ok, i have a 79 bronco that is strictly an offroad beater. just muddin and offroading because it will never pass inspection and i dont want to have to put money into it to make it safe with historic tags. yesterday me and my friend were just racing in a field. my truck was running like a champ. it has a 460, c6 auto, 3/4 ton rears, 4x4, 38" ground hawgs, and 4.10 gears, i have a block heater on it whenever its sitting and i take it off before i use it. last year when i ran the truck in the gumboro mud hop the thermostat started to stick closed so i just took it right out and never put a new one in and the water pump was fine. i beat my friend like 9 times then all the sudden we started another race and when we got to the half way mark the radiator litterally blew up and popped up the hood and all, no overheating or anything. i have the factory gauge and a mechanical gauge both read low because of no thermostat but i figure it as normal for this truck now. motor and tranny are stock. i just stopped and shut her down. i'm going to replace it but i want to fix it before i blow another one. what do you think could have caused this?

 

A blown head gasket.

 

thats what i was thinking. i started it up today it ran beautifully and there was no smoke or water at all coming out the exhaust and the engine wasnt leaking any antifreese except from the radiator hoses. i cut the exhaust out about 4 ft. from the manifolds and angled the pipes outwards and down a little bit. i cleaned the engine up this morning to make sure it was all dry. no leak what so ever when i started it. the motor came out of a friend of mines truck and it literally only has maybe 30000 miles on it. he bought his truck new only to go to and from church and the store. but his body rotted so he sold me the motor. its all original. even has the factory carb on it but i rebuilt that. are there other possibilities. could it just have been my luck or just some random thing to happen.

 

Same thing happened on a sentra i had when autocrossing it my cap wasnt letting excess pressure out of the radiator as it should and the whole upper tank exploded actually denting my hood a bit, as soon as i replaced the radiator and cap everything was A ok

 

i didnt even think of that until you mentioned it. i'll check it and see what i come up with thanks.

 

alright well the cap wasnt any good whether or not it was the cause. the slide where the spring and seal sit was rusted solid and i couldnt move the seal. i replaced the cap and radiator. ran it for about an hour and a half with no problems. i guess i'll have to see what happens later. i'd kinda hate it if it was the issue though because a freakin $3 part costing you $300 but its an easy cheaper fix than if its something else like the head gaskets. i guess i had better pray thats all it was. thank you guy's appreciate the help.

 

Sounds to me like you found the problem.

 

Running without a thermostat can cause overheating also. Some form of restriction needs to be in the way to slow the coolant enough to pull enough heat out of the motor.

But sounds like your cap was the main problem.

Adrianspeeder