Top Mustang Problems
Whether you're looking to buy or trying to keep your Mustang on the road, these top problems are something to watch for
From the January, 2013 issue of Mustang Monthly
By Mark Houlahan
Photography by Mark Houlahan
We love our Mustangs; that's a fact. Some only love the early cars, while for some a Fox body will always have a place in their heart. It doesn't matter if you prefer modified cars or museum quality concours trailered examples, all Mustangs have issues. We sometimes try to ignore the elephant in the room, but we are quickly snapped back into reality when one of the Mustang's common problems smacks us in the back of the cranium.
Any car can have problems, that's a given. However, when you're talking a 45 year old Mustang, it's in a whole other realm of possible issues. It might be common to deal with a squeak and rattle or two on a five year old daily driver, but what if the Mustang in your garage is a 25 year old Fox Mustang? Perhaps you're just getting into the hobby and are looking to fulfill that high school dream of owning a '65 Mustang fastback? Now we're talking a 47 year old filly. Have you ever seen four decade old wiring? Maybe some of you home restorers know what we we're talking about, but generally, the older the car, the more problems you'll be dealing with.
Age isn't the only factor when it comes to Mustangs. How they've been used and where they've been used both play important roles in if these common Mustang problems rear their ugly head and how bad the problem is. Certainly there is an increased chance of rust problems on a Mustang driven every day of its life in Minnesota versus a Mustang driven daily in Arizona or southern California. The same can be said for a Mustang that was used as a daily driver and never modified versus one that racked up its mileage a quarter mile at a time has been modified with a bunch of speed parts.
We polled several people, from industry insiders to long time shop owners and even local club members and asked them what they've found to be the Mustang's biggest problems over the years. Some will be obvious; others not so much. We don't have the room here to go into detail on how to fix all of these issues, but where we can we'll lead you in the right direction for parts or how to solve the problem (or even prevent it if it hasn't happened to your Mustang yet). Lastly, we know there are a whole lot more than 10 problems you can find in a Mustang. You could probably find most of these all on one car for that matter, but we took the answers from those polled to create this top 10 list. Feel free to share your Mustang problems with other readers on our magazine forum at http://forums.mustangmonthly.com/ and if you have a fix for the problem be sure to post that as well!
10: Parts is Parts
As soon as you head down the path of modifying your Mustang, no matter the year or body style you will quickly run into fitment issues with aftermarket parts. We're not always referring to the part fitting on your car here (though that can be an issue); no, we're referring to the fact that most aftermarket companies design their parts around a stock vehicle and short of their own product line, can't account for every aftermarket part ever made to work with their parts. Once you've installed that performance brake kit don't be surprised if the new suspension you install a few months later has interference problems with the brakes. Then once you get the suspension figured out the next shocker is trying to fit the performance exhaust designed around the original suspension and not your new whiz-bang four-link. Buying parts from the same vendor does not guarantee that they will fit. Vendor's catalogs are filled with parts from many sources and they do not have the manpower to test fit every part they sell on every model/combination. It is up to you, the consumer, to do your research and make sure the parts you want fit with what you already have or plan to install, or be willing to start modifying things (and not jump on the Internet and gripe things don't fit). If you want a supercharger on your vintage Mustang you're most likely going to have to live without air conditioning unless you go to a custom bracket from an alternative source or modify the kit to your needs.
A simple disc brake upgrade...
A simple disc brake upgrade is a common purchase for vintage Mustangs, but go big and you need larger wheels. Larger wheels might hit the upper ball joint. See how the snowball starts to get bigger?
As mentioned below, a supercharger...
As mentioned below, a supercharger install usually sits where the A/C compressor lived, so unless you’re willing to give up your A/C (or the ability to upgrade to A/C in the future) you might have to find a different way to mount the supercharger you’ve been dreaming of.
9: Improper Repairs
Why someone would weld a bumper...
Why someone would weld a bumper support onto the frame rail is beyond us. Especially when you can see the mounting hole in the frame rail is in good shape too! Maybe they were in a hurry and didn’t have a couple of 5⁄16-inch bolts lying around—who knows. All we know is that to fix this is going to require some manual labor and possibly new bumper supports.
