The hydraulic head sleeve and rotating element is a very close fitting rotating part. The fuel filters are there to protect it. It is
so finely hand lapped to be a perfect fit and crap in the fuel wears it fast. Think 5 micron clearance,
5 microns is 0.00019685inches.
The flow benches that were used to test the mechanism are all long gone.
What was the fuel the last owners were using in Her?
Study the hydraulic head.
There has been
more than many threads here in Steel Soldiers about the HH.
post #81 in here
I believe it’s the hydraulic head. I’ve read the tolerances are so tight that if you hold the quill shaft in your fist for 10 seconds it shouldn’t even fit back into the head. Mine did with almost no hesitation and I clearly remember seeing swirl wear marks on the quill shaft. I will confirm...
www.steelsoldiers.com