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#3290466 - 07/19/16 01:39 PM Cat to y/h pipe bolts and gasket
Former85Owner Offline
Climber

Registered: 12/30/12
Posts: 520
Loc: Albany, NY
The car is so reliable I don't even have to come here!
Anyway...i noticed a small exhaust leak.

I'm wondering if the bolts there are threaded into the flange from the factory or just a simple nut and bolt setup. This is the joint under the seats, as described in the title.

The nuts are pretty much gone, I went thru something similar with an explorer. In that case the bolts were attached to the cat assembly, but when the nuts were chiseled away you just separate. Was easy though because the whole exhaust was out.

It is hard to tell from the rust, and knowing this could make life easier. The dealer tech i talked to in the parts dept when I bought the gasket told me to wirebrush it, spray the crap out of it with penetrating oil (a few times the day before) and in the morning apply some heat, penetrant, lock vice grips and rotate, and gently tap the bolt until it moves. Told me to use acetone/atf. He said they have an unlimited supply from flushes, and to always save yours for that. Acetone is cheap in family dollar(nail polish remover). In the shop they have aceteleyne.

Don't hit to hard because the flange could be brittle. He said he is pretty sure it is NOT threaded, but they don't get many of those for exhaust. The manifold studs are another story, those need high heat and vice grips.


Edited by Former85Owner (07/19/16 01:47 PM)
_________________________
98 MGM LS, Tan, Fully loaded but Non HPP (Original Owner didn't like the ride frown ). 177K miles. Dorman Intake, KYB Gas Adjust. Added: Heated Seats, Heated Mirrors, voice visor Homelink, 02B02 fuel tank shield

Former: 85 White Box, 205K miles, Jumped time. RIP 8/8/2000.

Allergic to Car Payments

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#3290634 - 07/19/16 02:21 PM Re: Cat to y/h pipe bolts and gasket [Re: Former85Owner]
IPreferDIY Offline
Over the Hill

Registered: 05/12/15
Posts: 1082
Loc: Canada
The fordparts.com site shows separate bolts and nuts. On mine, the nuts had rotted off, but the bolts were pretty much welded to the H-pipe flanges. I didn't know any better, so I just pounded them with a BFH. This didn't help the flanges, but they're still functional. Hopefully I'll think of a torch next time I'm in such a situation.


Attachments
ExhaustFasteners.jpg


_________________________
2000 Grand Marquis LS HPP, a hand-me-down in 2008 with 128,000 km; 180,000 km as of May 2015
mods: air filter box 'tuba', headlight relay harness, J-mod (around 186,350 km), 70mm throttle body, KYB Gas-A-Just shocks, aluminum driveshaft, ARA3 PCM

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#3290666 - 07/19/16 02:23 PM Re: Cat to y/h pipe bolts and gasket [Re: Former85Owner]
Former85Owner Offline
Climber

Registered: 12/30/12
Posts: 520
Loc: Albany, NY
Thanks!

Yeah, looks like a simple nut and bolt, bad but better than being threaded!

The flange don't look too healthy, so I'll try to go easy on it.


Edited by Former85Owner (07/19/16 02:24 PM)
_________________________
98 MGM LS, Tan, Fully loaded but Non HPP (Original Owner didn't like the ride frown ). 177K miles. Dorman Intake, KYB Gas Adjust. Added: Heated Seats, Heated Mirrors, voice visor Homelink, 02B02 fuel tank shield

Former: 85 White Box, 205K miles, Jumped time. RIP 8/8/2000.

Allergic to Car Payments

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#3290794 - 07/19/16 03:00 PM Re: Cat to y/h pipe bolts and gasket [Re: Former85Owner]
Former85Owner Offline
Climber

Registered: 12/30/12
Posts: 520
Loc: Albany, NY
Oh, and one more lesson learned - no aftermarket exhaust gaskets. I bought a walker one for the explorer and it was gone after a few hundred miles. Completely delaminated and leaking. At least Rockauto refunded the product.

