My exhaust is falling apart

[tjsxplodr]

Ok then, so would the tranny swap into the V8 be easier and less costly?

I am VERY partial to my 5 speed and 4 doors. I don't mind the looks of the sports, but I love my 4 doors. It HAS to have 4x4 too.

I'm just worried about dumping a bunch of money into my sagging V6, when I know now, it had been rearended in the past, and I didn't even know that when I bought it. Whoever got rearended, fixed it, but the rear fenders are now starting to rust where the bent fenders were undone. AND, if I lift the carpet in the back, I can see where the metal was crumpled in the impact. Will this make much difference in restoration?

AND,

another issue I'm coming up with is that I'm being told on several sites that there really aren't any mod parts available for the aging 1st gens. I'd love to beef up the 4.0

 

[Anime]

I haven't done either a manual tranny swap into a V8 or a V8 swap into a first gen, so I don't know firsthand which is more expensive or time consuming. Popping a bolt-on 5 speed behind an existing engine would be the easier of the two on a 2WD, but if you had to have 4WD...that might make it difficult.

Nothing's wrong with dumping money into the V6. A 91-92 V6 needs it, too. The heads are a weak point and usually crack, so new aftermarket heads ($400 a set) are needed, and the factory rockers on almost all OHVs wear down and need to be replaced ($160/set), and while doing that you go ahead and have all the top end gaskets (~$100)replaced too.

The bent rear end and rust isn't much of a problem, you can do bodywork or just grind the rust off and paint. You can try and pound the metal back to how it was, but it will still be pounded metal. There isn't much of a cosmetic or structural fix other than cutting out the old stuff and welding in new.


It's true that despite it's popularity the first gen Explorer didn't get a whole lot of aftermarket junk, but there's enough stuff out there. You can beef up the 4.0L with lots of available performance parts and spend as deep as your wallet is, but the issue is more that the cost usually outweighs the benefit after you go beyond basic (intake, exhaust, heads, etc.) engine mods.

 

[tjsxplodr]

Yeah, see that's what I was afraid of. More cost vs the benefit of doing aftermarket modding on the 4.0. I'm not trying to say I want a sports car in an SUV, cuz I already have that in my '03 Mach 1. If I keep the rig, I just want to have more get up and go than the 4.0 has. Anyways, its going to be a tough decision.

 

[Anime]

...You have a '03 Mach 1?

I was assuming the Explorer was your primary vehicle and possibly your only vehicle.

If you have a sweet ride already, that's a bit different. First gens make a GREAT play toy if you want a 4x4, and they are the preferred platform for an Explorer-based trail rig.
If you ever plan on lifting it, doing a solid axle, etc, you would be pressed to do better.

The 4.0L OHV has plenty of get up and go, it's just that certain known factory defects (heads, rockers, sometimes pushrods/lifters, clutch/master/slave cylinder, etc.) need to be taken care of to get it back to top form. It's also a low-end torque engine, so it's limited RPM range without modifying the top end with a cam and associated head hardware to go along with it is a different kind of driving compared to a high-revving sports car.

If you just wanted a trail rig you can fix up and drive without worrying about babying it, the Explorer you have might be just the ticket. Drop a grand or so into it for basic maintenace to get it up to snuff and it should be good to go. After that, mod to your heart's content.

If you want something less like a fixer-upper and more like an everyday 4x4 SUV you can just hop in and not worry about fixing anything, you might have to spring for a newer ride in better shape.

 

[tjsxplodr]

Yep I do have an 03 mach! She's my baby have had her since 08. She's NOT a daily driver. More like a garage queen especially during the winter. She hasn't seen snow nor will she. I want my suv to be a comfortable daily driver more than an offroad rig. I've put more than twice what I paid for it back into it already lol. I dunno what to do with it lol. There have to be ways to make these older rigs more friendly to daily use lol.

 

[Anime]

The first gens are fine for daily use especially in stock or semi-stock form, you just have to put in the time/money to fix known issues. You can get by with just fixing things as they come up, and the OHV will run until it just isn't getting any fuel or something prevents it from doing so, but as a go anywhere ride it's far more reliable, not to mention more of a pleasure to drive, if you just spend the money and fix the stuff.

If the engine that's in it has big problems, and the engine you bought is in good shape, you might consider building it up then swapping it in if that's all it needs.

As for the exhaust my suggestion stands for the Dynomax. If you want a little more get up and go, a KKM intake and a Super Turbo catback is the way to go. Flowmaster makes a catback kit if you like those better, though.

If you don't want the slight increase in noise/drone from a catback on a DD, get the Walker muffler instead, and just use the Dynomax rear pipe. It flows almost as well, it just doesn't have the design of the Super Turbo.


