

Is the oil aerated? Sounds like you are already overfull, or you would not be purging oil. If the hoses are old enough, it is not uncommon for the inner wall of the pump supply line to seperate from the outer wall and collapse under suction. Also, a restriction in pump supply can cause the same noise. How is the upper jacket of the cyl refilled when the forks are lowered? How much difference is there between the outer cylinder tube diameter and diameter of the ram? Is there really a large enough space between them to hold any significant amount of fluid? If pump seal is sucking air you will get a similar growl. Engine is Hercules Flat head 6, we've killed a lot of forklifts in 20 years, this ole girl just keeps chuggin away. Its about 1950's Clark, was told its a HUT8 model when I purchased it 20 years ago, guys at Clark get glassy eyed when I ask for parts or technical info. Post added at 11:28 PM - Previous post was at 11:25 PM. I'm kinda tempted to just manually fill the reservoir side of the lift cylinder, then try it again:shrug. Pretty sure pump is not getting the fluid it needs, its a pretty basic system, 2 control levers on 1 block, a pump, and 2 tilt rams 1 lift ram. Finally disconnected hose from top of cylinder, no hydraulic fluid was flowing into low pressure/reservoir side of the lift ram when lowering forks.

Went to lower forks and fluid starts purging out the fill port when forks got down to about 4 feet. So I poured in 5 gallons of fluid (forks were about 5 feet up), ran the forks up a few more feet, pump still growling when hydraulics engaged. The low pressure side of the lift cylinder is also used as the reservoir for the hydraulic system, my first assumption was that it just needed fluid. Raised forks a few feet and started noticing the ram was bone dry and starting to rust. Fired it up this evening and noticed hydraulic pump was growling, there is no dipstick or sight gauge, you just fill till you can see fluid in the fill port.
#Clark forklift hydraulic cylinders manual
I've never found a manual for this old beast, and not real sure of the model#, Clark has never been able to figure it out by the serial#, so repairs are always exploratory missions. My area is sparse on hydraulic repairmen and have had some crossed eyes when asking if they would like to service this for me, hence the want/need to do it myself.Hi guys, I'm back at the shop in Texas and found a major problem on my old Clark forklift this evening. Thanks for any advice and/or tips/warning you can give me as I undertake this.
#Clark forklift hydraulic cylinders serial
Does anyone have a service/overhaul manual for this lift? The serial # is 355-0221-5671FA Is this the correct order of operations?ģ. It looks like I must disconnect the chain, take out the top snap ring, lift the mast, disconnect the lower main hydraulic hose, then raise the mast with a hoist to get the cylinder out. I have quite an array of tools but will I be needing any special tools ?Ģ. I have replaced seals on hydraulic cylinders before, but have never done a telescoping cylinder like this.

I ordered a overhaul kit from the Clark dealer, which will arrive later this week and have a few questions.ġ. She is a good runner and is serving me well but has developed quite a leak from seal on the top cylinder. I have a Clark C500-50, 4450# capacity with the telescoping lift cylinder.