Everyone thinks they're capable of making a solid repair and pocketing the savings. The truth is most enthusiasts are shade tree types at best. The important factor to know here is your limitations. We've seen people buy welders and other shop equipment to fix the rust on their vintage Mustang only to blow holes in the sheetmetal or not have enough penetration on their welds for the repair to be solid/safe. The owner then gets frustrated and takes it to a shop where they charge a fair rate, yet the owner is upset because they just wasted $800 in sheetmetal parts and have a $500 welder taking up space in their garage they'll never use again.
Whether it is inferior parts or inferior workmanship, or both, improper repairs often lead to further damage as time goes by. Fixing it right the first time, or paying someone that knows how to will honestly save money in the long run. This is probably one of the biggest issues we find when looking at potential cars to buy (or helping a club member to look at a car they're thinking of buying) next to rust in vintage Mustangs. A Mustang that looks decent at twenty feet could be hiding numerous bad repairs, causing the over-all purchase price to go up exorbitantly once these bad repairs are found and corrected by the new owner or by a competent shop.
A simple brake shoe replacement...
A simple brake shoe replacement becomes a nightmare because the previous owner cross threaded the retaining nut. Luckily the local parts store had a universal spindle nut kit on the shelf and we had one of the best tools ever made—thread files! Do yourself a favor and pick up a set of three—coarse, fine, and metric threads. You will thank us many times over!
Nothing like four feet of...
Nothing like four feet of rubber fuel line (AND a plastic fuel filter!) under the hood to scare the crap out of any potential buyer. How this car didn’t burn to the ground we’ll never know, but a section of steel fuel line and just a few inches of rubber hose is the correct way to route a custom fuel line for the Edelbrock carb installed on this ’66.
8: Non-Original Parts
Upgrading a Fox Mustang to...
Upgrading a Fox Mustang to five-lug brakes opens up a huge selection of cool wheels to install. A great budget way to do this is with Lincoln front rotors and Ranger rear axles and brake drums. However, what happens when YOU buy this modified Fox and later need to buy a replacement brake rotor at your local parts store? The counter jockey, after asking you the usual “is it a 5.0? Does it have A/C?” and then slides a stock four-lug rotor across the counter at you. “Um, that’s not right,” you state, to which your frustrated counter man says “that’s what the computer says it uses.” See what we mean about knowing your Mustangs?
When we're speaking of non-original parts, we're not referring to aftermarket parts, as we just discussed that in problem number nine. No, this little gem of an issue is referring to original Ford parts, just not on the right car or the right year. Let's face it, after four decades on the road a lot of vintage Mustangs have been repaired or upgraded with parts from other years and model Mustangs (or even Fords). A first time vintage Mustang buyer may not realize those disc brakes came off of a Granada, so when they order new tie-rod ends and then they don't fit the first thing that happens is an angry call to the vendor stating they sent the wrong part—but did they? Another perfect example is buying an upholstery kit for your '67 Mustang, yet it has newer seats in it that came with it when you bought it. The key here is to know your car and know what you have. Research it, look at other cars of the same year and model, ask the seller questions, and for vintage Mustangs pick up a copy of the Mustang Recognition Guide. These will all help you to become more educated on Mustangs in general and will help prevent parts issues, delays, and angry calls to your Mustang vendor when all they did was fill the order with the parts you asked for. 7-Availability of Parts
We've often said that you can build a whole '65-'68 Mustang from a Mustang parts catalog, and that has never been more true with the inclusion of reproduction body shells that are now on the market. However, as you move into the '71-'73 Mustang market, or the '74-'78 Mustang II market the availability of replacement parts drops considerably. We're not talking only restoration parts to restore these cars, but even basic service parts from your corner auto parts store are often hard to come by. We'd be remiss in mentioning the early Fox as well. The '79-'86 Mustangs had different interiors and drivetrain parts than the more utilized '87-'93 models. While companies such as National Parts Depot are working hard on early Fox restoration parts, some of these items may never be reproduced due to tooling costs and low sales volume. Parts like urethane bumpers for Mustang IIs, 13- and 14-inch tires for stock Mustang wheels, and more. Even some later Fox parts are obsolete from Ford and not reproduced (anyone have a working door chime module they want to throw my way for my '90?).