If your XLT isn't as comfortable as you'd like for daily use, maybe you could upgrade to an Eddie Bauer or something. Plus there's always the newer 3rd-4th gens. Maybe get an '03 to match your Mustang.

 

[tjsxplodr]

Are there any seats from any other years that would fit fine in the 1st gen? I thought about sticking a full bench seat from a pickup into mine, but not sure if that will fit.
I have an aftermarket catback on my mach 1 that makes drone at 2k, its not horrible, just tolerable. As long as those catbacks aren't horrendously loud, I think I'd rather do that than piece it together. Would it be advisable to replace the cat converters too, the exhaust complete from the headers on down?

I thought about building up the motor that I have. I have an engine stand, but no place in our garage to do the work. Supposedly that motor that I bought's only got 86k miles on it. It needs work though, some parts need replaced: harmonic balancer, fan, belt tensioner. That's it as far as I know. I haven't pulled the thing apart at all. I know when I took my Ex to the dealer to have the spark plug hole looked at when the plug spat out, they told me that my rockers and **** there was something else I can't remember the name to that were going bad in my engine. WELL, DUH! The motor's got over 200K miles on it idiots! LOL!

That deal just seems like a LOT of work to pull the spare motor completely apart. I'd need a hell of a lot of room too, which we don't have.

I know I could make it more comfortable with different suspension setups. And putting in some better seats might work too.
I need to redo my headliner too, that's gonna be a *****.

 

[Anime]

Most seats up through '01-02 should fit directly into a first gen. First gens were available with a bench seat, but I don't think it's as comfortable as the captain's chairs or leather buckets. A bench seat also might interfere with a floor shifter.

I have the 91-92 Dynomax on my '93 (it's larger tubing and flows better than the 93-94 muffler) and it does drone at 1800-2000 RPM, not unlike a Mustang. It's not too noticeable with the windows up and a full interior, but it's noticeable with the windows down, and if the interior is stripped, it becomes very annoying. I like the gurgle and tone of it though, the deep exhaust note fits the OHV perfectly, and compliments the addtional noise from the intake. If you like a deep performance sound, get the Dynomax. If you want a stock sound and don't want to hear the exhaust from the interior, get the Walker. If you do get the Dynomax, you'll probably want the KKM intake. Just a drop in K&N filter would go fine with the Walker.

I wouldn't replace the converters unless they are clogged. The factory converters flow just fine. Headers are very expensive, since the only good ones are stainless JBAs at about $600. There are mild steel headers out there (Pacesetter, Heddman) but they have fitment and quality issues. Headers are also generally regarded as a low bang for the buck mod since the factory manifolds flow just fine at the normal RPMs the stock motor sees. If the motor gets a lot of internal work, and more airflow is possible, headers make more sense.

You could take the stuff the other engine needs off the engine that is currently in the Explorer when you do the swap. The rockers in the OHVs just wear down since Ford didn't design enough oil flow into them, and the metal is apparently softer than needed to resist the wear. Ford sells revised rocker kits that deal with the problem.

It is a lot of work, but it's worth it if you want to keep that particular vehicle.

Shocks and rubber bushings seem to make the biggest differences from what I've seen. Performance shocks make it ride firm, regular shocks give a nice stock ride. A lot of people replace the factory rubber bushings with polyurethane bushings, which firms up the suspension, but transmits more vibration. Rubber bushings for everything (except the sway bars, maybe) will give a cushy ride.


You'll have to decide what sounds better, putting in the time and money to make this ride how you want it, or cutting out and selling it off to get something newer you won't have to do much work on.

Right now, to me, it sounds like you'd be happier selling what you have, then using that money towards a newer Explorer with a high trim level. That way you don't have to deal with running issues (at least until much later) and can add and modify as you want.

 

[tjsxplodr]

I got under the x today. Couldn't really tell what's rattling. The heat shields r all in place, the hangers r intact as far as I could tell. Felt around, the hangers r intact, but loose. Could b the source. I'm just goinkg to drive it as is. I would love a 98 or above ex with the 5.0...would have to do a tranny swap tho for sure. For right now tho, I've decided to keep it running.

 

[tjsxplodr]

What kind of parts would be good to upgrade the engine? I'm not familiar with brands/parts for the 4.0 engines. What parts specifically should be upgraded besides the heads? What parts can I leave in the engine that I have stored?

 

[Anime]

Aside from the heads, the issues I mentioned are with the rockers, due to increased wear, which causes the tick/rattle at high mileage. It's usually a good idea to replace the pushrods at the same time, since they make contact with the rockers and can also be worn.

My suggestion is for genuine Ford parts, and ONLY genuine Ford parts for these items.

