Need Exhaust Advice

[Bwana Bob]

Well, I need a new exhaust (cat back) for the Explorer. When the OEM system fell apart, I put in a Borla stainless steel system. It lasted many years until the muffler finally burned out internally. I never really liked it, though, because it had no resonator and therefore was noisy at certain speeds. Five years ago, in 2009, I put in a Walker OEM style system from Advance Auto Parts, which was nice and quiet, but it rusted out and fell apart last week. The Walker components may have a lifetime warranty. I'm going to check with Advance today.

I've been looking around for another stainless system, but the only kit I can find that would fit is a Gibson exhaust, which also has no resonator. I don't want to spend $300+ for another booming/droning exhaust. Here is the Gibson system:
http://gibsonperformance.com/products/retail_prod_annoucement.php?product_number=619677

I did find an aftermarket resonator: http://vibrantperformance.com/catalog/index.php?cPath=1022_1033_1055

I'm not really keen on doing a science project, but adding a resonator to an existing kit doesn't sound too difficult.

Any ideas or experiences? What make sense, stay with OEM style and resign myself to replacing it every 5 years, spend more to get a system that may outlast the vehicle (she's 22 years old), and probably have to modify to get the noise to an acceptable level?

Thanks.

Bob

 

[Anime]

You should have kept the Borla system. Their entire SYSTEM carries a lifetime warranty. I called Borla back when they were discontinuing the systems for the first gen, and asked about this. Their response was that although they would no longer be producing them for sale, they keep ALL of the manufacturing specs and can make a one-off replacement for a customer with a warranty claim. Either that or they would offer a complete refund to a customer if there was some issue or the customer didn't want the replacement.

The Walker Quiet-Flow 3 mufflers do carry a lifetime replacement warranty. Their other cheaper SoundFX mufflers do not. I'd say the Quiet-Flow is one of the best mufflers and systems in terms of fit and sound, if you don't want ANY drone. The design of the 91-92 Explorer mufflers is such that the Quiet-Flow mufflers actually flow pretty good.

The upgrade to the Quiet-Flow would be a Dynomax Super Turbo 17747. It flows better and would be slightly louder, giving a deep, low growl. There IS some drone at certain speeds, but a resonator would take care of that. Walker used to make the rear pipe for the 91-92 Explorer with the resonator included, but they've apparently discontinued the pipe but offer the resonator by itself, as part number 44206. The product images for the resonator still show the entire rear pipe.

You could also try the Dynomax Super Turbo 17731. This is a shorter muffler, closer to the size of the one in the Borla system, and is an in-store product at Advance Auto Parts (although you should buy online for store pickup and use a $20 off $50 coupon to save some $$$ if you get one). You'd need to use a straight pipe to fill in the extra length compared to the 17747. The reason I offer this suggestion is the shorter muffler might actually reduce the drone, since part of the reason for the drone is how much more the longer muffler flows than the 4.0L needs. There was a post years back where a member put on a 17731 instead of the 17747, and said there was NO drone.

Adding to the list of options, you can also get Dynomax's Ultra-Flo stainless steel mufflers. They don't offer stainless steel pipes, but you can get 403 stainless custom bent at a lot of exhaust shops.

It's worth noting that Dynomax also offers their VT series mufflers that have an internal valve to eliminate drone. The mufflers are stainless and also have a lifetime warranty, so this might be a good route to go if you hate drone and want the flow of a straight-through muffler, but don't want to deal with the hassle and expense of installing a resonator.

The Dynomax mufflers DO rust out, but with the lifetime warranty, I have found it is still worth it, since you just replace the muffler and trade it in for a new one every so often. Even their stainless steel versions will probably blow out like the Borla since they use fiberglass. No muffler lasts forever, manufacturers generally work on the assumption most people will sell their vehicle and get something else long before the muffler wears out and will need a warranty replacement.

