Thanks for the feedback everyone. Interesting points. I don't believe my pump cavitates during the winter. I do get some good noise on cold startup but I think that is the starter not retracting the gear quite quick enough. But now that I think about it I'm not too sure....
Interesting point about the fluid not getting any colder during start with or without the extra cooler. As long as the heat from both the engine and the pump/gearbox would sufficiently heat the fluid to keep it above that cavitation point during normal driving. I suspect, like mentioned above, that using a good quality synthetic ATF would help with this. (Valvoline Dex6
had the 2nd lowest CST rating at cooler temps than other ATF's I looked at as well as regular power steering fluid. Mobile1 Syn ATF
had the lowest with a viscosity at -40c of about 10,000 cP. The M1 was almost twice the cost though...)
I don't really wheel hard enough or with big enough tires to have experienced cavitation before. I admit the thought of installing the new cooler is more a matter of convenience since the rest of the system is disconnected, and I had kinda viewed it as an upgrade (just not sure if its an appropriate upgrade for how I use the truck.
) But if it kept the seals alive in the box and pump a while longer, it might be worth it.
I suppose I could always give it a try assuming I can get the paperclip out in one piece, and hold onto it and could always re-install if necessary.
'97 lx450, 170k, factory lockers, ome 850/863, 285's, 4 working doors(1 more than the old fj55 )
'74 project pig (sold