Bad Rad?

Replaced:
Water Pump (& Timing Belts)
Upper Hose
Thermostat
Radiator Cap

Car will spike high temps only at highway speeds and usually drops back down to normal after pulling off and letting it idle a couple minutes. It is boiling out of the overflow and then when I crack the cap there is no steam or even pressure built up. I end up topping it off but it just keeps on boiling out.
I replaced the upper hose after on the way home I pulled off with it hot, popped the hood and saw that it actually sucked the hose flat. I am leaning towards a very plugged radiator right now. There is a lot of rust deposits I have flushed out previously when I flushed it. I am thinking the fins are too plugged for the water to flow and get cooled.
Any other ideas? I may take the thermostat out tonight yet and see if I can atleast get it to flow and stay cool enough to drive.

Is your radiator cap rated at the right psi? and is it leaking from anywhere else? I had a problem with it leaking into my overflow and noticed that my cap busted replaced it and fixed the problem?

Cause i have replace my whole system so far replaced the radiator cap, radiator hoses, and thermostat, and its either the thermostat or the radiator cap....what happens when you turn on the heater?

Quote:

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Originally Posted by bmxmike

Is your radiator cap rated at the right psi? and is it leaking from anywhere else? I had a problem with it leaking into my overflow and noticed that my cap busted replaced it and fixed the problem?

Cause i have replace my whole system so far replaced the radiator cap, radiator hoses, and thermostat, and its either the thermostat or the radiator cap....what happens when you turn on the heater?

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13 psi cap... it was just replaced not long ago- when I started trouble shooting this problem.

No leaks that I could find... I have had it in my garage running just trying to find any. Ran it to get it hot and pulled off and the only thing I see is it boiling out the overflow.

Heater... I do get heat. I thought it may had been the core but I do get heat and it does help pull heat back out of the system and cool it back down.

It just seems like it isn't flowing through the radiator at all... I still plan on pulling the thermostat to see if it will stay cooler at least until I can trouble shoot more.

Well it is still boiling over and getting hot without the thermostat... guess I am getting a radiator tomorrow.
It wasn't as bad, as with the T-stat in, but it still got hotter than it should and it did recover faster. Atleast I should be able to drive it without damaging the head or anything.

Well the radiator fixed it... so much so I got nailed doing 94 in a 55 zone about 10 minutes after I had it finished. Life sucks... :roll: