Rep Power: 452

I am wondering about this since I burned the **** out of my hand today by a radiator cap blowing off the radiator and hot *** coolant blowing out.

Anyway, I was doing a radiator flush on a 1997 toyota camry today with the wynns radiator machine (which I dont like) but anyway, I did what I usually do with any car is flush and that is I set the heater on full blast to circulate all the coolant, then remove the cap and put a vacuum on the radiator and overflow resovoir to get out all the coolant out. Once I finish, I turn the machine to the pressure and start adding coolant to the radiator and overflow tank slowly. I do this as to make sure I dont make a mess. And I dont put the nozzle directly into the radiator, i set it above it and let it slowly come out.

Well I did that today and after I got about half of a gallon of coolant or so in the radiator, once it fills to the top, it starts slowly blowing out, like a overflowing toliet does, the coolant would drop back down in the radiator, then come up to the top and overflow out the cap. it did this several times, and each time I kept topping off. Well after it kept doing this, I put the cap on and went into the car and noticed that it was starting to overheat. the needle was almost to the red line. SO I quickly opened the hood and I removed the radiator cap and as I did it, the ***** blew off and hot *** coolant started blowing out all over me and the car. SO I turned it off and had the manager come over, who ended up topping it off and when I turned the car on, the temp was back to normal.

Now can anyone explain why this all happened. Including why the coolant started overflowing out of the radiator in the first place, but to find out it wasnt even full?

I am assuming that the cap blew off once I loosened it because of the added pressure in the radiator from the car overheating, which at the moment my stupid *** self didnt think of. Yes I made a stupid mistake (thats why it says to never remove the cap when hot), but I still want to know what happened.

Also, before this happened, I noticed coolant kep sitting on top of the radiator which to come find out after all of this there was a 6 inch crack in the top of the radiator. I am not sure if this had an effect on what happened, but maybe someone can tell me.

I have never had this problem on any other car as each time I do it, the radiator fills fine and I have no problems. But this time I did. We encountered another car do the same thing that was overheating and the cap blew off because the fans werent coming on, so I am thinking there may have been a problem with the car or maybe something I did. I am trying to figure this out so I dont make the mistake again.

 
Rep Power: 452

Well I talked with a teacher today who said more then likely there was a big air pocket in the radiator when I was filling it up and thats why the coolant kept going in and pouring back out. He said that crack in the radiator was probably sucking in air when I was filling it up.

But anyway, I learned my lesson as to never ever again pull off a radiator cap when a car is overheating.

 
Rep Power: 262

Yep, that would be a good guess. Since you pressurized the system open you introduced a compressed air bubble.

 
Rep Power: 0

My vote is on an ait bubble as well.