Anyone else have the boom and rotate go sluggish on a 2012 Altec AA55 around 6 a.m. today at 28°F, even after high idle and cycling the outriggers? Thinking about switching to ISO 32 and adding a tank heater, but I don’t want to risk cavitation — what’s working for you folks running bucket trucks and digger derricks in the cold?
Had the same on a 2011 AA55 around 6 a.m. at about 28°F; instead of going to “ISO 32” I kept ISO 46 and stuck a 500W adhesive pad heater on the reservoir with a timer (on 4:30–6:00) and the boom/rotate stopped lagging with no cavitation noise. If you don’t have shore power, a magnetic pan heater works but it’s slower. Do you have 120V at the yard to preheat the tank?
On my ’13 AA55, pulling the tank suction strainer and cleaning the sludge cured the “sluggish” boom at 25–30°F; it was starving the pump even at high idle. If the strainer’s clean, a high‑VI AW like Mobil DTE 10 Excel 46 has flowed better for me in cold without dropping all the way to 32. Have you ever serviced that strainer?
And “6 a.m. at 28°F” — . I’d skip ISO 32 and run a high‑VI 46 instead (Mobil DTE 10 Excel 46: https://www.mobil.com/en/industrial/lubricants/products/mobil-dte-10-excel-series) with a 3/4 NPT immersion heater on a timer, then warm it 2–3 minutes by cracking the tool circuit to tank; if it’s still lazy, make sure the suction hose isn’t collapsing even if the strainer’s clean, @james45. Do you have a free‑return/tool bypass you can use for that warm‑up?
Before swapping to ‘ISO 32’, check the suction side: a cold‑soft suction hose can oval out and aerate, which feels just like sluggish boom/rotate at that pre‑dawn 28°. Feel for collapse, watch the sight glass for bubbles, and swap to a wire‑reinforced suction hose plus a fresh tank breather if you see it — beats chasing ‘cavitation’. You getting any faint pump whine at high idle, @OP?
Quick test: does it improve if you crack the fill cap? A plugged or iced tank breather will pull vacuum and make the pump lazy, and if boom and rotate both lag I’d also check the tiny pilot/LS screen on the control manifold. A small magnetic heater on that valve block helps more than just warming the tank, @AltecTech.
I’d watch the “return filter indicator” at cold start — if it’s in bypass or pegged, the element’s choking flow like a milkshake through a coffee straw; swap to a winter‑rated element and cut the old one open. Also do a quick “jar test” for water (haze/ice at fridge temps), since moisture will make it lazy regardless of oil grade. Do you have a case‑drain filter on that pump, and when was it last changed?
I’d put a hand on the cooler lines at cold start — if they’re moving oil right away, the thermal bypass is likely stuck open and you’re pushing syrup through the cooler, which makes boom/rotate lazy; pull and clean or swap that bypass cartridge. Thinner oil might help, but it won’t fix a stuck bypass. @harris66, does that AA55 have the warm‑up/bypass block on the tank outlet?