Hi Guys
I am looking for advice on the best and proper way to flush my cooling system. I've read about many different ways and figured as always I would get the best advice from the forum. I'm sure there are posts here , but I could not find them. Thank you!!

 

I belive yours has one knock and one hose remove both and flush well and the radiator drain. I would put back a new knock torque is important. Good time for new hoses if needed.

 

Drain the radiator. Then pull the knock sensor on the passenger's side. You may not get coolant out the hole, it may have a thin cover of rust over the opening. Take a screwdriver an slowly poke it in the hole. BEWARE THAT THE COOLANT WILL COME FLOODING OUT.....so be prepared. Then remove the block plug on the driver's side and drain that side. Run water thru the radiator so it flushes the radiator and also comes streaming out the two openings in the block

Put the block plug back in and the knock sensor back in. Close the radiator petcock and fill with coolant. With the 85, you need to jack up the front end as high as you can get it and place on jack stands or blocks under the wheels to burp the coolant system. Start the car and let the coolant circulate and fill the radiator as the system heats up.

 

Yes forgot to mention the knock and coolant. Turn your head a keep your mouth shut.

 

agree with above. first rad, then ks. both are like a giant douche. expect to get wet. i was COVERED my first time and my wife was like....well..you know.

on my 85, i used a funnel and directed the squirt as best i could downwards to the catch tub. wear old clothes!

as for torque on the ks, its 15lbs ft and just go easy on the sensor.

i never replaced mine, i used pipe dope on the threads, just on the bottom few, not too much, all is well.

if u have the dough replace the ks and buy the gm paste.

to unscrew the ks, , you need to first pinch the plastic wiring plug but placing a thumb and pointer finger on the flat edges while pulling. its sort of oval shaped. you pinch the long axis, which flares the short axis, and you can pull the plug off easy. then you will need a relatively deep 7/8" socket to back out the ks. go easy. hold the socket perfectly perpendicular to the 45 degree angle that you will see from teh block. you don't want it slipping and damaging the unit, its an acoustic microphone basically. be easy on it if you plan to reuse it. i did. and you will need to remove a couple small bolts along the oil pan rail. not bolts that hold the rail on, but bolts that hold the protective shield in place. i think they are 10mm.

it will make sense when you look at it. good luck and report back! take a picture of how nasty your coolant is.

oh, and the petcock (threaded drain plug) on the rad is the rear, bottom, passenger side.

 

New knocks come with the right dope on it I would buy new why would you put back 20 plus year old cheap parts.

 

Is the block plug on the drivers side in the same location as the KN on the passenger side. Thank you again

 

85 does not have one on the driver side.

if u r a z51 car u will have the oil cooler which is on the driver side opposite the knock sensor with coolant hoses running to and from the cooler which is between the filter and the block. u could unplug the coolant lines. i wouldnt. just drain replace petcock, drain block via the ks. refill. repeat if your fluid is still dirty.