KLLRVET

Anyone ever use the Prestone Cooling System Flush kit on an LT1? I am talking about the kit that has the coupling that attaches to a heater hose. Does it work okay on these cars? I have heard that you should NOT use them one LT1's because of the reverse flow? Anyone know for sure?
Thanks in advance,
Tony

KLLRVET

TTT

BlackRocket

Don't do it !!! I ran a prestone coolant kit on my 91 L-98 and the car started missing radically. I shut off the water as fast as possible and then shut off the motor. I started the motor again and it still was missing pretty bad. I shut it off again and let it cool off. It ran normally after it cooled down. Since I was about a few weeks away from building the motor into a 383, I decided to try it again. After the motor got a little warm, once again it started missing very badly. I don't think it did any damage, but I will never use another prestone coolant flush kit on any of my cars again. There's something about running cold 65' water into a 200' engine that is inherently wrong. My advice, just drain the radiator, refill with distilled water, drive 10 miles with the heater on, repeat, and refill with istilled water and appropriate coolant mix.

Good Luck ~ :chevy

93 ragtop

I used it on mine. I inserted the screw on hose fitting in the heater hose where it is tee'd for the TB hook up. I flushed it until it ran clear.

merrick

No, not on an LT1. But I like the drain/refill flush method too. If you use the flush kit do it on a cold engine. To properly drain an LT1, you have to remove the two knock sensors.

YLO Z06

GM Factory Service Manual says do NOT use a flush kit on the LT1/4. Just drain and refill the coolant system. To drain the LT1, unscrew the radiator drain plug located next to the lower radiator hose connection on the radiator. It is a plastic screw that you undo by hand. Also the manual says remove both knock sensors in the block, but I didn't do that step.