The ironic thing is the Ford one can be had cheaper in both cases! The crown vic one can be had for under $10 from Ford, shipped if you shop around. I always check Ford from Ebay dealers, they are extremely competitive with aftermarket. Sometimes less, sometimes a bit more. Parts never let you down though.


Edited by Former85Owner (07/19/16 03:02 PM)
_________________________
98 MGM LS, Tan, Fully loaded but Non HPP (Original Owner didn't like the ride frown ). 177K miles. Dorman Intake, KYB Gas Adjust. Added: Heated Seats, Heated Mirrors, voice visor Homelink, 02B02 fuel tank shield

Former: 85 White Box, 205K miles, Jumped time. RIP 8/8/2000.

Allergic to Car Payments

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#3290858 - 07/19/16 03:15 PM Re: Cat to y/h pipe bolts and gasket [Re: Former85Owner]
IPreferDIY Offline
Over the Hill

Registered: 05/12/15
Posts: 1082
Loc: Canada
That reminds me, you should check the mating of the flanges before installing the gaskets. When I took off the exhaust dampers relatively recently, I found that the ears on the flanges were bent enough to create big gaps. I filed them down enough to make the gaps between the bare flanges smaller than the thickness of the gaskets. Apparently the next step would be having new flanges welded on.
_________________________
2000 Grand Marquis LS HPP, a hand-me-down in 2008 with 128,000 km; 180,000 km as of May 2015
mods: air filter box 'tuba', headlight relay harness, J-mod (around 186,350 km), 70mm throttle body, KYB Gas-A-Just shocks, aluminum driveshaft, ARA3 PCM

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#3291546 - 07/19/16 09:28 PM Re: Cat to y/h pipe bolts and gasket [Re: Former85Owner]
2468 Offline
Over the Hill

Registered: 10/19/13
Posts: 1264
Loc: Argo Nunya
Originally Posted By Former85Owner
I'm wondering if the bolts there are threaded into the flange from the factory or just a simple nut and bolt setup.


Originally Posted By IPreferDIY
I found that the ears on the flanges were bent enough to create big gaps.


I'm not sure if '98 flanges/bolts same as my car's. The factory pipes are still on my '92, & the flange/bolt set-up was similar to diagram above. Bolts should thread into the flange, but they might be so galled, C4 probably won't loosen them.

If really bad, you could try what I did...

Dampeners hung by a thread, so I removed them. I cut heads off the flange bolts & bolt ends protruding other side with Dremel/cutting wheel. Drilled bolts out with several co'balt bits.

Flanges were stuck together good & there were still some sections of bolts holding flanges together. Used Dremel/cutting wheel slicing into gap, separating flanges.

Before reassembly, drilled thru holes again to remove any bits of bolt that didn't get drilled out first time. Some of this was difficult, & had to use assortment of Dremel cutting bits, some diamond-tipped. Removed burrs around holes. Used drill w/fine wire brush on mating surfaces.

Mating it together, there was a gap between the flanges from warpage.

Used 4 flange gaskets on each pipe (AZone 60924), 'glued' together with Loctite RTV 5920 Copper, letting cure 48 hrs before install. Used one exhaust flange seal ring at each pipe connection, of appropriate size, that fits vintage British MGB cars. Applied Loctite 5920 to flange mating surfaces at assembly.

Used four each: gr-5 3/8-24 x 1-3/4 bolts with 10mm flat washers at the head, & 3/8 lockwashers & 3/8-24 nuts, to secure. Anti-seize on threads.

