[TitaniumTT]

Originally Posted by FerociousP

wouldn't no water flow create weird hotspots in the engine?

Maybe but not much more than a stock system

Originally Posted by dudemaaan

I use a 16 psi cap. Coolant Pressure is related to the temperature of the coolant. As the coolant gets hotter it builds up more pressure. if your cap is old and weak or rated too low for your application the water will escape, this means it's not cooling the engine.

Not really, it'll still cool the engine, it will just allow the coolant to boil at a lower temp. But a 50/50 mix under 0 pressure will boil @ ~225*, add ~15lbs to it and it rises to ~270*, roughly 3*/lb so a 13 psi cap will allow boiling to occur @ ~265* If you ever get to 265*, you have other issues. The extra 2psi on the cap really doesn't do anything for better cooling except place more stress on the hoses/seals as you pointed out.

Originally Posted by dudemaaan

Usually you have a water reservoir that catches the water, and when the coolant cools it sucks it back in. If you run a cap pressure too high, this puts extra pressure on the coolant hoses and seals under overheat conditions. I prefer to run a higher then stock pressure cap, this insures the coolant is still trying to cool the engine if temps ever do get high.

True, but as I said above, that extra 2psi in the cap really isn't doing anything for us.

Originally Posted by dudemaaan

A system under normal operating temps will have the same pressure with a 16 psi cap as it will with a 13 psi cap. The only difference is when the temps go higher the 13 psi will boil over quicker.

This I will disagree with, how can a system have the same pressure if it has two different psi caps? When the pressure reaches 13psi, the 13psi cap will allow fluid to escape while the 16 psi cap will hold pressure much longer. I could run a 0 psi cap if I wanted becuase my temps never get that high. However, if they did get to ~225, my coolant WOULD boil unless I had some addition pressure in the system.

Originally Posted by dudemaaan

hope this helps. And given your somewhat complicated system I wouldn't be surprised if you have air in your system. There is a special coolant burping funnel that is supposed to work well for this. I would try to burp your system over several days to insure no air is in there.

I've seen that, never needed to use it, have a few friends that have but had no luck. A different approach would be to use an expansion tank. I swear by those now and will never build another car without one. It basically works as that burping funnell does constantly, every time you start and run the car.