Chevy Trailblazer Brakes Contaminated And Engine Overheats

My 2007 chevy trailblazer all 4 calipers are locked what could be the problem?

Well when you have a problem like that, usually brake fluid contamination is the cause.

What would be the fix?

If contamination is the cause, unfortunately the only way to repair this problem is to replace every single component that comes in contact with brake fluid. You'd be looking at replacing the master cylinder, ABS unit, all four calipers, all four brake hoses. This will be very expensive to do.

I did just replace the rubber seal on the cap it was broken and it blew up and was like that for a couple of weeks. What would contaminate it though?

If the rubber on the cap expanded, that is a for sure sign of contamination. Someone had to add a different fluid than actual brake fluid to the system to cause this.

Do you have your oil changed anywhere, or do it yourself?

i do all the work myself and if someone did do that how long would it take to contaminate?

It can take a couple of weeks to fully contaminate the system and start expanding rubber hoses and seals. Visually the rubber hoses look fine no sign of expansion.

Yes, you normally can't see any problem except for the cap on the master cylinder.

Unfortunately, you do have contamination, so everything will need to be replaced.

I have a 2003 chevy trailblazer v8 5.3. It is overheating and loosing coolant and the heat goes from hot to cold. Is this my thermostat or my heater core?

It's actually probably neither of those things. If you have a leak, it really needs to be seen to be diagnosed. The water pumps on the V8 engines tend to go out quite often, so that could your problem. I really doubt it is a heater core. If the water pump is bad, the thermostat is part of the new assembly and would be replaced with a new pump. Otherwise, you could be looking at leaking head gaskets, a radiator or hose that is leaking, or similar.

My gage fluctuates up and down also. When i put water in radiator the water bounces up and down like the thermostat is sticking.

Yes, that will happen when you experience a leak and/or air getting into the system. Even if the thermostat is sticking, it would not cause a leak.

If the motor gets hot does it come out of the overflow hose by the coolant tank this is where the leak is?

Ok, well like I said, a problem like this really needs to be looked at in person. I can only give you suggestions. If you think it's just the thermostat, then replace it and go from there.

Thank you for your suggestions, i will have it looked at.