I let Loctite 5920 on the mating surfaces cure 48 hrs.
_________________________
Current Fleet: '42 Indian (14 yrs); '92 HD (26 yrs); '73 2X-Y17 W53-5.7L (13 yrs); '84 1G4-A-H19-3.0L (20 yrs); '87 2G3-G-R47-5.0L (27 yrs); '92 2FA-72-4.6L Police SO/LPO (21 yrs); '02 SAJ-03-4.0L (4 yrs); '04 2T-E-1.8L (14 yrs)

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#3291706 - 07/19/16 10:45 PM Re: Cat to y/h pipe bolts and gasket [Re: Former85Owner]
BigMerc96 Offline

I know nothing
Posting Addict

Registered: 06/05/10
Posts: 19868
Loc: I can see Detroit from here!
^^When mine rotted apart, the flanges were simply removed and a sleeve put in their place. Could probably accomplish the same thing with an appropriately sized band clamp.
_________________________
-Steve

2006 Audi A6 ~132k miles, stock.
1998 Mercury Grand Marquis LS HPP ~100k miles, slowly acquiring modifications.
1997 Town Car Cartier ~145k miles, Ported Plenum, Gutted Airbox, Contour E-fan Retrofit, Dual exhaust with Magnaflows, cats deleted, MSD Ignition, KYB Gas-A-Justs, P71 front bar, air ride reinstated, Projector retrofit, Caddy 4-note horn retrofit, Wood rim steering wheel retrofit, holistic weight reduction as the parts fall off..
1996 Mercury Grand Marquis GS 117,485mi. R.I.P. 7/14/12 frown

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#3292026 - 07/20/16 09:06 AM Re: Cat to y/h pipe bolts and gasket [Re: Former85Owner]
Former85Owner Offline
Climber

Registered: 12/30/12
Posts: 520
Loc: Albany, NY
I wonder why ford mentions FLAG HEAD BOLTS. Usually there is no threading when you have a flag (would be impossible to install, no?). Wondering if the rust jacking was so bad that it held stronger than a thread. Heat and penetrating oil would/should/maybe take care of that.

My nuts are already 95% gone, won't take much to spread things. Same story with the Explorer. Rust was holding it together. One tap with air hammer took it apart, I already see a gap on the marquis. I can spread it a bit and easily cut the bolts with a wheel, if they won't come out.

I have two other options, obviously not looking for a show car here:
The flanges look straight now, and extreme measures will definitely destroy them. If I bring it in I know its it is going to be at least $200 for something stupid like this. I asked in one place he looked at it and they said the flanges are going to get destroyed, and that means an entire 1800 exhaust system (they claim they can't legally patch cat converters, uh, huh). He said you know what to do with it on your own...we talked about options.

- drill new holes on the flange. Should be easy to go thru the flange.
Bolts are 5/16 according to Ford, more than enough.

-Get this: http://shop.advanceautoparts.com/p/walker-flange-repair-kit-fits-2-od-pipe-36132/26010005-P

I've used it on other cars, works absolutely great. I put anti-sieze under it so it don't rot away. Not cheap, but the alternative could be hours under the car. Advance has good discounts so about 30-35 or so for the pair.
_________________________
98 MGM LS, Tan, Fully loaded but Non HPP (Original Owner didn't like the ride frown ). 177K miles. Dorman Intake, KYB Gas Adjust. Added: Heated Seats, Heated Mirrors, voice visor Homelink, 02B02 fuel tank shield

Former: 85 White Box, 205K miles, Jumped time. RIP 8/8/2000.

Allergic to Car Payments

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#3301962 - 07/29/16 09:05 PM Re: Cat to y/h pipe bolts and gasket [Re: Former85Owner]
Former85Owner Offline
Climber

Registered: 12/30/12
Posts: 520
Loc: Albany, NY
If anyone attempts this repair this is what is involved:

I Did it and saved the flanges.
Bolts are definitely not threaded.

Used combinations of:
Propane heat to heat the flange (too lazy to get mapp, since its not threaded it is fine, also you don't want to get too hot, its not a thick flange).
Candles to run wax into the gaps(could be helpful)
Locking pliers
Air impacting hammer (probably the best tool, breaks up what is left of the nut, seperates the flanges and cracks the base of the bolt where its rust welded to the flange)


Took about 40 minutes to do all 4 and install the new Gasket. I was being gentle not to hurt the flange.

