Over heating Cadillac

I have a 2000 Cadillac Deville DHS. It keeps overheating. I have changed the water pump thromostat, radiator cap and I know the fan is working. I was told it could be a head gasket. There is no leaks, no noise, No smoke and it still runs good and purrs like a kitten. Should I try dura seal and see if that seals it. Would it hurt my car? What else can I try or should I go ahead and sell it for 1500.00 it is a northstar engine and has 185000 miles.

I wouldn’t put any kind of sealer in it until you know what is going on. You may have a partially plugged radiator, and the sealer will make that worse and possibly muck up your heater core. If it runs good, you aren’t losing coolant, and your oil doesn’t look like a milkshake, it’s unlikely you have a head gasket leak. If you’re in doubt, have a pressure test done.

Would it be plugged even if I had it flushed?

Yes, the area where there is no fluid flowing won’t respond to a flush. Perhaps you need to go to a radiator shop. Given the parts replaced so far the efficiency of the radiator is suspect.

The first thing you should do is have a good shop pressure test your cooling system. Right now you are throwing darts in the dark.

What if someone did atest on the antifreeze and it changed color?

Are you referring to a test that detects combustion gases in the coolant?
If that is the case, then the engine most likely has a breached head gasket, or–more likely on that engine–a breached intake manifold gasket.

Didn’t the shop give you a verdict regarding the outcome of that test?

A bad gasket in either location can cause your engine to run hot, to lose coolant, and–ultimately–to score the cylinder liners as a result of overheating and/or burn out the main bearings as a result of dilution/contamination of the motor oil.

So does that mean I could try the blue devil or dura seal stuff?

Personally, I wouldn’t do it, but you may get some dissenting opinions.

How do you know it is overheating? Is your temperature gauge accurate? Run the heater at max and put your hand over the vent to feel the air temp. If the air coming out feels really hot, that can confirm overheating.

I know it’s over heating because you can hear it bubbling around.

In your original post, you told us that there was no noise!

When i said that I mean no noise from engine or anything like that. It sounds really good. But when you drive it and it over heats you CAN hear the bubbling from the coolant overheating, not the engine.

If the coolant is overheating, the engine is also overheating.

This engine may have been damaged very severely if you have been driving around for more than a few minutes while hearing the coolant “bubbling”.