When I purchased my 4500 I immediately saw that the close proximity of hydraulic lines to the exhaust manifold was a problem, so I wrapped them in foil to reflect the heat (photo 1). The power steering reservoir literally sits right above the exhaust and manifold with barely a finger's width clearance. There is a line below the manifold also with little clearance to this extreme heat source. Living in Texas I had hoped that M&M would know about designing equipment for hot climates but this almost looks like it was intentionally designed as a heat exchanger!
Fast forward 160 hours (!!!!) and last week when I suddenly had fluid coming out the top of my steering column. In a fun filled weekend I managed to remove the HSU and replace the shaft pressure seal and found that the old one was burned, brittle---toasted (photo 2; old and new seal).
I have subsequently wrapped everything in fiberglass insulation and heavy duty aluminum foil secured with SS wire (photo 3). If your tractor has this design problem and you replace the seal without addressing the root cause......be prepared to do it again.
Shame on M&M; my bad for not realizing the severity of the problem and addressing it accordingly before this.