Can anyone direct me to a link pertaining to a coolant flush on a 92? Specifically I am looking for the engine block coolant drain hole plug. My Chilton manual says "if your car has it ....? but they don't show any pics of where it would be. Does the 92 have one? I know I will need to remove the knock sensors.
Any tips are appreciated.

 

Remove the 2 knock sensors and the drain plug on the radiator (lower pasenger side, plastic turn ****) and that is all there is. Should get 80-90% of the coolant out of the system just by draining those 3 places. Then you can fill the system with water, run the car, drain the system again at those 3 places and repeat a couple times or until the coolant comes out plain water.

I usually just drain the 3 places, refill and be done with it, but I do mine often.

 

FWIW, it is very important to only retighten the knock sensors to 10-12 ft.lbs and to not use any teflon tape on them. They will fail prematurely if these instructions are not followed.

 

Vette92- thanks for the reply. Sounds like an easy job. :D

 

The service manual says to flush and re-fill until the water comes out clear with bringing the water up to operating temp each time. Let cool and use distilled water for the last flush. When you re-fill after the flush, pour 2 gallons of coolant in first and then finish with distilled water. There are 2 bleed valves (brass screws) you need to open to insure you purge the system of air. One is on the thermostat housing just above the lower radiator hose connection; the other is on the left-front of the throttle body above the bypass hose. Use aluminimum foil to form a drain AWAY FROM THE OPTI-SPARK! :yesnod:

Watch the bleed valves for coolant; when it comes out in a steady stream close them both and continue to fill with distilled water. Run the engine for 4 minutes at idle. Keep the coolant level up at the surge tank. Keep an eye on the temp! If it exceeds 260, stop and let things cool down. You should clean and drain the plastic overflow tank when flushing the system. After the new coolant is finally in, put 2 quarts of a 50-50 mix of coolant in the overflow tank.

The manual also says to not "attempt any agressive driving maneuvers until the the vehicle heats up to 195 and cools down to 80 three times".

The "low coolant" light will come on after this procedure. If it does not go out after the 3 cool-down cycles, remove the cap and check the level in the surge tank. Make sure it is at the base of the neck of the tank.

 

I tried a slightly different approach. Never touched the sensors. I drained the coolant out of the radiator and upper reservoir. Then pulled the tstat housing and took the gasket off the tstat and put the gasket back in and tightened up the housing. Now water will flow even with the engine cold. I was in the process of swapping tstats so I ahd to get in there anyway. Then I disconnected the lower small hose on the upper reservoir. This is the return line. I added a small hose to it so it would run down to the ground. Left cap off. Connected garden hose in the house and started hot water running into the upper reservoir and then started the car. Now you're pushing hot water in and draining off the system. Not really a power flush. But a constant flush. The first couple of gallons coming out were silty and full of crap. Then I let it cool down for a bit and repeated this a couple of more times. Then the last time I added distilled water, like 5 gallons worth to make sure I had all the tap water out. Then add 2 gallons of anti-freeze. It pushes the water out. Then put tstat back in. Top it off and bleed air out. Maybe a little overkill but I doubt the car had ever been flushed.
Graham

 

c4crusier- thanks for the reply. Lots of good detail in the service manual that wasn't in my Haynes or Chilton manuals and I want to do the job right (or course). The tin foil is a great idea! In the past I've used a towel under the bleed valves but I'll try the foil (and towel) this time. I know about the opti since I blew a hose last year and ended up replacing the opti because of that. (A word to the wise. REPLACE those old hoses)

vms4evr- thanks for the reply. I don't think I'll need to pull the stat but its always good to hear how others do it.
:chevy

 

If the block is empty, I pull the thermostat to refill the block. It is quicker that way.

 

JINKS........ :jester

 

There are all great suggestions stated above, but allow me to throw in my 2 cents worth also. The method I suggest required a couple extra gallons of distilled water and an extra radiator hose. I do not pull the knock sensors.

Drain the radiator; take the top hose off the radiator (leave attached to the thermostat); put a spare radiator hose on the radiator and make it point to towards the wheel (away from the opti-spark); put a fresh water hose in the hose going to the thermostat and turn it on lightly (enough to fill the system); when the system is full (water comming out the top radiator hose) start the car and run the fresh water through the system until it runs clean (you may have to adjust the fresh water flow to match the waterpump); after it runs clean, remove the fresh water and pour 8-10 gallons of distilled water into the hose going to the thermostat (this replaces the fresh garden hose water with distilled water and gives it a little distilled flush); turn the car off, drain the radiator and fill with goo antifreeze; add two bottles of water wetter and the GM tabs to the pressure tank. Bleed the system as described above.