I purchased a 1992 Hitachi EX120-2 and am having overheating problem after about an hour of working, I believe it is hydraulic related because I have replaced everything on the water side. I don't have any engine manuals but I seen on here that someone mentioned the hydraulics might be causing the engine to heat up. any help please. I am not a mechanic but can usually put something back I take apart. Thanks Dave
Search results for query: Hitachi EX120-2 dhtauto.com This site has manuals, how you pay for them IDK. SOme are free, some not. Joe H
I’m having similar issues, but while running my breaker. 1) I don’t think that the outfit that set my hammer up has the flow correctly 2) Breakers just dump fluid back to tank, so I might need larger return line. 3) Hammer itself has bad O-rings in valve body letting too much fluid through. Friction is heat. I have a copy of Manuals I can sent over if you DM me with your email
Are all the foam seals around and between the coolers all still in place? Worked with an old school Hitachi guy and I remember him telling me that the missing foam was a very common source of overheating. That and running with missing panels/open doors.
The doors open cause heat? I’ve seen more than a few 120/200 with holes drilled in the doors
Apparently it messes with the air flow through the coolers. I can't say for certain, been years since I've seen an EX Hitachi. Even the original Zaxis machines are hard to come by.
He is talking about "ENGINE HOOD" not the "DOOR". As for the door, it can make holes or even open while the machine is working.
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I see a lot about hydraulic oil getting hot, what is a normal temp at the oil cooler using a temp gun?
Your breaker manufacturer will have a max return pressure spec And supply spec. I know for certain the Indeco breaker needs less than 105 psi. Measuring at the breaker. An Okada breaker can run up to 250 psi. I have set up more than 50 breakers on excavators Just using a good flow meter. Without the attachment. Sometimes the return side needs to be one size bigger the the supply side to get the return pressure down.
In my experience in most cases a #12 is adequate for a return line unless you're running a big excavator, something in the mid 20 ton range and up. Obviously a bigger line and 45° fittings vs 90° fittings will be better. What really gets the back pressure up is not switching the return so it flows straight back to tank. Running the breaker in 2 way flow mode often adds a couple hundred PSI when the return flow is forced back through the main control valve spool.