dizwiz24

I had a hose blow out on my radiator and am going to flush/fill the cooling system and replace it with a 50/50 mixture of antifreeze/water.

I want to flush it first. Does anyone here have any special tips/advice?

Dave

dizwiz24

I have a 93 LT1 ZF6

vetteweiser

Hell, I considered blowing my upper radiator hose the flush
Seriously, I did

tempest

when i did mine this summer, i drained the system, refilled with water, ran the car until the t-stat opened, cooled down, and repeated process about 10 times. when i drained the system i always took out both knock sensors to drain as much as possible.

refill with 50/50 using distilled water only, and all set.

also, some have used the Prestone flush kit with success. i just bought one and plan on using it before wintertime.

wildman378

when you guys drain it and put water in and run it for awhile are you jsut using water out of the hose for that step or distilled?

tempest

i used tap water until the final flush, where i used distilled water for that.

onedef92

You may think I'm daft, but when I flushed my '92 LT1 coupe, I opened the radiator petcock and removed the radiator cap on the black coolant tank on the passenger's side of the engine bay.

I then took a Shop Vac and attached the hose to the vacuum's BLOWER port and put it over the radiator coolant tank. The forced air pushed ALL the coolant out of the block and radiator without having to remove the knock sensors.

I then did my flush-and-fill, evacuated the system again using the Shop Vac, refilled with the proper mix of coolant/water, opened the bleed screw, let the engine reach operating temperature, and inspected for leaks. Voila!

Pony_Express_Driver

Well tell me where the damn thing is so I can drain mine! 92 Vette

tempest

the petcock? it's on the lower passenger side of the radiator.

onedef92's idea is pretty neat, but if you wanted to do it "by the book," drain via the petcock, and remove both knock sensors to get most of the coolant out. draining just the radiator gets out only about a quarter of the coolant in the system.

when you reinstall the knock sensors and IF you need to use sealant, use just a thin smear. no teflon tape. must torque to spec (forgot the number - post back if you need it).

c4cruiser

Removing the knock sensors are the best way to get all of the coolant out. It's sort of a messy job, but worth the effort especially if the old coolant has been in there a long time. Use some anti-sieze compound on the threads and tighten to 14 ft-lbs. As stated, don't use teflon tape or sealant as the body of the sensor provides the electrical ground to the unit.

Tap water can be used for the flushing (do it 2 or 3 times) and the final fill is to pour in 2 gallons of coolant followed by 2 gallons of distilled water to fill the system. You could pre-mix it but the system capacity is 8.2 quarts anyway.

Remove the overflow tank and clean it out (mine had over a 1/2" of gunk in the bottom and replace it and when you are done with filling the system, add enough of a 50-50 mix to the bottle to bring the level to the "Cold" mark.

ron92Z07

I am getting ready to do this within the next week or so and was curious if you guys recommended replacing the knock sensors. My car has close to 99000 miles and I figure while I am there I might as well replace the sensors. What do you guys think?

Ron

Strick

Here is the way I do mine and I haven't found a better way to completely flush the system and refill.

https://www.corvetteforum.com/techti...=222&TopicID=2

kwd1

I only did one water cycle before the final fill. It came out clear. I used the shopvac trick with the radiator and knock sensors out. It blows about 1/2 a quart out. I used distilled throughout. My area has HARD water, so it wasn't worth the $5 to risk the deposits.

Don't forget to run your heater when you have the cleanout water in to get the heater core.

I used teflon tape and haven't noticed any ill effects yet.

tempest

a friendly warning, when you do notice ill effects it may be when you put a hole in a piston. the teflon tape will attenuate the knock signal and it may not work when needed the most. hopefully you will hear the knock before it does anything bad.