Blown Radiator?

[Tom DeWitt]

Recently one of good customers returned a radiator that was "expanded" in size. The tubes were "ballooned" and the end tanks expanded. The only way we could duplicate this damage is to crank the test pressures to 47psi. The tubes would begin to "balloon" one at a time until the whole radiator was done. It took over 90 psi to expand the end tank.
My question is "what could cause this" to happen? Why didn't the pressure cap limit the system pressure? Does it have something to do with the bypass circuit malfunction? Has anyone every seen this happen to a factory radiator?

I'm not a regular forum browser so if you have any information that will help, call me at 810-220-0181. I would also be interested in a complete schematic of the ZR1 coolant system

 

[Tom DeWitt]

Thanks!

 

[ZR1 MK]

The pressure cap has nothing to do with the problem you mention. Its a bypass malfunction, a modified bypass that wont work the stock radiator flow capability, or a thermostat that isnt installed properly. If the thermo isnt seated properly, it can cause a bypass malfunction. Did your customer have a stock style thermo? How much more does your radiator flow compared to the stock unit? Can it handle a modified bypass?

 

[Tom DeWitt]

The pressure cap has nothing to do with the problem you mention. Its a bypass malfunction, a modified bypass that wont work the stock radiator flow capability, or a thermostat that isnt installed properly. If the thermo isnt seated properly, it can cause a bypass malfunction. Did your customer have a stock style thermo? How much more does your radiator flow compared to the stock unit? Can it handle a modified bypass?

Our radiator has twice as many tubes as the factory unit, so given the same water flow it would have half the pressure drop. Or looking at it another way, it could handle twice the normal flow with the same pressure drop.

To answer your questions, I can't...and there is the problem. I have no idea (or control) what anyone is going to do to their car and when I get a blown up radiator they are ALL going to say everything was stock and working perfectly. But if this kind of failure is happening to stock GM radiators and other aftermarket aluminum radiators, then it's pretty clear it's not unique to something we are doing.

 

[90 Corvette ZR-1]

It sounds like what happened to mine. The stat was in backwards. I went through 4 rads before the damn dealer finally listened. First time I hit 7,000 the rad went boom

 

[ZR1 MK]

I have no idea (or control) what anyone is going to do to their car and when I get a blown up radiator they are ALL going to say everything was stock and working perfectly. But if this kind of failure is happening to stock GM radiators and other aftermarket aluminum radiators, then it's pretty clear it's not unique to something we are doing.

How many radiators have come back to you?
Looks like there should be a statement with the receipt and packing documents stating incorrect thermostat installation will cause a radiator failure.

 

[ßill]

About 2 months ago put in a new radiator, while I had it apart I replaced the thermostat. I put in a Stant 14068 thermostat and a DeWitt A90M radiator. After about 500 miles the radiator started leaking. I pulled it out and sent it back to DeWitts’s. Tom checked it out and said it had been overpressure. 90% of the tubes were ballooned out the end caps were also expanded. These end caps are made of .060 inch thick aluminum, that took a serious pressure excursion. I had reinstalled the stock radiator to keep the car running. After about 500 miles the same things happened to the stock radiator. Before replacing the radiator again I checked out the whole system. The only questionable part was the Stant 14068 thermostat. Evidently the pressure relief function of the thermostat was not functioning properly. After several conversations with Tom DeWitt I put the stock thermostat back in with another new A90M. The radiator in ALL of the C4’s are the same. The LT5 engine was designed with a much higher water flow than the other C4 engines. The radiator was designed for the standard engine. This means that the by-pass feature on our ZR-1’s must work or the radiator (weak point) will break! From what I’ve learned pressures inside my radiator exceeded 50psi to cause the damage that it suffered. I am attaching pictures of the stock & Stant thermostats and the housing. BTW I don’t see how the thermostat can be put in backwards. It simply will not fit.
Stock thermostat

STANT 14068

housing

Thanks for reading