View Full Version : Hydraulic problems/int.3400A
James D. Owens
07-14-2007, 03:57 PM
I have a 1976? international backhoe/loader, model 3400 A,and have lost power to the hoe and bucket.Still have swing, but only 450# main pressure. Cant find anyone who is familuar with this machine. Would appreciate any help.
07-16-2007, 06:14 PM
Welcome to HEF James D. Owens! :drinkup
07-16-2007, 07:01 PM
I can not give you details, but it sounds as tho you have either lost most of the main hydraulic pump, or the main relief valve is damaged or stuck open. Of the two, I would check the main relief first. I can't remember if those models had the relief in the main control valve, or down by the pump. I don't suppose you have a service manual on it?
Actually, go to this website. There may be some better experienced help available there.
James D. Owens
07-16-2007, 08:57 PM
Hey Surfer Joe,
Thanks for the come back. I have a manual,but it dont give the location of a main relief valve. All the systems I have any knowledge of has a variable relief valve in the system before it gets to the main valve bank. This one doesnt have any. Only a relief valve at the mid-inlet port in the valve bank. I exchanged the relief valve with other ones and didnt have any difference in pressure. I have 450# on the return line going to the bucket controls, and good swing operation. I should be getting 2500# on that line.It seems that when you pull the lever for the boom,or any other function, it will surge just for a second and then nothing. Very furstrating!!
I have pulled the valve bank, and cant find anything that looks other than normal. No debrie? etc. All valves are free and smooth. I havent removed the pump as yet, since we had a good flow of oil in the return line. I guess that might be my next move.
07-16-2007, 11:29 PM
Good move on exchanging the check valves. I'd have remembered that, next week.
I'm leaning to the pump now, since you already pulled the valve bank and checked for cracks. I can see the pressure building up a bit, than dropping fast when you crack a valve open.
Can't help much more than this without being there you know.
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