As for the Gibson, I had one of those. The first thing I noticed was the fit was terrible. Though I was modifying a 4-door system to fit a 2-door (which was just a matter of shortening the middle pipe), nothing I did would get the rear pipe to fit how it should. The rear pipe was in two pieces, and there was just no position in which it didn't hit the shock or the frame. Their newer systems may have since been redesigned and fit better, but in my experience, I was not impressed. The pipes are also 2.5" instead of 2.25", as is the muffler. The muffler is a round cannister instead of an oval, and is pretty much a giant glasspack. The muffler has internal louvres (which disrupt air flow), and so really isn't that great. I did finally manage to bungle it on good enough to take it for a test spin, and the sound was "ratty". There was not only a constant, low, drone, but the ratty cackle on acceleration and deceleration that comes with big pipes. Between the poor fit, large size, and the undesireable sound, I removed it and sold it, replacing it with a Walker system until I switched to the Dynomax.

Note I am using the Dynomax 17747 with the 91-92 style front pipe and 93-94 style rear pipe (no resonator) on mine. Dynomax does make a custom style muffler for the 93-94 Explorer (#17697) with a 2-inch inlet and 2.25 inch outlet, that seems to have less drone than the 17747. The difference between the 91-92 and 93-94 mufflers/pipes is the muffler bracket, on the 91-92 there is a 2-hanger bracket welded on the rear pipe, on the 93-94 there is just a single hanger, which Walker/Dynomax welds on the muffler itself at an angle. The 91-92 style is better for gound clearance and going off-road, since the muffler sits horizontal.

You might also try asking at Advance if they carry a rear pipe from their other exhaust brand, ROL. Their rear pipe for the 91-92 might have a resonator already installed. Midas might make one as well. Just keep in mind both these pipes might be thin and/or crush bent, so not really something that will last.

 

[malohnes]

I'm running the Gibson System, 2 years now and like it a lot. No issues, easy install and sounds great, not boomy and nor loud. I am running with a Magnaflow hi-flow cat along with JBA headers for my complete exhaust system. Anime has some great suggestions, but you asked about Gibson.

 

[vq5speed]

I've also have a Gibson catback stainless setup for over 15 years. Still looks good and sounds good.

 

[Bwana Bob]

Thanks, guys, for your inputs, especially Anime for the very detailed response.
Yes, I probably gave up on the Borla prematurely but at the time I looked on their web site and didn't see 1st generation Explorers listed, so I thought I was out of luck. By then, I had lost or misplaced my receipt, too.

Advance Auto doesn't list the Quiet Flow (22592) anymore, just the $30 muffler, but they do have the Dynomax 17747, which is listed as "mild sound", so it should be OK with the resonator. Might give a little better performance, too.

Rock Auto has lower prices, but Advance is offering 15% off plus a $25 coupon (which I'll put toward new brake pads for the Focus). Plus, I have the parts shipped to the store, so that if anything is not right, I can return it on the spot, instead of dealing with the annoyance of return shipping.

My Explorer is semi-retired. Maybe if I drove it more, I'd clear the condensation out of the exhaust. It seems to rust out and break right at the exit from the muffler. Would it be a bad idea to drill a small hole in the bottom of the pipe to let condensed water drain out or would that cause it to fail inspection? How about painting the parts with high-temperature manifold paint to help preserve them? The towns and state use a lot of road salt here in NJ, so maybe PM is the best approach is to get under, hose off the exhaust and underside, then drive it around to dry things off. This will only work after the roads are clear and we have a thaw.

Thanks again.

Bob

 

[Anime]

You can drill a tiny hole in the back (not bottom) of the muffler, at the lowest point, which can help drain some of the water and condensation that builds up. It shouldn't fail inspection if the hole is tiny enough, since many of Walker's own mufflers come with this drain hole feature. The best way to prevent (or delay) rusting from the inside out is to not take short trips - only drive the vehicle until it reaches operating temperature, which allows the exhaust to get hot enough to evaporate much of the water produced by the catalytic converter.

