New Radiator

[2trux]

Hey all, My 89 Ranger has been running hot so after other things I did I replaced the radiator. I put in a 3 core all aluminum radiator.
The question is ; it came with a 19 PSI cap and the original had a 13 PSI cap (which seems to be standard). Is it OK to use the 19 PSI cap or should I stick with the 13 PSI cap?

Thanks

 

[MaicoDoug]

The higher pressure is noted for holding away the bubbles from forming in the cooling fluid during use. I'm sure that standing still and not running at all, most would say to go with the lower system pressure, however when running, will the china junk stay together at the higher pressure? Might need to stick with the higher pressure to keep the ATF (transmission fluid) in the internal cooler and not failing / leaking into the water stream. Would not surprise me since it's an all too common point of failure. Differential pressure is a terrible thing.

 

[Curious Hound]

I would go with OEM spec 13psi. Just my opinion.

As noted, 19psi will hold off bubbles and boiling to a higher temperature. But, that's not how Ford designed it.

 

[2trux]

Thanks for the responses. I have a standard so no worries in AT cooling. I will stick with the 13 PSI cap and see how it does.

Dave

 

[pentode]

I would go with OEM spec 13psi. Just my opinion.

As noted, 19psi will hold off bubbles and boiling to a higher temperature. But, that's not how Ford designed it.

Plus old hoses, gaskets, seals etc... I think the boiling point for a 50-50 coolant mix at 13psi is like 260F, 19psi is around 275F. So before you need the extra pressure, you'll be having other problems, unless the 2.9 runs hotter than I imagine.

 

[mikkelstuff]

If it runs cool enough, I would stick with the 13 psi radiator cap to save the heater core.

Having replaced a couple of heater cores in my '75 Ranchero, I now run a 7 psi radiator cap along with a 3-core copper radiator. All runs cool enough even idling with A/C on and 90F outside temperatures although I had to install a much larger radiator overflow tank.