe. It wont pass inspection and let alone the dangers of being stuck in traffic this winter with the windows up. You have me leaning towards a new Y/cat pipe. DOES anyone know if a new Y pipe from Subaru will utilise the other threaded holes I've refered to?

you could have new flanges welded onto your existing y pipe at an exhaust shop that would use the unused holes, you could try wrapping your gaskets around with aluminum foil a couple of times.. you could try to get some studs and nuts, and set the studs in there tight and THEN try tightening down onto the studs.. or you could just see how bad life is with the windows rolled up. My exhaust leaks pretty bad, AND the body of my car looks like swiss cheese (search my name and "rust" and youre bound to find pics) and I never smell exhaust fumes... granted, CO has no odor, but the rest of them sure do. Obviously I live in a non emissions area, and you may be in a different situation... but thats my two bits.

Here in NJ they are go/no-go on emmisions. Pass or no-pass. With no-pass and it's passed your inspection date, no drive leagaly till fixed. I have untill June 08 to resolve this leak. But I think I'll call or stop by my closest Subaru dealer parts in Cherry Hill nj this Monday and see what he says as to my flange orentation question.

I'm leary of removing the Y/cat pipe again because I KNOW one of those holes threads are shot. I would have to install a larger stud/bolt, re-tap and prob drill flange larger also.

Don't use bolts, use studs. The stud will get all the threads in the hole, a bolt can't - unless you custom cut it to legth, or get very lucky.

 

I had a Y pipe that was a bit distorted - the flanges were not in the same plane. It would never stay sealed, one gasket would eventually fail. Put a Y pipe with good geometry on, with NAPA gaskets, no problems.

 

The "extra" holes are there because the head can be used on either side of the engine. I have never seen any pipe OEM or aftermarket that used the "other" holes. You could customize one, but helicoils would be easier.

Don't use bolts, use studs.

 

 

SORRY Just to clarify, I was saying bolts, but picturing what came off, studs

 

 

I'd use just what came out............studs, be they originals or new ones from subaru

Don't worry about boogering the holes... you can retap them to a fine thread 7/16 w/o redrilling. With out even dropping the y pipe actually. Mine is still holding tight. That repair option still leaves you with the next step option of redrilling and inserting a proper helicoil. Thats for next time you remove the threads!