Painting the pipes with something like Rustoleum High Temperature manifold paint will prevent rust from the outside (and provide a tiny amount of heat insulation), but you'd need to be sure to clean the pipes well, and use the Rustoleum High Temperature primer so it lasts. I'm not so sure that painting the muffler is a good idea, though it might prevent rusting around the muffler seams, but the majority of rusting is really from the inside out, due to water from the catalytic conversion process. Lots of people just use the 2000 degree BBQ grill paint, but the Rustoleum manifold paint also comes in silver so it would look just like the aluminized finish. The only downside to the Rustoleum stuff is it needs to be cured, so you have to go through a procedure of running the vehicle at idle for a few minutes, then turning it off and letting the exhaust cool, then doing it again and again, so the paint heats up some but not too much each time.

As you mention, the muffler-to-pipe connections also get a lot of rust build-up, mainly because this is another route the water goes to escape, since the slip-fit connections aren't completely water- or air-tight. It happens a lot at the rear muffler-to-pipe connection because of how the pipes fit together - the rear pipe goes inside the muffler - so the flow of exhaust forces water into the space between the pipes. While it isn't a perfect solution, I've found that using band clamps (Walker makes them under their semi truck Mega-Clamp brand, part no. 33231 is their 2.25" stainless steel band clamp, part no. 33975 is their 2.25" aluminized steel band clamp) makes for a solid muffler-to-pipe connection at both the inlet and the outlet. Using these clamps also has the not-minor benefit of not crushing the pipes or muffler, keeping the exhaust diameter constant, compared to standard u-bolt clamps that crush the pipes and muffler. The big benefit is also that the pipes will come off the muffler easier when you want to disassemble or remove it. Some people use anti-sieze on the pipes where they contact the muffler inlet-outlet, although this can get messy since the stuff gets everywhere. This also prevents rust, makes a slightly tighter seal, and makes disassembly easier. The real "fix" to this would be a slip-fit in the other direction (muffler outlet goes into exhaust pipe), but this would require some minor custom work, with expanding the rear pipe to fit over the muffler outlet, and the use of exhaust flanges and gaskets to make the connection.

If you can't find a replacement for the Walker Quiet-Flow locally (although Advance might be able to order it in-store even if it isn't listed online), you can call Walker directly and they will help direct you to the closest retailer that will warranty the muffler, or they will do it directly. Even if you decide you want the Dynomax 17747, you can call Walker and ask to trade up under their "safe and sound" program. If they agree (which they should because you're just swapping one Walker product for another for the exact same application) They will require you buy the 17747, provide proof of purchase, and they will provide a shipping label to return the used Quiet-Flow muffler directly to them. If nothing else, I would still suggest getting a new Quiet-Flow muffler under warranty rather than throwing the old one out so you can either sell it or just keep it as a spare or if the Dynomax drones and you decide to just swap it back for the Quiet-Flow.

There have been some $50 off $100+ coupons for Advance recently, so if you wait and look out for one of those offers, you might be able to score an even better deal on the muffler and brake pads if that's a bigger discount than the 15% and $25 off.

 

[Bwana Bob]

Thanks, all for you inputs.

I finished the job a few weeks ago. I bought the OEM-style Walker pipes and the Walker Dyn-o-max muffler, which I found to be very quiet. I don't know if it improves fuel mileage or performance, but a first generation Explorer with 243000 miles on it is hardly a performance vehicle anyway.

As always, getting the old front pipe off was the biggest challenge. I had to use my Roto-zip with a diamond wheel to cut one of the spring bolts.

This time I used stainless steel nuts and lockwashers on the spring bolts instead of those awful nuts with the tabs on them.

Thanks, Anime, I found stainless steel band clamps at an area Autozone. They are far superior to U-bolts. At first I installed them incorrectly, but on inspection found them to be loose, and I quickly corrected my error. [The clamps do not install the way they are assembled in the package]

I also gooped everything with anti-seize grease.

There is still more minor stuff to do, but at least the old Ex is road-worthy again.

Bob