6: Unbalanced Cars
Oh to be a Mustang II enthusiast....
Oh to be a Mustang II enthusiast. These poor guys really have it tough when it comes to the availability of reproduction parts. Somehow they persevere to keep excellent examples like this King Cobra on the road and show field for us to enjoy.
It's pretty much an un-written rule that car people like to drive fast. Let's face it; everyone has a little Ricky Bobby in them. But some people take it to the extreme and end up creating a very unbalanced car. We often see this more with late-model Mustangs, but restomod vintage Mustangs can be just as bad a problem. It starts off with a nice stroker small-block, then maybe a blower or turbo. Next thing you know you have 500-plus horsepower at the tire and you're running on stock brakes. This is especially bad on a vintage car (we've all seen a nice high-powered crate engine under hood with manual front drums peeking through the wheel spokes), but this is usually more of a Fox-era problem, as these cars had woefully inadequate brakes. Just ask SCCA Escort Endurance champion Rick Titus, who told us one time that they used to use the Camaro's rear bumper in racing to help slow their Mustangs down! So plan your build or upgrades as a package. Power, handling, brakes, and of course comfort and safety, should all be planned out and built together.
The Fox-era Mustangs are seeing...
The Fox-era Mustangs are seeing a boom in reproduction parts. Just a few short years ago these trashed Sport seats in this ’90 convertible would have been junkyard fodder. Now, thanks to companies like TMI you can order stock replacement foam and upholstery, or even modify it with custom colors and materials.
If you didn’t think it was...
If you didn’t think it was possible we have the picture to prove it. This unassuming, yet clean, ’68 coupe puts down a dyno-verified 632 horsepower to the tire via a stroked 351 Windsor. A hint of what kind of power this car wields is evidenced by the discreet roll cage and drag radials out back. The owner kept the package principal in focus while building too, as the car runs power disc brakes, performance radial tires, upgraded suspension, high back seats with belts, and more for a balanced street/strip ride.
’71-’73 Mustangs are slowly...
’71-’73 Mustangs are slowly starting to see more reproduction parts availability. Why? We firmly believe it’s because there’s hardly anything left to reproduce for the ’65-’68 models!
5: Engine/Drivetrain Issues
While there’s no denying the...
While there’s no denying the allure of a crate-engine and its drop-in-and-go simplicity, often rebuilding the original engine is a better idea (date code, numbers matching, clutch bar pivot, etc.). Having an engine machined for home assembly, or having the shop assemble it, is your choice; with the later costing more naturally.
Your typical Mustang owner is usually pretty good at light mechanical work (replacing valve cover gaskets, swapping a radiator, etc.), but when you get into the heavy stuff—engine rebuilds, differential upgrades, etc.—then problems often arise. Your typical small-block engine has dozens of moving parts that have several things to watch out for when rebuilding. Clearance specs, torque specs, and so forth, that you must rely on a machine shop for machining and or installation. Finding a reputable shop is your first task, albeit not always an easy one. You should check with local enthusiasts, club members, and so forth for recommendations. The last thing you need is a poorly machined engine that makes noise, leaks, or doesn't even run after shelling out hundreds of dollars in labor and more in parts.
If your drivetrain is in good condition you're already a step ahead. Keep it that way with regular maintenance that you can do at home. Oil changes, fluid flushes for the trans and rear, and the like. When you start your Mustang let the oil get up to temperature before any spirited driving. Always ensure your drivetrain's fluids are topped off and that you're using the right viscosity (no 90W gear oil in a modern transmission for example). Doing these preventive measures/checks will keep your drivetrain running strong and you out of the machine shop for many years of ownership.
Typical of the people we spoke...
Typical of the people we spoke with, machining and assembly of the “short block” was handled by a competent machine shop and the rest of the engine was assembled at home. One of the biggest problems we see for first time engine “finishers” is installing the head gaskets backwards, causing immediate overheating. Ensure the gasket is positioned with the word “FRONT” towards the front of the engine. On an engine already built you should see a tab from the head gasket sticking out between the block and heads at the front of the engine. If not, you know the first thing you’ll be doing to your new purchase is pulling the heads.
Saving your pennies for your...
Saving your pennies for your Boss 302, Shelby, or other dream ride may turn into a nightmare if that rare engine has issues or even missing parts. Emissions components, rev limiters, special Shaker components, and more that might be inoperative or missing will cost big bucks to find and replace. Know what you’re looking at going in.
4: Door Hinge Failure
The aging Fox platform has...
The aging Fox platform has seen a huge surge in restoration parts available to keep these beloved late-model Mustangs on the road. Unfortunately, the chassis side of the door hinges are welded to the chassis, so take care of those hinges and don’t use the door as leverage for getting in and out of your Fox ride!
To be honest, door hinges have a rough job. They open and close, often a dozen times a day, plus carry the weight of the fully loaded door shell (glass, locks, regulator, etc.). Some fail from age and tens of thousands of opening and closing events, while others live much shorter lives because they are stressed by owners using the door shell to aid ingress/egress or from people leaning on the open door. This isn't a vintage only problem, though it is more prevalent in the early cars mainly due to the age of the hinges. Early hinge failures are usually from the door check or check spring, but can also be the pivot points as well. The majority of late-model hinge failures (of which are primarily Fox body, but we've seen some '94-'04 Mustang hinges going bad too) is of the pivot pin itself. This requires a replacement pin and bushing kit, which is widely available through many late-model Mustang vendors. However, Ford changed the hinge design in the SN95 cars, so not all hinge/bushing kits work on these cars. As for the vintage hinges, there are reproductions of the complete hinge as well as repair kits for the door check plate and spring.
3: Overheating/Cooling Issues
A high efficiency aluminum...
A high efficiency aluminum radiator and high-flow electric fan combination, like this excellent Flex-a-lite Flex-a-fit radiator kit for early Mustangs, is an excellent upgrade. Just remember, it’s not a catch-all cooling fix for other ailments that create overheating!
Nobody likes a coolant leak, but overheating is the worst. Overheating not only shortens the lifespan of your engine and ancillary hardware, but at best is embarrassing and at worst can leave you stranded in the middle of nowhere. Cooling system issues can happen to any Mustang, old or new, stock or modified. Generally speaking, many people don't understand how the typical automotive cooling system works and they think a pretty aluminum radiator is the savior of cooling issues. We're not knocking aluminum radiators—we prefer them actually—but they aren't going to fix a cooling system that overheats if the issue is the head gaskets are on wrong, too large of an overbore on an engine rebuild, too low or no thermostat, and so forth.
If you're looking at a Mustang to purchase and you see a new radiator, new water pump, new radiator cap, etc. it should be a warning sign that maybe, just maybe, the owner is throwing parts at a cooling problem. We've seen people spend hundreds of dollars on radiators, fans, cooling flushes, and more only to still have a “problem” and it turn out to be a bad gauge! Again, this comes back to knowing your Mustangs. Properly diagnosing the issue is key as well. Short of a concours car these days EVERY Mustang on the road should have an overflow system with a proper radiator cap that allows the system to expand and contract properly to prevent fluid loss. Of course major mechanical issues like the previously mentioned overbore and head gaskets will require digging deeper and possibly bigger dollars to fix.
2: Electrical/ Wiring
There are several ways to...
There are several ways to connect add-on circuits or repair damaged wiring. The hardware you see here is NOT how to do it. The white and blue plastic wiring tools are called insulation displacement connectors, or more commonly by the 3M brand of Scotchlok. They have no use outside of an emergency or temporary installation in a location that will not see rain/dirt/snow. The small brass terminal is called a fuse tap and is designed to slip over an existing blade fuse to allow an additional wire to be added on. These things usually damage the terminals in the fuse box when used. Learning to properly connect, crimp, solder, and shrink wrap wiring with quality terminals (not the 1,000 pieces for $4.99 garbage) is a must for any enthusiast.
The true weakness of most car enthusiasts we know; electrical repairs/upgrades often separate the men from the boys. We'd need another six pages to tell you about just the top 10 electrical issues we've seen over the years, many culled from human error or lack of knowledge/understanding. There's nothing that'll stop a car in its tracks quicker than an electrical issue (or even prevent it from making said tracks in the first place, as the case may be). Understanding basic electrical systems and how a circuit works will go a long way to ensuring you repair or upgrade your electrical system properly using the correct size wiring, circuit protection, and more.
