hpdi water pressure

[pnut]

i have an 04 250 hpdi.this winter it ran 18 to 20 lbs of pressure.now with the water temp in the 80 to 90 range today it only held 10 lbs at 4800 rpm.i have a temp gauge and it stays where it always has.cleaned and inspected poppit,disconnected water line to gauge and blew air through it.blew air through adapter in head and still no more pressure.new power head and mechanic said he changed impellor at same time.less then 30 hours on motor.am i over looking something?maybe drop unit and check impellor next.do not run in much mud so i do not think it is damaged.as usual thanks again

[iron banks]

I noticed last time out that my hpdi was not pulling as much water pressure. WOT normal is about 20 psi and this time it was 15 psi. I had no alarms and engine ran fine. I thought perhaps it was the Summer heat as well.

[JOHN202]

The heat is causing the low psi.As long as you're not getting an alarm you will be fine.HPDI stats stay wide open this time of year and your psi will go up when the water cools in a few months.

[Charlie206]

Mine was doing the same thing a couple weeks ago, just before it blew up. Now that I have it apart the water pump had nothing to do with the failure of the engine, in fact the water pump looked brand new. Carbon killed it. I assume it is the ambient heat also.

[Neilslure]

Water pressure changes with water temperature. In the winter when the water is in the 40s I have 30 psi and the needle is trying to bust out of the gauge. As the water warms up, the pressure drops. Water in the low 80s I see about 15-18 lbs. I was running in 90+ degree water and it was around 12 PSI.