Bill,

An early post on this subject indicated that your pressure measurement system has not been calibrated.  The first thing I would suggest doing, if you haven’t already, is to check the accuracy of the measurements.

Then, a way to test the effect of having an obstruction may be to be sure you have one rather than trying to be sure you don’t.  Depending on what kind of coolant lines you have, this may be as simple as clamping off the hoses and seeing how this affects the pressure change with RPM.  If you see a much larger pressure change with RPM by clamping off a line downstream of the pressure sensor, then it would be unlikely that you have a unusual obstruction somewhere in the system.

On my system which contains close to 2 gallons of coolant, an expansion volume of 4”dia x 8 long is the minimum required to avoid venting liquid coolant at temperatures up to 210 degrees.

Steve

I checked the coolant in the radiator for oil residue floating on top and found none.  The radiator was completely full with no air.  I removed a plug from each rotor and turned the engine over looking for water coming out of the plug holes…nothing.  It appears to me that the o-rings are not failed and the high coolant pressure is not coming from a leak from the combustion chambers.

I have located a borescope and I plan to inspect the inside of the radiator tank on the inlet side.  I also plan to remove the water pump and inspect as far inside the coolant passages as I can see looking for an obstruction.

Do I need to replace the gasket on the water pump when I reinstall it?  Do I need to use any sealant?  What say ye who have removed/replaced water pumps?

If the o-rings are ok and if I don’t find an obstruction, any other ideas as to the cause of the high water pressure??

What about any suggested tests???

Bill B