radiator blowout problem

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Sep 15, 2010 | 05:58 PM

cheapjeep

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radiator blowout problem

I have a 1979 f150 with the 300 inline 6 and the original rad in it burst about 2 mos ago and I put the biggest rad in it for the model from a 460 and today it just burst again and it's a fairly new rad so I knew it wasn't all rotted out so could it be a stuck thermostat...and I always thought the pressure release in the cap was supposed to be the failsafe?

Sep 15, 2010 | 08:53 PM

4x4 Bart

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From: Middle TN

This is really strange that it would happen twice. The spring in the cap is working right?

The only other thing I can think of is, newer radiators are thin and much more fragile than the originals. I do not like to bolt them up tight to the radiator support. There could be enough twist in the support like on a ruff road or driving off a curb, to possibly damage a radiator. I only use two bolts at the top and I use a lock washer and don't tighten them completely but just till they touch the lock washer. I can grab the bottom of the radiator and move it a little. You could use thick rubber washers and do the same thing. This is not a new idea, Model A fords mounted the radiator on springs so it could flex.
I did this after I had a one year old radiator burst for no reason.

Sep 16, 2010 | 04:37 PM

BigBlue88

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Joined: Jul 2004

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From: Northern Virginia, USA

Might be a stuck thermostat. Easy enough to replace. Just two or three bolts. Did you replace the radiator cap at the same time? If your water pump was bad and not circulating, that could cause a radiator-bursting overheat condition as well. If you had a slow leak somewhere which was draining the coolant down below the level of the water pump, that could also burst the radiator.

My truck had the pinhole leak/drain-down problem and burst the radiator because of it. Tightened the hoses, and fixed the burst top-tank seam with JB Weld.

Sep 16, 2010 | 05:07 PM

Big_Dom

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From: Great Falls, MT

its got to be the T-stat.

Sep 16, 2010 | 05:40 PM

4x4 Bart

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Joined: Feb 2007

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From: Middle TN

Wouldn't your radiator just boil over and puke out the overflow tube if your thermostat stuck closed? I have never seen a radiator burst from over heating or boiling over. I have seen a radiator burst from being completely stopped up but he says its a new radiator.
Doesn't the radiator cap control pressure?

Sep 16, 2010 | 07:13 PM

BigBlue88

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Joined: Jul 2004

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From: Northern Virginia, USA

My radiator already had a pinhole leak at a weak seam. OP never said if he'd changed his radiator cap, which absolutely would limit system pressure by venting/burping off steam.

Sep 16, 2010 | 08:28 PM

southernboy0122

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Joined: Sep 2009

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From: Goldsboro Nc

if his t-stat was stuck closed his truck would overheat quick and i would think it would cause engine damage, before the radiator bursting. it is strange, i would replace the cap. they are pretty cheap, i have seen some cooling systems develop air pockets and over pressurize like a mother.