How to Buy a Used RX-7
By Rob Robinette
A Word about 3rd Generation RX-7 Reliability
Many people ask me about purchasing a 93-95 (3rd Gen) RX-7 as an only, daily
driven car. These cars are not known for their reliability and they are
absolutely scary in any amount of snow. Many, many people have had to replace
their engines well before 100,000 miles. And an engine overhaul is expensive
($5000 or more with labor) because the engine must be completely removed from
the car. The turbo control system is complex and prone to problems. Repair and
upkeep can be expensive because the cars are rare and most Mazda dealers are not
familiar with them. I've heard hundreds of horror stories from people that had
minor problems that were diagnosed by their dealer as something much more
expensive such as "need new turbos" when only a vacuum hose was lose,
or "need a new pre-catalytic converter" when the problem had nothing
to do with the exhaust.
I can't really recommend a 3rd gen for someone that doesn't have the ability
or desire to learn how to maintain it themselves unless you are lucky enough
(and rich enough) to be near one of the rotary specialty shops (PFS, Pettit,
Mostly Mazda, Rotary performance, KD Rotary, etc.)
The Test Drive
There are three things you must do before you buy a used 3rd gen RX-7 (93-95).
First, take a thorough test drive. Hook up a boost gauge and
verify a standard 10 psi boost to 4500 rpm then a drop to around 8 psi, then 10
psi boost in second gear. It’s easy to temporarily hook up a boost gauge to
the intake manifold (it has a built in nipple with a rubber cap) and then tape
the gauge to the windshield.
There are engine control problems that
will only show up when the car is fully warmed up. Look for smooth engine
operation during light throttle and full throttle acceleration. Look for a
"stumble" at 3,000 RPM under light acceleration. If the car does
stumble you need to realize it may be impossible to fix this problem. There are
some current owners that cannot
eliminate that 3,000 RPM hesitation but many others have solved the problem by
improving the engine to frame and battery to frame grounds. If the car doesn't run acceptably well then
don't buy it unless the owner brings it up to your standards before you buy it. Don't assume that new spark plugs or
a tune-up will make the car run right.
After the test drive, restart the car after about 30 minutes of cool-down.
The car should start easily and the idle should quickly stabilize at around 800
RPM. If it doesn't the engine bay may be too hot and causing vapor lock in the
The second thing you need to do before purchasing the car is have the
engine compression checked. This is really the only way to determine if the
engine is healthy. Many RX-7 owners have had to replace their engines around
60,000 miles so spend the money and get it tested (see the Compression
Test How To).
Finally, if you do buy the car see the Reliability
Modifications to make the car a little more bulletproof.
Thinking about buying an RX-7 but have heard horror stories?
By Tom Jelly
The 3rd gen RX-7 is a great car, but it does have some problems.
These problems by themselves are not serious in nature, but if not addressed can lead to
catastrophic mechanical failures that may damage the reputation of the marquee as well as
put a sizeable dent in your wallet. You must remember that this is a high performance
vehicle and requires maintenance commensurate with its capabilities. I will address each
item in order of importance, with the most critical items last.
The RX-7 has always been a high performance sports car as each new
generation was introduced. With performance often exceeding competition that was priced
far in excess (or for that matter, a multiple) of its purchase price, there are some areas
where sacrifices were made to save money, while developments in the high performance
aspects of the vehicle were well represented. The least critical of these areas are
interior trim. The black console, door and dash panels were, on the 93 cars at least,
coated with material that would not hold up. Many of these early cars had these panels
replaced under warranty.
Some early cars also had exterior paint problems, where the color
coat did not adhere properly to the primer. By now most of those cars have been touched up
or completely repainted, so don't disqualify a repainted car as a candidate for purchase.
The passenger door handles are very fragile, often broken and cost
$250 to replace, but can be repaired relatively easily.
There were 3 recalls on these cars- brakes (vacuum hose
modification), new (high temp) fuel lines and cooling system (pressure cap and fan control
module). These should already have been performed by now.
The inadequate ground wires between the engine and body should be
supplemented with heavy duty cable. In some cars this will remedy the 3000 rpm hesitation
that occurs when not fully up to operating temperature.
There are some vehicles with 5th gear synchro problems. The use of
Redline oil should prevent the problem from developing in the first place. If not, Mostly
Mazda has a spring kit that will help alleviate the problem. The 5th gear synchro
be cracked if there is a grind every time 5th is selected.
