Cat don't manufacture dessicant-type filters. However I personally think you're going off on a tangent here and trying to over-think things. The tank has had condensation in it, true. However replacing the tank cap and all the seals for the various covers on the tank should fix that. Once the tank is "sealed" for want of a better word the air in it is never going to change and no moisture will be able to get in or out. At that point do a complete oil drain and replace with new oil and you should be good to go.
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Nige,
Thanks yet again. I'm definitely prone to overthinking, sometime in tandem with 'underacting' - especially when the weather's bad and the alternative to actually
doing anything is to keep on googlin.'
But I have to ask about the tank-breathing dynamics again...going into this, I'd for some simplistic reason thought the "radiator-style" pressure cap was effectively a check-valve that would keep my tank from exploding by providing a means to *vent* pressure - and only to vent. But mustn't it also provide a means for the tank to take IN air when needed, as well, so that, after a long hot day of machine use with the oil heated up and air burping out the cap regularly, when the temperature subsequently dips into freezing territory that night (OK, that never happens here, but you take my meaning), the tank doesn't buckle/collapse? (My model on this is how radiator caps work - expelling coolant when hot to the overflow tank, then taking it back in via a second spring-check). So assuming that's also the case with my cap, the occasional slug of air that the tank might have to gulp in (through that dangling hose) might indeed be very wet. So wouldn't it be true that even a factory-fresh pressure/vacuum cap, I will still be gulping in occasional wet lung-fulls of air? Maybe my assumption about the two-way valving on the cap is flawed, but it seems intuitively necessary that it work that way - else how does the tank ever take in air?
...IMHO the fact that you are using ATF as a hydraulic fluid is not helping things. ATF is too light for your climatic conditions (it's a bit less than 10 weight, you should be using something closer to 30 weight or ISO 68 viscosity) which will result in the hydraulic oil getting far hotter than it should due to the churning effect of the lighter oil. Also ATF has a tendency to absorb moisture far more than a hydraulic oil which is the last thing you need bearing in mind your current tank issues.
You also mentioned fuel tank water issues in this and other machines that you have in the damp climate of your location. The solution to this is relatively-speaking simple: -
1. Always fill fuel tanks right to the top at the end of every working day to reduce condensation.
2. If 1 is not possible install a full-flow dessicant breather in the fuel tank vent.
3. Drain any accumulated water from fuel tanks daily as opposed to weekly that the manual recommends.
4. If you have any machines that are not equipped with a combined primary fuel filter and water separator that permits draining water from the bowl below the primary filter then you should install them. The water separators should also be drained daily.
re: replacing fluid - is just "ISO68" an adequate specification? Any concerns about brands? Any hot tips on sources?
re: (4) - definitely... in the wake of my recent IP rebuild for this machine, I bought a bunch of new twin-filter "CAV-style" fuel-filter heads, apparently well known to Ford tractor users. For some reason, they came with no tech data, and seller hasn't been able to provide any yet, either, but indicated that they'd just 'drop in' where the old one had been, so not a lot of thought would normally be needed. One side has a glass bowl, the other an aluminum bowl. I'd assumed when I ordered them that the design of these was to filter the fuel in
series, but they're actually made to work in parallel, which seems less than optimal, esp since there's only one glass bowl & drain. There are four ports with arrows in/out, numbered 1-4, but it's clear from looking into the drillings that the "clean" fuel is common to one long passage, and similarly the 'dirty' fuel is commingled by design. I actually went to the trouble to modify one such that it works in series, with the glass bowl side being the primary filtration, and it's ready for use on the CAT now. Others will go on other machines/truck/whatever soon. Do you happen to know about the parallel/series-flow concern there? Maybe these are for some reason intended to be essentially one large filter, not two stages?
I much appreciate all the assistance & details on other issues not mentioned in my reply...working on implementing.
Thanks again -
Dave