I have just replaced my radiator on my 1999 Tahoe. I also put all brand new dex-cool fluid in the new radiator. My question is Do I still need to flush the system? The warranty on the radiator states that I do, but I guess I am not seeing the point if it is all brand new. Thanks, for any help and I am glad I found this forum for help, I used to have all my work done at shops now they are getting too expensive and not really trustworthy anymore.

Avidmuskie

 

Well, basically, the water in your radiator (and the dirty particles that come from rust and all...) is only about half of the circulating water in your engine.
Its like cleaning out a sink after preparing lettuce. The lettuce leaves bits of sand in your sink. So if you drain the water some of the sand goes through the drain, but some remains in the sink. So you use additional water to clean out the remaining sand untill its all gone.

Its kind of the same for your engine. Flushing means using water (and additional stuff) to clean out your engine from rust, dirt particles and anything els that could clog your water circuit. Thats why , from time to time , you just remove the lower hose and let all the water out. Then you fill it up with water again, drain it again and check the water. And you keep repeating this untill what comes out is exactly the same as what goes in.

so when you say "its all brand new", this is only partly true, because the waterdepartment of your engine is still the same (unless you swapped an entire engine too?).
Doing only half the work is almost as effective as not doing anything at all , from time to time.

 

Muskie,

Hopefully this message finds you "flushing". Be sensible and use common sense when considering flushing and the frequency in which you do it. The bottom line is, flushing your water system, when done correctly is pretty time consuming, but I consider it a necessary part of preventative maintenance IMHO.

Like the previous poster stated, your radiator is only one part of your vehicles cooling system so there are other components that "gunk" your system up.

I live in the Phoenix area so I make it a point to "flush" atleast once a year, sometimes two when I forget to keep track, but especially before the summer begins.

But along with flushing, make sure that your other components are in tip top shape including your water pump, thermostat, hoses, fan clutch and your belts (should your fan be belt driven.) I spent a little money for my 89' and bought a 4 core aluminum radiator and it has really made a difference in the Arizona summer. Hope this answers any questions. Happy wrenching!

 

If it isn't too late, flush it out before circulating the system through the new radiator.
It sounds like it's too late for that but better late than never.