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Small Exhaust Leak @Spring Joint w/New Gasket?!
Posted 09 June 2009 - 11:58 PM
when parts of the original joint gasket fell out. 1991 Legacy L wgn, auto.
(Thanks to a prior poster for the image of what/where:
I got new parts from Advance Auto -- bolts, nuts, springs, and gasket.
With a friend's help, we cut off the old bolts (Dremel) and installed the
new gasket (which is conical, looking like someone soaked a brillo pad
in zinc or ...); but it leaked. The bolts can be tightened only so far
--the threaded end just clears the nut, and the thicker shaft snugs
up to the plate. (I should remark: the old bolts had the same size
EXCEPT for having longer threaded ends -- which would make starting
the tightening easier (we used tools to bring the pipes close enough)
--; the thick part abutting the plate to the broad flat part compressing
the spring is same length.) (I neglected to compare springs; the old
ones I see are now as long as the thick/unthreaded part of the bolt.)
Well, we added first one, then a 2nd washer (thin: 2mm@?). But
at the end of the day (and it was that), there remained a small,
felt w/one finger, leak. Quite quiet and all, but he doubts that the
emissions tester will think so, or the testor will detect something.
Are these gaskets such that with some use --vibration, continued
spring compression, heat-- , the rear/cat-side pipe will press ever
more into the gasket and finally, completely seal?
My sense is that there is a side --and it must be of the gasket,
for it shifted between our efforts (1 washer, than 2nd)-- from
which the leak comes; i.e., one could mark the gasket at the
point, and then *aim* it by rotating the gasket (when loose).
So, some imperfect match of roundness of pipe & gasket
I suppose we could try adding yet a greater washer thickness,
so that upon tightening, the springs would be even more compressed.
But pulling in two broad surfaces that imperfectly match seems to
be something that could resist considerable force, at least initially.
Posted 10 June 2009 - 07:15 AM
can't have an uneven surface here or it will leak
Posted 10 June 2009 - 07:47 AM
The local exhaust bending place fixes these for 40 bucks. Almost what I have in parts especially when I need to buy those goofy clamps to mimic a flange.
They cup off both pipes and weld a new piece in - maybe 6 inches. I do this after all work has been done on the car. Lets face it these joints are wimpy. Even if you fix it now within a few years the exact same problem is likely.
On the rare occasions that I do just put a new donut in there (I'm working on 95-99's) Walker does make a slightly larger donut that I find works better than the one listed that is often too tight (although I always start with the listed donut to try). The generic hardware kits with springs are useless. If you'd like some factory springs and can wait a few days and pay for shipping plus a couple of bucks I can send you some (again off 95-99's). PM me.
Posted 10 June 2009 - 09:45 AM
Posted 10 June 2009 - 10:25 AM
I had used an Autozone flange repair so the subaru bolts weren't the right length at all.
Posted 10 June 2009 - 01:41 PM
--i.e., one can see rusty imperfections, but how much sanding/etc.
did you do to that, or is that the workable state (really rough & loose
stuff gone) ?!
(I confess to having not given much thought to this, but recall that
I don't think my pipes were much worse really.)
ALSO, again, it seems as though my leak has a direction, which I
think is related to the **gasket** --rust, OTOH, is fixed in place on
the pipes. So, that suggests some imperfect roundness, IMHO.
(i.e., again, the gasket I think rotated some between initial install
and re-installs w/added washers; the direction (& volume) of leak
Davebugs, thanks; I'll keep your kind offer in mind. I do have time
(emissions test due August). So, you find the non-Sub. parts to have
inferior springs, insufficient tension? --not redressable by washers?
(Though, as I noted, given the short threaded part of the replacement
bolts --JUST enough to go through length of nut, really zilch beyond(!!)--,
increasing the compression will entail some added effort/technique to
bring pipes close enough to get a fair start threading the nut (after
which there is only so far to tighten_.)
I'm also remarking at the different appearances of the gaskets -- what
PP73 shows being quite *meshy*, and the Advance being more *solid*,
BTW, my buddy suggested trying one thought I had about inverting
the gasket, as that would put its thicker side towards the Cat-pipe's
concave compressing edge; but re-thinking that I figured it would
also quickly compress & CRUMPLE the gasket into pieces!
(and that WWII bomber airplane sound would come again)
I'll go check the Advance springs to get some idea of their coil
vis-a-vis the Sub ones (which had ends overlapping about 1/4"
and 5 full turns/coils between).
Will have to give a little chance to seeing the gasket get compressed
into a complete seal. --my preferred repair method, wishful thinking.
Posted 10 June 2009 - 01:46 PM
Posted 10 June 2009 - 02:06 PM
I bought the car used, so I assume it did not come from the factory that way.
Posted 10 June 2009 - 02:50 PM
Looks like you had a camshaft to seal and a starter that needed contacts as well.
[...]Here's my pics from when I had this issue '00obw
Posted 10 June 2009 - 04:13 PM
Posted 10 June 2009 - 04:54 PM
Posted 10 June 2009 - 06:47 PM
hehe yah when I was taking pics of the exhaust parts the o-rings and starter contacts were making a big fuss about being left out so I let them be in the pic too.
I only mentioned it because I thought someone might think there was a trick to sealing a leaky exhaust connection using those parts.
Posted 10 June 2009 - 07:10 PM
Posted 11 June 2009 - 12:26 AM
Nice, er, *belt* you put on the waist. I just marveled that mine was holding
up sans the two bolts (both corners) at that end, and will have to look into
doing some rigging of some sort I guess.
Posted 11 June 2009 - 09:24 AM
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