Proper (read- not too tight) belt tension is essential for water
pump ($200-600) longevity. With stock cooling systems, there is a specific procedure for
bleeding air from the system that must be followed when refilling or flushing.
The Mazda dealer service department may be the greatest threat to
these 3rd gen cars. DO NOT go to a dealer for service unless you get a recommendation FROM
ANOTHER RX-7 owner first. Many dealers are not properly trained to service these cars and
do more damage than repairs, but there are enough dealers and independent shops that
specialize in this particular vehicle that service should not be a major problem.
These cars, when fitted with just a few bolt on modifications, are
capable of tremendous horsepower gains, but these modifications must not be lightly
undertaken- proper fuel enrichment to accommodate intake and exhaust flow improvements
MUST be provided. If you are purchasing a modified car, make sure fuel enrichment has been
taken into account.
Remember, for a combined total of under $600 in reliability upgrades
(if you do most of the work yourself), you can have a bulletproof rotary rocket capable of
embarrassing some very exotic machinery. There is no need to be afraid of the car. It just
requires proper preparation, that although is not required for you basic Honda, will put a
huge smile on your face when you put it through its paces. As you surf the web, take a
look at the enthusiasm you see in the (many) RX-7 web sites you'll see. Racers, engineers
and other technically oriented types are HIGHLY represented among the ranks of owners.
People love the car for a reason, and these people wouldn't be so dedicated to the model
if it wasn't so special.
People keep asking me how to purge their cooling system. To purge
cooing system: fill the passenger side overflow tank to the full line on the dipstick.
Fill the black expansion tank near the IC to the top. fill the water pump mounted filler
to the top. Start the engine and turn on the heat till it blows warm. Shut off the car and
let it cool. *Remove the water pump filler cap. if the level dropped more than 1 inch,
remove the cap on the black expansion tank and fill it to the top. (if less than 1 inch,
fill water pump filler cap to the top, restart the car w/ heat still on, now you should be
OK, just recheck every day or 2 until the level stabilizes). Replace the cap and top off
the water pump filler cap. Restart the car w/ heat still on. Let it cool again. If the
level drops at the water pump cap again repeat everything after * until it the level there
stays within 3/4 inch from the top. If you can't get it to stay topped off after 3
Replace coolant overflow system w/ this setup: coolant_tank.htm
This should be done anyway because that little black expansion tank
will split from the heat. This has caused slippery coolant to spray out under the tires
and loss of control of vehicles in more than one instance. If you don't do the mod on the
web page, replace the expansion tank anyway with the one from Pettit (approx. $135) to
enhance reliability. If you still loose coolant, CAREFULLY check the hose from the black
expansion tank to the coolant recovery tank near the air filter. Even a tiny pinhole or
bad seal on this hose will prevent coolant from being siphoned back into the engine on
shutdown, which will eventually lower the level of coolant in the engine. If everything
still checks out, have the cooling system pressure checked and the spark plugs and oil
checked for coolant- you may have a more serious problem.
When looking for a used Rx-7, it is especially necessary to be patient and
discriminating. Do not be surprised if you look at a dozen RX-7's before finding
a good example. When it comes to mileage, the lower the better. There are far
too many ways for careless owners to abuse and neglect the rx7. Oil changes
should have been conducted regularly at every 3,000 miles or less. The car must
never have overheated in any circumstance. Further, there are many examples of
used rx7s on the market that have been "ruthlessly thrashed" on the
race circuit or damaged by an unexpected off road excursion. There are three
recall notices that must be done to any perspective rx7 is not completed
already. The first is a coolant recall which replaces parts of the cooling
system (water pump seal, thermostat gasket, upper radiator hose, etc.) with
stronger and more heat resistant materials. The second recall involves the
braking system and replaces a check valve and hose leading to the brake booster.
Without this simple recall, the valve may stick under certain conditions and
hinder power-assisted braking. The third and final notice that will need to be
taken care of is the fuel system recall which replaces certain fuel lines under
the intake manifold with lines made from material more resilient to the
extremely high levels of under-hood heat associated with rotary-powered
vehicles. One can also call Mazda's Custom Service line at (800) 222 5500. With
the vehicle's VIN, they will be able to determine which , if any, recalls have
been applied to the particular car. Unperformed recalls can be taken care of,
free of charge, by any Mazda dealership.
