Welcome to Ultimate Subaru Message Board, my lurker friend!
|Welcome to Ultimate Subaru Message Board, an unparalleled Subaru community full of the greatest Subaru gurus and modders on the planet! We offer technical information and discussion about all things Subaru, the best and most popular all wheel drive vehicles ever created.
We offer all this information for free to everyone, even lurkers like you! All we ask in return is that you sign up and give back some of what you get out - without our awesome registered users none of this would be possible! Plus, you get way more great stuff as a member! Lurk to lose, participate to WIN*!
* The joy of participation and being generally awesome constitutes winning
** Not an actual guarantee, but seriously, you probably won't regret it!
Serving the Subaru Community since May 18th, 1998!
Can you remove exhaust tin?
Posted 19 September 2003 - 02:20 PM
I have to remove the y and since this is a pain I figure I will just drop the entire exhaust and replace the gaskets 96k on em.
My Q is can I remove the exhaust tin reinstall the exhaust and be safe ?
Posted 19 September 2003 - 03:07 PM
By "tin", do you mean removing the heat shields? You don't have to remove the shields to get at the sensor, if you get a special socket (borrowed mine from AutoZone for free....)
Just out of curiosity, I tried to see if I could get the O2 sensor removed without dropping the Y-pipe. With the special socket, I got it loose, but I think i woulda broke something if I tried to remove it entirely. I was planning to drop the Y-pipe anyway, so I went ahead and did that.
I removed all the exhaust shields (loosened the bolts while they were on the car, 'cuz it took a LOT of torque). This wasn't necessary for the O2 sensor, but I wanted to check the condition of the cat/exhaust pipes. Mine is an '88, and the whole exhaust sytem back to the mid-pipe still looks like a baby (as long as I own my sub', I'm not moving to the east coast
Y'know, I didn't get a "donut gasket" for the mid-pipe joint (it's 1/2 inch think, looks like a lead ring). Normally I replace any gasket I take off, but I didn't know about that -- never took apart that part of the exhaust. I'll find out this weekend if the old one's still OK.
Posted 19 September 2003 - 03:08 PM
I disconnected the wye pipe from the heads, and dropped the whole system down far enough to remove the upper tin. Took some work with the heat wrench (torch) to get three of the tin bolts off, the rest broke off anyway. I used hose clamps and some sheet metal screws to reinstall the upper/lower tin pieces I removed from that junction.
You don't have to remove any other tin, just the pieces on that junction.
Be warned, though: three of the head studs came out of the head, instead of the nuts coming off the studs. And they dragged threads out with them. I had access to the correct helicoil set to repair them, but it was still a pain.
I detailed this at the end of this thread:
As to whether you have to reinstall it -- well, it's there to prevent starting a grass fire or trash fire, if you run over a plastic grocery bag it won't tend to instantly catch on fire if the heat shield tin is in place. It also has an almost negligible effect on cat light-off.
Posted 19 September 2003 - 03:20 PM
The heat shield above the cat is double-thickness, if you take off that one you'll fry your CV joint. The heat shield below the cat is heavy-duty single thickness, as it is you can still start a fire sittin' in a cornfield.
I wouldn't do it.....
The other section of shielding aft of the cat is kind of tied into the cat's heat shield (share the same bolts). So you'd have to rig somethin' up there, too. I suppose you could easily take off the downpipe shields -- but mine have a lot of dings from pebbles and road kill. Seems they're an extra protection for the exhaust pipe itself, as well as heat cladding.
Nope, I wouldn't do it....
Posted 19 September 2003 - 06:41 PM
I dont think I will remove the tin for good after reading the replies but I am going to reinforce the seams so I can get rid of this darn rattle problem during accel.
Posted 19 September 2003 - 07:03 PM
I don't think you have to disconnect the Y-pipe all the way just to get at the O2 sensor. You can unbolt the front studs (to cylinder heads) and center bracket and let it hang a bit. But if you're after a rattle, you might want to check all the heat shields. There were some parts of mine that were contacting the exhaust pipe itself. I could see 4 or 5 shiny metal contact points. I took a ball-peen hammer and put dents in the heat shields away from the exhaust pipe. It's 50/50 that they were actually causing a rattle, but it couldn't hurt.
'Course, to check all the heat shields you gotta drop the Y-pipe. Y-pipe's got 4 bolt-on points: the 2 front exhaust flanges (connects to each cylinder head), a center mounting bracket on the transaxle (4WD only?), and the joint at the back with the mid-pipe.
Each cylinder-head flange has 2 studs. Like Al said, these are likely to come out instead of just the nuts. He had 3 out of 4 come out; I had one. Easy enough to get a replacement stud (10mm x 1.25 x 40mm). The threads on my cylinder head were in good shape, but Al said he had problems....
The rear joint to the mid-pipe has two spring-loaded bolts. If the springs are really rusty, it's a good idea to replace them. This is where the "donut gasket" is. It's a spring-loaded fit lead ring, slips into the mid-pipe. Again, I don't know if it's good practice to replace that.
All these bolts (including the 24 heat shield bolts) were the toughest ones I've found on the car to get off. I soaked each in a good bath of PB Blaster overnight, and still needed a breaker bar and several layers of knuckle skin to get 'em off. If you're gonna take off the shields, remove the bolts on the car, 'cause I doubt you can get enough torque with your pipe laying loose on the floor.