When the owner of this Mustang...
When the owner of this Mustang told us he had an issue with the battery always dying on him and burning up ignition switches a quick inspection found this bundle of burned and shorted wires shoved up under the dash. Part of the harness was resting on the edge of the firewall opening and cut through the insulation, creating a short/draw on the system. It’s been patched for now, but this car needs a whole body harness solution.
Wiring in 40 year old Mustangs is downright scary. Once again, short of a concours type Mustang we encourage owners to upgrade to full replacement harnesses. These kits not only offer modern TXL wrapped wire with modern blade fuses, but they include additional circuits for modern upgrades like high-output headlights, electric cooling fans, power windows, and more. Even Fox Mustang wiring is getting into the twenty-plus year age and we see many broken connectors when trying to service Fox electrical components.
The number one rust issue,...
The number one rust issue, by a long shot, is floor pan perforation. The Mustang’s floors rust from several factors, including leaking cowl vents, tire splash, lack of exterior protection in harsh climates, leaking windshield gaskets, and even leaking convertible tops.
The Mustang’s cowl vents (shown...
The Mustang’s cowl vents (shown here after removing the top of the cowl for repairs) are themselves a rust issue. However, once they have began to rust and allow water into the interior the rust continues due to wet carpets and trapped water, rusting the firewall, toe boards, inner rockers, floor supports, and the floor itself.
A jewel like this early fastback...
A jewel like this early fastback might be considered by some a great project at a low entry price for getting into the hobby, but you’ll spend thousands of dollars in sheetmetal and labor just getting the car back to a solid foundation to build from. If you have the skills and tools to do so that’ll save you some money, but don’t expect any car of this condition to be a cheap build that you’ll have on the road in just a few months (try a few years!).
1: Structural/Sheetmetal Rust
This comes as no surprise to anyone that has ever worked on a vintage Mustang that rust issues are the number one Mustang problem. From damage due to daily driving in the “rust belt” to improper accident repair damage, rust is the arch nemesis of vintage Mustangs. But don't think it is a vintage only problem; not by a long shot. We've seen many a Fox Mustang and even some SN95 Mustangs with rust issues due to winter driving, salt air from the ocean, or bare metal left from repair work. Repairing this rust damage can be a long, drawn out process, as you will often find that as you cut away the rust damage you'll find more rust damage behind/underneath. If your quarter panel has some rot to it you'll rarely get away with just a quarter skin replacement. The typical repair includes the trunk drop-off panel and the outer wheel house (at a minimum).
Besides rust repair being such a large project it is also an expensive one, causing lightened wallets across the hobby. Sheetmetal is not cheap, and often you'll find small brackets/braces that are not reproduced and hard-to-repair areas that you simply have to create custom patches for. The job is a messy one that requires plenty of room for tear down, support of the structure for proper repairs, lots of cutting and grinding, and of course welding the new metal/patches in. It's a dirty job Mike Rowe would be proud of and also takes a fair amount of skill and knowledge to understand how the Mustang's unibody is connected to prevent causing more damage with a poor repair.
We've said this before in various buyer's guides but it pays to state it again—buy the cleanest, rust free Mustang you can. Short of a family heirloom you'll often spend more than the cost of the car just in metal repairs and prepping the body for paint. Frankly, rust repair is the one major project we see most where people give up and abandon their dream project. Know what you're getting into before you buy and for those lucky enough to already have a Mustang in their garage you need to be vigilant about keeping the car clean. Ensure the body and door drains are clear to allow water to escape. Keep the car out of the weather as much as possible with garage storage.
A Word of Thanks!
While we've been in the hobby long enough to see all of these problems ourselves, we spoke to several others to ensure that we were on the right track. By trading emails, phone calls, and horror stories, this article came together with the help of the following industry friends, and for that, we thank them!
John Clor, Ford Performance Group (and Mustang II fanatic!)
Donald Farr, Editor, Mustang Monthly
Scott Halseth, Ford Product Manager, NPD
Merv Rego, Classic Creations of Central Florida
Rick Schmidt, President, NPD
Jim Smart, Mustang journalist and historian
Dave Stribling, Dave Stribling Restorations
Steve Turner, Editor, 5.0 Mustang & Super Fords