BBR's 545 83GT..... it is alive

[BBR]

If necessary, I think I can increase the high side psi a bit by installing a smaller restrictor in the water neck. Right now, it's just got a hollowed out t-stat in it.

I will test my theory by squeezing off the upper hose and watching the pressure gauge.

[STINEY]

I will test my theory by squeezing off the upper hose and watching the pressure gauge.

Easy there Hoss........ don't go getting all high-techy on us!

[milner351]

Isn't system pressure determined by the cap on the radiator?

Hopefully you can go back to running a thermostat once you've determined the electric pump has adequate flow rate to keep that big mill cool.

[BBR]

The more I learn about cars, the more I realize I don't know much about cars. Cooling system pressures is a prime example of that. I always figured it was all pretty much at the same pressure, but found out there is a high pressure side and a low pressure side.

From the pump to the radiator inlet (or t-stat, whichever is a bigger restriction) is the high pressure side. The other side of the radiator to the pump is the low pressure side. The radiator cap always goes on the low side. The pressure on the high side can be well in excess of the cap's rating.

My low pressure cap is a 16, but at idle, the mechanical pump was making 20 psi on the high side. As pump speed increased, it would increase rapidly and easily blow water past a 24lb. cap in the upper hose (high pressure side). This worried me because BBF's are known for barfing core plugs and I don't need that happening.... ever.

[milner351]

AHA - thanks for the lesson - makes sense, same reason why they put springs in the lower hose, DUH, I should have realized that.

[BBR]

It ws 94 deg here today so I got to do some hot weather driving today. Water temp got to 190-ish and pretty much just stayed there. It actually went down a bit at long stop lights. Made me real happy to see that. A real test will be driving it down the highway though. High side water pressure was 18lbs when the water temp was 190, so it does not look like I am in any danger of pushing water past the upper hose cap.

[TheSilverBuick]

Temperature going down when stopped is a positive sign.

[Beagle]

It's got a big honkin fan is what I'm hearing. Good to know they are up to it, item number 793 on my "look into it" list.

[STINEY]

So does all of this mean that THESE are a bad idea?

Seems like they would put the Cap on the High side, or at least real doggone close to it?





Glad to hear you are beating down those gremlins, one by one. Good Work!

[BBR]

They might work fine if you use an expansion tank, but with a mechanical pump, it certainly will make enough pressure to bypass the cap.

I'd rather use an electric pump, have a consistent system pressure, than have coolant bypassing a cap and then having to recover it when it cools.