FLOW RESTRICTIONS
Other potential issues on the Fox Mustang’s cooling system concern the location of the upper radiator hose, which, due to its high mounted location,
can cause vapor pockets to form which in turn affect coolant circulation. And especially on the likes of ’87-’93 GTs equipped with air conditioning,
a smaller frontal grille area and the mounting of a condenser in front of the radiator impedes flow to the latter. If you have one of these cars or are
thinking of buying one, pay particular attention to the condition of the cooling system components.
Although this might seem like a lot of things to go wrong, Fox Mustangs in general are very reliable cars, and as long as its related components are
properly inspected, maintained, and replaced as required, you shouldn’t likely have any issues with the cooling system.
“FREEZE” PLUGS
These discs fill the holes left through which the casting sand was removed when the block was
cast. For what it’s worth, they are actually sand core plugs. Because they are usually the first thing
to give when the coolant freezes, they’ve become know as “freeze” plugs, and people mistakenly
think they’re a safety valve for frozen coolant.
These steel plugs are usually hard to access and can become an aggravating problem if they rust
out and begin leaking.
When replacing core plugs, the easiest way to remove the old ones is by using a punch and a
hammer. Place the punch on the outside edge of the plug and tap it. Usually, one side of the plug
will turn inward to the block; you can then pull it out using pliers. Even if it falls into the block it
won’t go far, so retrieving it won’t be an issue.
When installing new core plugs, it’s a good idea to use replacements made from nonferrous
metals such as brass (often used on marine engines), which won’t corrode, or at least paint the
exposed surface with rustproof paint. Clean the sealing surface on the block with sandpaper and lacquer thinner — any dirt or debris can prevent a
proper seal. Use a nondrying gasket sealer on the sealing surfaces. Brass is softer than steel, so drive them straight in with a wooden dowel — don’t
hammer on them directly.
THERMOSTATS
A common hop-up used to be running a 160- or 180-degree thermostat, cooler
than the factory 192-degree thermostat, to fool the EEC-IV computer into thinking the
engine was still cold. This would signal the injectors to add more fuel, enrichening the
air/fuel mixture.
The downside of this is that there are more accurate ways to map fuel curves, and
too much fuel can wash down the cylinder walls, accelerating wear, fouling the plugs,
increasing fuel consumption, and creating poor throttle response and other driveability
problems.
Besides, for maximum efficiency, you want the intake charge cool, but the block hot.
While a cooler thermostat can work on highly modified cars that generate lots of
heat, on your average street car, they cause more problems than they solve, so sticking
with a stock 192-degree unit is best to ensure adequate antifreeze circulation through
the radiator and jacket passages, as well as an optimal air/fuel ratio.
SOURCES
42 FOXMustangMagazine.com
DaSILVA RACING
960 Brock Rd.
Pickering, ON L1W 2A1
Canada
(905) 837-7700
www.mustangtoystore.com
LATEMODEL RESTORATION
400 Jan Dr.
Hewitt, TX 76643
(866) 507-3786
www.latemodelrestoration.com
PERFORMANCE PARTS INC.
13120 Lazy Glen Ct.
Oak Hill, VA 20171
(703) 742-6207
www.performancepartsinc.com