1998 Blazer Heat Problem again

I've got a 1998 Chevy LT Blazer with no heat. The temp gauge reads about 200. Cold air comes out when I put the heat on.This happend six months ago. I had the radioator flushed, radiator cap and thermostat replaced. This time around the coolant overflow tank looks rusty. Is this the sludge problem I keep hearing about? Is there anything I can do to keep this from happening again. Thanks, Mike

what is the sludge problem? i was thinking of buying a 98+ blazer, is this a major problem i should be watching for?

I've seen on the net that the Dexcool antifreeze has been causing issues. Do a search on dexcool with google. Basically the antifreeze turns to sludge in your engine causing problems.

I've seen this too. This is the orange colored "extended life" coolant that's supposed to go 100,000 miles without changing. From what I've seen, the thing to do is drain that stuff out, flush like crazy, and replace it with the regular green colored coolant. If you're already experiencing problems, you may want to do several flushes until the drained coolant looks clean. (As in, flush, replace, drive for a while, then drain again and check if it looks clean or rusty.) I have a 96 Blazer that hasn't had any problems yet, but I'll be flushing this month.

I had that problem in my 95 Blazer. Wound up being the head gasket. It had green antifreeze in it at the time and it turned all rusty colored. Maybe someone could tell me but I have heard from a few mechanics now that tell me running the green antifreeze in these trucks is a no no. Something to do with the acidity? Let me know. Thanks.

Holy 7 year old thread batman.