Hi. I purchased a TEREX tc50 and the hydraulic level in the sight glass sits about midway between high and low when the machine is off, cold, and has everything stretched out. The second I start this machine, the oil in the sight glass disappears below low level and won’t reappear again until the next morning when I get ready to start it up again. Is this bad? I don’t know this machine yet. I checked the tank and it’s full. Yesterday I put about a quart in and the level shot up from empty to almost full in the sight glass with just a quart. I’ve never seen this before.
From my experience, hydraulics can act weird when things are cold vs. running. Do you hear any whining from the pump when it’s running? Is the oil foamy/milky when you check the tank? Any drips under the machine after sitting overnight?
everything I've read is you check the reservoir level when it's cold and everything is parked in it's... correct state for the check. Hydraulic fluid expands as it gets warm, my Dad's kubota will go from right in the middle to over the top of the gauge. Apparently it's done this since new, and other people with smaller (8k) kubota mini ex's say it's normal. My Deere raises my level by about a half inch when the rig is warm vs cold. you say yours drops the level below reading... I dunno! Does it work as expected? Oh! Thinking about it... my 50 ex, my Dad's Kubota - both of them have the reservoir above the pump. Or at least the top level of the reservoir is above the pump and all the big lines. Is the reservoir of the Terex lower on the machine compared to the engine and pump? if so, it's draining back to the tank when it sits overnight - and Terex likely designed it that way. if they didn't want that to happen, they'd have put in a check valve or put the reservoir somewhere else. I dont know man.. I've never even looked at a Terex - they just don't have them around my area. this is Cat country with a bit of Deere, Doosan and Kubota mixed in. Just no Terex - I've seen a Terex dozer... 1 in about 5 years. big, green & ugly. but probably a hell of a machine! Looks like you can get a manual from here: https://en.terex-club.com/manual_download.php?id=236 By the way, looking at the boom design on these: https://en.terex-club.com/model/terex-tc50-151 these look like nice machines! congrats on getting a well thought out rig. I wish my lower hydraulics were protected on my boom the way yours are!
The most important factor IMO is the position that the manufacturer specifies the equipment should be put in before measuring the hydraulic oil level. The illustration below shows how a similar size Cat machine should be set up. Terex may have a different requirement, I have no idea. You could try it like the illustration below and see if it makes any difference to the level when you start up.
I know on the machines with a tube for a sight glass, they will get a little air bound or maybe like a finger over a straw and not read correctly. As soon as the machine is started and there is return to the tank, the tube will immediately start filling up and it seems like it’s over full or has more fluid than you thought. On machines with a window for a sight glass, they do not seem to have this issue.