So yesterday I got home after driving about 30 miles and shut the truck off got out and when i walked around to the front of the truck i noticed fluid pouring out from underneath. I popped the hood and my radiator was overflowing out from under the radiator cap. I just had an oil changed and the guy said he topped off all the fluids I thought he might have overfilled it so I checked the coolant bottle amd it was filled to the brim with only a little air pocket at the top. So I took a little out. drove the truck the next day no problems. Then yesterday the temp guage started reading over 210 and got to about 230 but after a minute or so went back down to about 180. When I got home its was boiling out from under the radiator cap again but levels looked fine.

Would a bad radiator cap cause all this?

here are some pics:







The fluid in the coolant look really clear almost like its 100% water could that also be my problem?

 

a few thoughts....
1. coolant should not be clear water, but should be a 50/50 mix and be green. clear water will boil at 212 and standard pressure. straight water WILL work for the time being, so don't waste money on new coolant, as you may have another problem and have to drain it out anyway.

2. your radiator cap should not be leaking, but instead letting excess pressure bleed of into the overflow tank. check your overflow port, hose and tank. it should be clear and allow water to flow in/out. also check the gasket on the rad cap and its seating surface in the neck. if any doubt, replace it.

3. i hate to mention this, but you might have a bigger problem. a blown head gasket will put compression pressure into the water jacket, and it will over pressure the cooling system, forcing water out of the block and out of the rad. this leads to overheating, as you described. check your oil for signs of coolant and file this thought for if you don't find an easy solution.

 

overflow port is fine along with the hoses. Thats actually how I drained some excess out.

I will check the gasket on the cap.

It never reached 212 the first time it boiled out. kinda makes me nervous, but on the other hand I am 100% positive the only place the water was coming out of was the radiator cap. I checked all hoses and through out the engine bay for any sign of another leak.

Man I really hope its not a blown head gasket. I just bought this truck about a week ago.

Wouldnt a blown head gasket show it self all the time? I mean it wouldnt run 70mph down the interstate without over heating if the head gasket was blown would it?

 

don't panic yet, just keep it as an evil thought to come back to if necessary.

if temp sensor in the upper intake manifold is at 200-210, then block temp down around the cylinders will be higher. a working cap thats holding pressure will increase your boiling point by a lot, and allow straight water to be temporarily used.. a non-working cap and straight water is a no-no.

replace radiator cap, maybe t-stat, drain/refill radiator with fresh water. don't waste money on antifreeze until you've got the problem solved. drain radiator with funky drain on drivers side. turn it counter-clock about 1/4-1/2 and then PULL out on it.

 

Ok i'll grab a radiator cap tomorrow and start there. If that doesnt help ill drain and refill it. Then i'll try a new t-stat. Hopefully that will take care of it.

do you think a bad water pump could cause this?

 

no.

the problem is either cap not sealing/holding pressure, or excessive pressure in the system.

 

If your leaking fluid from you the cap it's the cap. Over fill will go into the over flow tank.

 

ok thanks guys. So do you think the slight over heating could be coming from the loss of pressure due to it coming out of the cap?

 

could be...

 

ok that gives me some hope lol.

i figured the combination of water and bad cap was the root of the problem......lets hope