How to Flush the Radiator
By Rob Robinette
You will need 1 gallon of antifreeze and 2 gallons of distilled (not
mineral) water. You can get the water from the grocery store for about $3. You will also
need a Phillips head screwdriver, a 2 gallon bucket, a cloth rag and a funnel.
The coolant system capacity is 9.3 US quarts (2 gallons, 1.3 quarts)
and you won't be able to drain that last 1.3 quarts of coolant so 1 gallon of antifreeze
and 1 gallon of water will give you about a 55% antifreeze to water ratio. This percentage
will give you max protection from freezing, down to -40 degrees F. If you don't need that
much freeze protection 35% antifreeze will protect you down to 3 degrees F and will
actually cool the car more efficiently.
Warning: Don't try to drain the coolant system unless the car is
really cool or you may get burned. Start by relieving the pressure by opening the coolant
cap on the engine (not on the plastic overfill tank). Then put the cap back on to minimize
the amount of fluid that will drain onto your hand when you remove the plug. The drain
plug is in the bottom of the radiator and is accessible from beneath the car (you may have
to raise the front end). There is a 1 inch round hole in the plastic engine bay floor pan
about 1 foot from the spoiler and near the center line of the car (it's the only round
hole I saw). Completely remove the drain plug, put the bucket in place and then remove
both coolant caps to help the system drain. Warning: Antifreeze smells
and tastes great to animals and it will kill them, don't leave this stuff lying around.
Take it to a recycling station.
Flush out the system by pouring in about a half of a gallon of
distilled water. Wait for it to drain and reinstall the plug. If you want to really flush
out the system then fill it with distilled water, replace the radiator cap and run the
engine for about 3 minutes with the heater on full hot and then drain it again. If you do
the double flush you will need another 2 gallons of water. Add the water and
antifreeze to get between 35% - 55% antifreeze. I recommend alternating between the two
fluids because you can't be sure how much fluid will actually be needed to fill the
system. You can minimize the air bubbles in the system by gently squeezing and pulsing the
large diameter coolant hose that runs by the right side of the intercooler. Check the
fluid level in your overflow tank (white tank near the front right wheel). The only way to
replace it's fuel is to suck the fluid out or remove the fender wheel liner and take out
the tank. I just added some water and coolant to get the level close to the F line on the
IMPORTANT: You must "burp" the coolant
system. Run the car for a about three minutes (don't drive it yet because you may be low
on coolant) and shut it down. Put a rag over the engine coolant cap and open it up, pulse
the big coolant hose, and top it off. You will need to do this several times. The first
time you drive it take some water with you because you may get the "Add Coolant"
buzzer and you don't want to drive the car for more than about 30 seconds with the buzzer
on. Remove the radiator cap and top off the coolant level before you drive the car for the
next three drives and you will have a well purged coolant system.
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 iterations:
Replace air separation tank (black plastic) 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 my car was at MazMax here in Houston last fall (turbos were being pulled), the
mechanic gave me this tip which is fantastic. Remove the top coolant hose from the
throttle body (is in the rear near the firewall) when refilling the system. Today
I did a cooling and heater system hose replacement job, along with eliminating the coolant
separation tank (installed the 86-88 pressure cap neck). I removed the top hose when I
started filling the system. This was the first time in 6 years that the system almost took
the full amount, about 8 quarts. After filling, replacing the hose, and running the engine
for 2 minutes, it only took about 1 pint more. Then I drove the car until fully warmed up
and let it cool down; it then took about ¼ cup more. During this the overflow tank was
filled ½ way of course.
Chuck 93 R1
The most important tip is to make sure
the drain plug still has a rubber gasket/washer on it before putting it back in. I did not
know this plug was there, and had I not seen it in the pan I had drained the coolant into,
I would have never known any better. The washer must have stuck to the radiator and then
fell off as the coolant was draining. Nearly a disaster.
Did you take out the block drain plug, located on the mid-housing, just above
the oil pan rail? If not, you left a lot of fluid sitting in the engine block.
The plug is just a scaled down version of the oil drain plug - straight threads,
with a crush washer. I can't find it mentioned anywhere in my '94 shop manual,
so I just tighten it down by feel. On my car, there is a blind tapped hole next
to it, with nothing in that hole.
The coolant drain plug on the engine block