Help...Blown Radiator!

fivefix

fivefix

Member
I was breaking in my newly rebuilt engine on my 1930 Tudor and hit disaster at 132 miles. I noticed a small amount of antifreeze dripping out of the radiator fins (I was driving with the hood off) and a little steam exiting as if a tube was leaking. I immediately headed for home and the bottom seam of the radiator reservoir blew as if it was pressurized. Steaming hot antifreeze blew everywhere. I have melted solder on the radiator and engine and quite a crack in the seam. I was running 50/50 Prestone mix, changed the oil at 100 miles, installed a Vintage Precision thermostat housing and am running on the original radiator. I pulled the thermostat and it opens fine at 180 degrees. We cranked the engine and the water pump rotates as it should. We also added water to the radiator and the overflow is not obstructed. I torqued the head nuts after an initial engine warm up and cool down and after 35 miles.

It's 85 degrees in Iowa today, mostly cloudy and I was driving between 35 and 45 MPH with most of the miles at 40 MPH.

Attached is an image of the blown seam.

What did I do to cause such a catastrophic failure of the reservoir seam? If I was losing a substantial amount of fluid, (no puddles anywhere) could the engine overheat and build up enough pressure to blow?

Thoughts?
 

Attachments

  • Blown Radiator.jpg
    Blown Radiator.jpg
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a comon mistake is installing a new motor and using an old radiator with the possibilities of not having 100% good flow. new radiators are not cheap but can prevent the motor from running hotter than it should or having them fall apart
 
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When you put water in it with the thermostat did you wait for the thermostat to open
to add more water to the system? Or did it just have the initial fill.
 
"Key Word, "Thermostat" Why ??"

Same question I had - I drove mine all winter with temps down to 20 below and I can assure you they get warm fairly quickly without a thermostat. Just another thing to go wrong (or install backwards)......
 
Fivefix,

Some thoughts on this.
In your neck of the woods I can understand why you want a thermostat most of the year. If your overflow pipe is clear, even with a stuck thermostat it seems unlikely that you could build up enough pressure to blow the seam.

Not knowing the history of your radiator and any prior repairs here is somthing I would take a close look at. If in the past the radiator was repaired and the top tank and header were not properly cleaned and tinned then you could have a weak seam. If you put the thermostat in the upper hose you have lost some flexibility and the engine vibration or torque will put a bending/twisting action on the top inlet casting and flex the seam until it fatigues. Years ago when I worked in my dad's radiator shop I can't tell you how many tanks I pulled that had very little solder holding them on due to corrosion. One of our best friends were those one shape flex hoses with the spring molded in them.

Thanks,
Ed
 
just because the thermostat worked out on the bench doesn't mean it was working in the engine, I would start there, leave it out or get a new one, and 99% of all heating problems are caused by a bad radiator, ive seen thermostats stick and blow the bottom radiator hose off, no matter what the engine, if the thermo sticks closed bad things happen
 
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I mentioned previously that I installed my thermostat in the upper radiator
hose backwards. It really created pressure in the system and fortunately it
seeped out under the upper hose. Thank goodness the radiator held up and
working great now.
 
I think that the bypass holes are very important. Modern engines have bypass passages so that the coolant can circulate in the engine before the thermostat opens to prevent hot spots in the engine. The holes in the thermostat perform this function in the Model A.
 
I also have the Vintage Precision Thermostat housing that allows the thermostat to be in a cast housing instead of the upper hose. The housing has two bypass openings 180 degrees apart to allow flow when the thermostat is closed. Have some of you drilled the additional holes while using this Vintage Precision housing? How hot does it have to get to melt solder ?
 
I think Ed nailed it with poor previous repairs or poor joint due to corrosion. The steam can't melt the solder, as it couldn't have been hot enough.

I have two 1/8" holes in my thermostat and have no problems due to using a thermostat. All of my 28 problems stem from the accumulation of rust in the engine block by a previous owner using plain water.

I would have the radiator repaired by a GOOD radiator shop and be sure to recheck the torque several times during the break-in of the new engine, and now especially after the engine got hot. After my old used engine got hot last year, I found some of the head nuts very low on torque.
 
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