Replaced with black coated flanged 3/8*16*1.25 (or so) grade 8 hardware from (a well stocked ACE hardware store- not all carry the flanged stuff). There are also matching crushed lock nuts. A bit of anti-seize(hopefully never to be needed!) and its as good as new.


Edited by Former85Owner (07/29/16 09:06 PM)
_________________________
98 MGM LS, Tan, Fully loaded but Non HPP (Original Owner didn't like the ride frown ). 177K miles. Dorman Intake, KYB Gas Adjust. Added: Heated Seats, Heated Mirrors, voice visor Homelink, 02B02 fuel tank shield

Former: 85 White Box, 205K miles, Jumped time. RIP 8/8/2000.

Allergic to Car Payments

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#3303362 - 07/30/16 10:45 PM Re: Cat to y/h pipe bolts and gasket [Re: Former85Owner]
PHoganDive Offline
Over the Hill

Registered: 06/11/11
Posts: 3078
Loc: Mass, USA
Originally Posted By Former85Owner
If anyone attempts this repair this is what is involved:

I Did it and saved the flanges.
Bolts are definitely not threaded.

Used combinations of:
Propane heat to heat the flange (too lazy to get mapp, since its not threaded it is fine, also you don't want to get too hot, its not a thick flange).
Candles to run wax into the gaps(could be helpful)
Locking pliers
Air impacting hammer (probably the best tool, breaks up what is left of the nut, seperates the flanges and cracks the base of the bolt where its rust welded to the flange)

I don't understand the function of the candles/wax. That spot sees red hot exhaust coming out of the catalytic converters. The lifetime of any wax used there would be measured in seconds (maybe minutes) after starting the motor.
_________________________

2006 CVPI w/120K, J-Mod, MSD COPs, BOC Tune, American Muscle Wheels, Magnaflow Stainless Catback Duals, 35% tint, UltraGuage, headlight relay harness installed w/ 80/100 watt bulbs.

1996 GMQ 116K miles, Bilstein shocks, otherwise stock (Retired 7/2011)

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#3304058 - 07/31/16 01:53 PM Re: Cat to y/h pipe bolts and gasket [Re: PHoganDive]
IPreferDIY Offline
Over the Hill

Registered: 05/12/15
Posts: 1082
Loc: Canada
Originally Posted By PHoganDive
I don't understand the function of the candles/wax. ...

Based on what I've read about it, the wax takes the place of penetrating oil when dealing with stuff that's being heated.
_________________________
2000 Grand Marquis LS HPP, a hand-me-down in 2008 with 128,000 km; 180,000 km as of May 2015
mods: air filter box 'tuba', headlight relay harness, J-mod (around 186,350 km), 70mm throttle body, KYB Gas-A-Just shocks, aluminum driveshaft, ARA3 PCM

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#3305210 - 08/01/16 03:42 PM Re: Cat to y/h pipe bolts and gasket [Re: PHoganDive]
Former85Owner Offline
Climber

Registered: 12/30/12
Posts: 520
Loc: Albany, NY
Yes, IpreferDIY is correct.

Once it is heated, there is a millionth of an inch gateway... the wax instantly wicks into the joint with capillary action. Any liquid penetrant will burn off immediately from such intense heat. The guy at Ford told me he never broke off any studs using that technique. On the last one I had the vicegrip and tried to move it after heating...it was extremely difficult. Then I put in the wax and just touching the tool made the stud move. Again this isn't threaded, but it would obviously help even more with threads.
_________________________
98 MGM LS, Tan, Fully loaded but Non HPP (Original Owner didn't like the ride frown ). 177K miles. Dorman Intake, KYB Gas Adjust. Added: Heated Seats, Heated Mirrors, voice visor Homelink, 02B02 fuel tank shield

Former: 85 White Box, 205K miles, Jumped time. RIP 8/8/2000.

Allergic to Car Payments

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