They are easily sourced from Tousley Ford, (forum member FORDSVTPARTS) about $90 for each rocker shaft assembly (cheaper than buying each rocker, and you get all new EVERYTHING, even bolts, and makes it a snap to pop the old ones out and new ones in) and about $5 per pushrod (you'll need 12 for a V6)

There are some refurbished/rebuilt/remanufacturered and aftermarket parts for these, but there is no reason to buy them when you can get the revised stuff from Ford for less money. I bought these parts from Tousley for my Explorer and can vouch for their superb service.

You will likely also want to replace all the gaskets (valve cover, lower intake, upper intake, etc.) when doing this, and the Ford gaskets are regarded as the best choice...or the choice if you want to do it once. They are also the best choice for head gaskets as well. Fel-pro is an okay fallback choice, and their upper intake is fine, but the Ford lower intake seems to be much higher quality and leak-free than aftermarket stuff.


As for the engine heads themselves, there are a few places nationwide that have good ones. When it comes time for heads on mine, I will likely be going with Alabama Cylinder Head. Location has a lot to do it with as well, so you may end up going with some other place, either due to the lower shipping cost or a better price at the time. Mostly it's important to get a NEW head, and of the variety that is thicker (and therefore, heavier) than the stock 91-92 90TM heads. You MIGHT get away with using later 93-94 heads, BUT they are still not as thick as the right aftermarket stuff.


The other upgrades are the basic intake and exhaust.

I highly recommend the KKM (Kurtz Kustomz Motorsports) intake. It's a bolt-on and comes with the MAF adapter and a high quality S&B filter. You can buy it directly from their website.

I also recommend the Dynomax catback exhaust. You can get this at Advance Auto Parts or NAPA, or online through performance retailers.

Note that Advance Auto Parts currently has online coupons for say, $40 off $100, or 20% off, plus free shipping for orders over $75. You could feasably buy the Dynomax system online, use the coupon, and have it shipped for free.
Dynomax also offers mail-in rebates from time to time, too. Last year they had a big rebate, and along with online sale pricing, many members wound up getting their systems for $20-50.

 

[tjsxplodr]

Oh sweet! Thanks for the information. The easier the parts are to find, and the easier the installation the better for me.
I'm pretty sure now that I'll be getting the Dynomax catback exhaust. I will need to find new headers though for sure, since mine are rusted..ewww.
Man, for the price I'm going to be paying to do all this to my ex, I could have one that has no issues, but I really love my '91. It's sturdy, and I've only had to fix what has been neglected over the years from whoever had it before me. The guy I bought it from got it at auction, so he had no clue what the history was.
WELL, I know now that it had been rearended...as I was saying earlier. But it hasn't changed the way it drives. At least not that I can tell.
The engine in it now I'm fairly certain has passed 220K miles. I've put full synthetic oil in it. Seems to keep it running better than with the other oil.

I can't wait to take care of that exhaust problem! The rattle is bad. When I hit about 1900 rpm, it sounds horrible lol. But, I couldn't find anything really that could be the source. Prolly just a bad exhaust ready to go.

ANyways, thanks for all the information. Have you done an engine rebuild and what advice can you give me on this one?

 

[Tony H]

You mentioned it rattles at certain RPM's so it isn't just loud. I would check the Cat. It has a metal protective cover over it designed to keep tall grass from catching fire. The small spot welds break making it resonate at certain RPM's.
After not being able to weld it in teh rattle spots, I joined a few hose clamps together and put it around it. that stopped the rattle.

 

[tjsxplodr]

Ahh ok thanks. I didn't check the cat at all.

 

[Anime]

Rust on the stock manifolds isn't a problem. If you plan to get headers, the time to do it is while replacing the heads, though. You can always have the manifolds ceramic coated instead though, which will reduce underhood temps and flow exhaust gases better, for much less than the cost of good headers. Keep in mind the only good ones out there are the JBAs, and theirs, ceramic coated, are $600. You can get cheaper ones, but they suck, and will radiate heat like crazy. They will make noise though.

I haven't done a rebuild on the motor, since going by others who have, there is no need. The stock motor at 200-300K usually has very little wear other than the parts I mentioned. Of course every motor will have it's own issues, and other things like the water pump, fan clutch, A/C system, etc. etc. will eventually fail/wear out and need replacement and repair, but that's part of owning an older vehicle and keeping it running. I may eventually rebuild at 400-500K or if/when there is ever a serious issue. My guess is I won't be doing much besides a head replacement if these ever crack, and a rebuild will just be a down the road thing once I have all the parts and the time and place to take my sweet time doing it.

The catalytic converter heat shield was mentioned early on in the thread as one of the top sources of exhaust system rattles on these.

 

[tjsxplodr]

Yeah, I have no idea what I'm going to do. I'm trying to figure out the cost vs benefit of keeping a 20 year old truck running vs buying a newer model.