So I replaced my O2 sensor, just 'cause 16 years seemed long enough. But the main reason I did this was to track down the rattle. I'll be running my wagon this weekend to see if it worked. I feel pretty confident that it was a rattling heat shield, or possibly a leaky gasket.
Posted 20 September 2003 - 12:46 AM
I had it up on a lift, and banged all the pipes pretty good with my fist, but didn't find the rattley one, so I guess it's time to get out the rubber mallet and do it again.
With the driver's window down, it sounds pretty darned loud when it resonates. It's just not been a very high priority to fix.
I probably could have gotten away with just replacing the head studs on two of the three that came out, but the third one might not have torqued up, and since I had the helicoil kit, and the inserts are cheap . . .
It I'dve been smart, I'd have heated up the head studs' nuts before trying to break them loose. I've got lots of air-cooled VWs and Corvairs in my background, I don't know why I didn't think to do that. Well, All's well that ends . . .
On the O2 sensor: the reference I have shows a sort of zee-shaped crowfoot wrench to remove it, without having to remove anything else. I have the O2 socket (basically a six-point 7/8" deep socket with a 1/2" wide slot up the side for the wire) and it won't fit over the OEM O2 sensor -- the body of the sensor is too wide. It worked fine for the replacement O2 sensor (Borg Warner), though. I definitely had to remove the upper junction heat shield to use a wrench on the old O2 sensor.
Posted 20 September 2003 - 04:23 AM
Posted 20 September 2003 - 04:26 AM
Posted 20 September 2003 - 10:48 AM
Rattly cat: yeah, mine might be that, I didn't hit it very hard with my hand when I was checking, but a rubber mallet will show it for sure. I'll get under it later today and see. Good idea, thanks.
Posted 22 September 2003 - 02:17 PM
I've been chasing an exhaust rattle for a couple of months -- it's exactly as Al describes: only when HOT, and only at 2000-2200 RPM. It was hard to narrow down, because at first it only happened when moving and decelerating. But it's gradually been getting more frequent, and now I can reproduce it at curbside when I rev it up to 2200 RPM.
I did a lot of pounding with fists and/or rubber mallets, but never found anything. Didn't surprise me, cuz when I did this, the pipes were cold (or at least, not as hot as necessary). Actually, I did find the center bracket on the Y-pipe broken, so the pipe was hanging by front and back mounting points only. It was easy to believe that this stressed the pipe and caused the heat shield to rattle.
But I proved to myself this weekend that that wasn't the case. Last week I dropped the Y-pipe, put in new gaskets and checked all the heat shielding (see postings above......) Same rattle, same sound, same pitch, same conditions.
Early on, I put a microphone under the hood and hooked it into my stereo. (Not a good substitute for the Dooby Brothers, but it gives a renewed appreciation for the workings of the engine compartment...) Then I drove around the neighborhood 20 times, each time changing the location of the microphone. The rattle was loudest near the exhaust and cat converter.
When I could finally reproduce it at curbside, I used a stethoscope and verified it came from the exhaust. But I still believed it was the heat shields causing a rattle. Until this past weekend.
Now I'm ready to buy into the "rattling catalytic converter" theory. In fact, I'm convinced!!!
Obviously the fix is to get a new Y-pipe. $$$$$$$ ! Can a muffler shop weld in a generic replacement for the cat? Or how about this: some strategic dents in the cat casing to "squeeze" the honeycomb back into submission? Or sinking a coupla sheet metal screws through the casing into the honeycomb material, then seal up the screw heads? I live in an emissions-testing area, so I don't have the option of gutting the cat.
Any ideas (other than $$$$$$) ?
Al, let me know what you find and do to fix it.
Posted 24 September 2003 - 11:26 PM
Tomorrow at noontime, I pick up a complete TBI assy for testing purposes. It's good to have a friend at a Subaru wrecking yard
After I get it back together, I'll try to localize my rattle -- the last couple of days I drove it (Mon/Tue), I could not get it to rattle very much at all. But I guess I could try harder.
I thought that the wye pipe (with the funky junction where the O2 sensor mounts) is a simple wye -- is there catalyst material in it? If so, I can't imagine trying to fab one using a generic cat. I was thinking that it might be the "actual" catalyst rattling, the one on the pipe to the rear of the wye pipe. That one's a catalyst for certain.
I have tried to "squeeze" a noisy cat in the past, unsuccessfully. It wasn't a Subaru cat, though. Through-bolting with a long bolt might shut it up, but it definitely won't catalyze nearly as well afterward.
I had access to an '86 Sedan Turbo today, MPFI, and his headpipe is bad -- this is not the crossover, but the pipe off the turbo to the rest of the exhaust. I called the dealer, turns out this pipe contains a precatalyst, and cost is over $600! Yow!
He's gonna get one from a 'yard. I don't blame him.
(This Turbo's fuel pressure regulator has vacuum on it at idle just fine. Of course, the whole setup is completely different from my SPFI, but the principle is the same. Until I can find better info or see a working vacuum routing setup, I can only guess.)
0 user(s) are reading this topic
0 members, 0 guests, 0 anonymous users