There are a few more problems typically associated with the early third
generation RX-7's. Most apparent is Mazda's less-than-perfect painting process.
Premature paint chipping is usually isolated to the car's hood and the rocker
panels aft of the rear wheels. This problem was eventually solved when a more
traditional panting technique was applied at the factory. Another aesthetically
challenged area of interest is the RX-7's plastic interior that has been known
to peel terribly over time. This problem was likewise fixed by the factory.
Finally, when shutting the drivers side door, don't be surprised if it takes a
good slam to close fully. The doors on RX-7s are notorious for their high effort
requirements. Then again, anyone to weak to operate the door on a high
performance sports car is too [much of a pussy] drive one, 'nuff said The Test
Drive. Perhaps the most revealing analysis of the RX-7 will be conducted during
the test drive. If the car is started when cold, the engine should immediately
jump to 3000 rpm. Mazda refers to this function as the "accelerated Warm-up
system". You should think of it as cruel and unusual punishment. Gently
'blipping' the throttle should drop the engine speed to 1500 rpm. After a few
minutes of conservative driving, the idle should settle between 750 and 950 rpm.
If the car has very low mileage (less than 20,000) the engine may idle slightly
higher due to a "mileage switch" that is activated during the extended
break-in period., Another unusual quirk of the car is a noticeable fuel-related
hesitation at 3,000 rpm when the engine is cold. This is completely normal and
should lessen dramatically as the car warms up. It is also very important to
remember that with rotaries, like conventional piston engines, most internal
wear and tear occurs during cold operation. During this time, it is absolutely
imperative that driving at high rpm or under boost should be avoided at all
costs. Once the car is up to operating temperatures, the real evaluation begins.
Unfortunately, a stock RX7 is not equipped with a boost gauge making boost
testing more of a "seat of the pants" experience. It may not be too unreasonable
to bring a boost gauge and vacuum line and tap it into the small nipple on the
passenger side of the intake manifold before the test drive. The vacuum line
could then be fed under the hood and through the window to the gauge that can be
taped to the dash
To check the boost pattern, cruise in 3rd gear at 35. As the road ahead
clears, accelerate under wide open throttle. Boost levels should quickly spool
to 10 to 12 psi. Just above 4500 rpm, the boost level should drop briefly to approximately
8 psi and then slowly build up to 10 psi by redline. If boost levels are unusually
low or erratic, there could be problems with the complicated turbo control
system of the turbos themselves. Listen carefully for knock under prolonged boost [heh
heh]. Knock can be caused by running inexpensive, low octane gas or by lean run
conditions caused by clogged injector or dirty fuel filters. If detonation is
detected, lift off the throttle immediately and look for cars elsewhere. In a
rotary, if you hear a knock, the motor is already likely to be damaged. A
characteristic common with rotaries is their lack of low end torque. If the
engine speed drops below 2k, the car is essentially crippled. However, right
around 2500, the turbos quickly come to life and things start to happen,, Upon
first drives, the car may feel "jumpy" when tooled about around town. Eventually,
the driver will get used accustomed to the unique throttle management required
by the power plant. RX-7s are also known to exhibit a chronic hood latch squeak
that can drive some owners into fits of frustration. This noise can be fixed
easily, as we will see in this project series. Clunking noises from the suspension,
on the other hand, are not so readily ameliorated. Cars manufactured before May
31, 92 (check drivers side door jam) come equipped with an annoyingly noisy
upper a-arm bushing. This can be replaced with an updated version, but at a
remarkably high labor cost. The trans should shift precisely and smoothly. It is
not uncommon for rx7s to develop 5th gear synchro damage, typically cause by a
botched 2nd to 3rd gear shift. If damage is present, shifting quickly from third
to 5th gear (without letting the engine speed reduce) will result in a terrible
grinding sound. Repairing a 5th gear synchro is very expensive since it involves
removing and disassembling the tranny. Finally, check for warped rotors, cracked
wheels, engine leaks and the typical areas involved when inspecting a used car.
whew,.. ohh dangit, L there's more It is also a good idea to check the water
temp gauge toward the end of the test drive,. The needle should point slightly
below the middle temp range., Also critical to the longevity of the motor and
turbo is a nice cool down period of at least thirty seconds. Spirited driving on
the track can require up to 5 minutes of cool down to let the iron and aluminum
components of the engine recover from their thermal expansions. It is also
normal to hear the boiling and bubbling sounds from the engine after the
ignition has been turned off.