 

[tjsxplodr]

So where are the best places online to buy oem and aftermarket parts for the '91 Explorers? There has to be a few sites that have lots of stuff for them.

 

[tjsxplodr]

Rust on the stock manifolds isn't a problem. If you plan to get headers, the time to do it is while replacing the heads, though. You can always have the manifolds ceramic coated instead though, which will reduce underhood temps and flow exhaust gases better, for much less than the cost of good headers. Keep in mind the only good ones out there are the JBAs, and theirs, ceramic coated, are $600. You can get cheaper ones, but they suck, and will radiate heat like crazy. They will make noise though.

So buying a new pair of stock headers and then having them ceramic coating would be best?



I haven't done a rebuild on the motor, since going by others who have, there is no need. The stock motor at 200-300K usually has very little wear other than the parts I mentioned. Of course every motor will have it's own issues, and other things like the water pump, fan clutch, A/C system, etc. etc. will eventually fail/wear out and need replacement and repair, but that's part of owning an older vehicle and keeping it running. I may eventually rebuild at 400-500K or if/when there is ever a serious issue. My guess is I won't be doing much besides a head replacement if these ever crack, and a rebuild will just be a down the road thing once I have all the parts and the time and place to take my sweet time doing it.


Yeah, the A/C has a leak in mine. It's been converted to the newer A/C stuff already, I just have to find the leak and get it fixed. The spark plug seems to be holding its place now that it's tightened and has anti-seize on it. I'm not worried about the heads...everything seems to be holding up just fine. Haven't replaced the water pump, yet LOL. I have a squeaking noise in the left front side, think its the coil spring isolator. I've had the radius arm bushings replaced.




The catalytic converter heat shield was mentioned early on in the thread as one of the top sources of exhaust system rattles on these.

Ok, that will be the first thing I check once it cools down this afternoon Thanks man.

 

[tjsxplodr]

I looked up underneath the ex today. I didn't see anything that's loose. Could the cats be bad inside? I pushed up on them pretty hard, and it sounded like the rattle was coming from there.



Is this the dynomax catback that you were talking about anime?
http://www.napaonline.com/Search/Detail.aspx?A=EXH17438_0221446362&An=599001+101991+50028+2028014

 

[Anime]

The performance stuff for first gens is spread out, there really isn't a site with all the best parts for them for one-stop shopping. Places like Summit and Jeg's have quite a few items, though. ExplorerExpress caters to us with a few items, but most have been removed or not restocked in favor of items for newer Explorers.

Keep in mind the 4.0L OHV doesn't need a lot, and just adding the intake/exhaust, along with cleaning the MAF, and a good set of wires with Motorcraft plugs, is about all you need to bother doing aside from regular maintenance. In this way first gens are a better budget minded machine that you don't need to bother with constantly throwing aftermarket upgrades on it to get somewhere. The biggest performance gains other than intake/exhaust are to be had by simply replacing the known defective stock parts like the rockers with the newer revised parts.

The stock manifolds, new, are fairly expensive themselves. ~$150 each from a dealer.
For the minor improvement it would give, and the extreme hassle of removing the manifolds from the heads with the heads still on the motor (and the associated risk of snapping off a bolt in the process) you are WAY better off leaving the stock rusty manifolds on there (especially if they don't leak), and then worrying about headers or having the manifolds ceramic coated if/when the heads are ever replaced or major engine work is done.

It's common for the A/C systems to leak on these. Usually it's the O-rings throughout the system. A lot of conversions are done without replacing ALL of the old rubber O-rings with newer green HBNR O-rings, which are necessary for R134a. There's a good chance you can just have the system evacuated, taken apart to have all the O-rings replaced, throwing in a new orifice tube (preferably of the variable orifice kind for maximum efficiency) and have it recharged with R134a, with no more leaks.

It's possible that something rusted off internally and there is a piece of rust inside the Y-pipe or between the cat and muffler that is rattling around. Catalytic converters are stainless steel so they don't usually rust internally, but it is still possible for their intenal parts to come apart, so that is a possibility, though unlikely.

Perhaps you can get a better idea of the souce of the rattle if you can create the circumstances when it happens, then do so with someone else behind the wheel, in park, parking brake on, and crawl underneath to listen for the source.

The Dynomax Super Turbo kit for the 91-92 4-door is part #17430:

It does come with U-clamps, but if you go with it, I suggest dropping the extra ~$20 for some Walker Mega Clamps (part #33231, 2.25" lap joint clamp) from RockAuto. They are stainless steel band clamps. They seal better than the U-clamps, don't rust, and make sliding the exhaust apart if you ever need to remove it or replace a pipe a breeze. They also don't crush the tubes, which helps keep the exhaust flow you paid for.