Coolant/Cooling Issue - Please Help

I bought a used 96 Blazer 4x4 LT about 2 months ago with about 107k miles. Everything has worked fine until yesterday. (Note: At this point the color of the coolant is Brown with sludge right under the rad cap) The temp redlined. Come to find out I am really low on coolant. I add more coolant and it works the rest of the night. At this point I realize I need to flush the coolant and replace with new.

Next day I leave for work and it redlines again. I go buy a new thermostat and replace it and it works for about 10 miles and the heat goes cold, but the temp stays in acceptable ranges fluttering up and down from time to time. I take it to a dealership who for $54 flushes out the coolant and replaces with Green new coolant. After doing this the tech tells me that someone has used ALOT of stop leak in the cooling system and its possibly clogged up. Driving it home it does the same thing, no heat but temp stays in acceptable ranges fluttering up and down.

I also got a rushing water noise inside the truck when stopping and starting *some* times before this happend. It sounded like it was coming from the area where the core is

So my question is this.

Could the tech mistaking the stop leak for dex cool gone bad?

Why did it work fine for 2 months and all of the sudden go bad..

Can I just get it flushed a couple of times..

Is it safe to drive ?

Chris

I bought a used 96 Blazer 4x4 LT about 2 months ago with about 107k miles. Everything has worked fine until yesterday. (Note: At this point the color of the coolant is Brown with sludge right under the rad cap) The temp redlined. Come to find out I am really low on coolant. I add more coolant and it works the rest of the night. At this point I realize I need to flush the coolant and replace with new.

Next day I leave for work and it redlines again. I go buy a new thermostat and replace it and it works for about 10 miles and the heat goes cold, but the temp stays in acceptable ranges fluttering up and down from time to time. I take it to a dealership who for $54 flushes out the coolant and replaces with Green new coolant. After doing this the tech tells me that someone has used ALOT of stop leak in the cooling system and its possibly clogged up. Driving it home it does the same thing, no heat but temp stays in acceptable ranges fluttering up and down.

I also got a rushing water noise inside the truck when stopping and starting *some* times before this happend. It sounded like it was coming from the area where the core is

So my question is this.

Could the tech mistaking the stop leak for dex cool gone bad?

Merlin says
Yes and no, Since you just bought this truck 2 months ago, you don't know how it was treated or what was done to it....point in case..cooling system sludged up and the possiblity of a clogged heater core and maybe a leak somewhere.

Why did it work fine for 2 months and all of the sudden go bad..

Merlin says
Is this the first time you have tried to use the heat? Maybe it has been leaking over time and now its low enough on coolant to present a problem.

Can I just get it flushed a couple of times..

Merlin says
There is a procedure using a Prestone acid type cooling system flush that I have used with some success in cleaning the cooling system and heater cores on these trucks...if it does have stop leak in it, most likley you will have to replace the heater core and maybe even the radiator.

Is it safe to drive ?

Merlin says
I would not recommend driving a vehicle that is overheating unless you have really comfortable shoes or a large bank account to pay for a damaged engine

Chris


Hope this answers your questions