HI! New to this forum. I have a new-to-me mid 1980's Caterpillar 215 Excavator that was rode hard and put away wet. She was pretty banged up when I got her, and none of the gauges work. But the engine fires right up, and sounds strong. The hydraulics however, have problems. And I've got some beginner questions I could really use some help with: When I bought the machine last fall, the previous owner demonstrated it's functionality: the machine ran smoothly as he put it through it's paces. But after the machine was delivered to my site, the arm and bucket motion was anything but smooth. I attributed it to operator error (i.e., me). I didn't use it too much after that before it got cold... Now it's spring, and I'm getting back out there. I greased all the fittings on the boom, dipper stick, and bucket. I noticed I needed to add hydraulic fluid to the tank last week, and when I cracked the cap, I heard air whistling in for several seconds - maybe as long as ten seconds or so. I hadn't used it for about a week before that happened. I was still low on fluid, so I came back with more a few days later, and the same whistling when I removed the cap. I also noticed when I first start it and lift the boom, the bucket swings free like a pendulum for several seconds. And the controls are not smooth at all - a lot of hesitation, herking, jerking, and banging, no matter how slowly I move the controls. The machine doesn't feel like it wants to rotate either. I'm thinking I'm getting air in the system, perhaps because there's a vacuum in the hydraulic reservoir? I think the hydraulic tank should have a breather, but I (a) can't find it, and (b) don't know what I'm looking for. Are there bleeder valves somewhere I need to look for? I'd like to find a manual for it, but I imagine I need the serial number to get the right book. Any idea where the serial number might be hiding? Most of the label plates are well worn, and barely legible, and I don't recall seeing one with a serial number. I'm hoping Caterpillar has copies of manuals for these old machines. If not, does anyone have an idea where I can find them? Thanks for your help!
Was air going into or coming out when you loosened the cap? Very common to have some pressure in the hyd. reservoir maybe 5 PSI or so. It helps prevent cavitation. If my backhoe sits for awhile the bucket will flop around when I first lift it off the ground. I think it could be due to internal cylinder seals leaking a little bit. Once I cycle the bucket open and closed it's fine. First thing to do is make sure the reservoir is filled to the proper level and also make sure there's no leaks especially on the suction side. It takes a bunch of seat time to get smooth with an excavator or backhoe. If you can operate 2 functions at the same time makes it smoother to operate. I'm not sure but it might have a swing brake for transporting it. Shouldn't be hard to get a manual but you need the serial number. I'm not sure where it's located. One of the Cat experts would likely know. If not they might be able to figure it out from the engine serial number assuming it's the original engine. Maybe the previous owner could provide some info on it and also tips on operating it? If it worked smooth for him it doesn't seem like there would be too much wrong.
Look on the upper (revolving) frame right around the point where the boom cylinder are pinned to the frame. The Serial Number plate should be somewhere in that area. Don't take the illustration below as gospel. The plate #1 is shown as being on the LH side of the boom base but could just as easily be on the RH side.
Thanks Welder Dave! Ok - I found the serial number 57Y00756 on the door. And you were correct - there was some pressure in the tank, not a vacuum like I suspected. I tied a plastic bag from a loaf of bread over the filler neck with a rubber band and cracked the cap. The plastic bag promptly filled up, but didn't blow off, so it wasn't that much pressure. I think I found the breather (or perhaps this is a relief valve?) on the top of the tank, but it's on the far side of the cover, so it wasn't visible it first. I'm surprised it held that much pressure since I last used it a week ago - perhaps that's a good sign? I checked the hoses around the hydraulic pumps - most are damp with oil, and there definitely been some weeping from a couple fittings, but no gross leakage. It ran nice and smooth for several minutes today, but after maybe 15 minutes, it was back to being jerky, and it got worse the longer I used it, so much so that after an hour I called it a day, not wanting to break anything. I checked all around - no gross leakage, and the hydraulic lines barely felt warm, so I'm pretty sure the hydraulics are not overheating. Would a leak on the suction side of the hydraulic pumps cause that? If so, any suggestions how to find such a leak?
Thanks Nige. I'll look around the boom base next time I'm out there and see if there's a number there, and if it's the same as what's posted on the door or not.
I seem to remember those tanks need to be sealed. I think some put boost into tank. Nige might be able to find something. Of course that was a long time ago I might be remembering wrong
Was that on a plate or written in permanent marker.? The Serial Number plate should be here........... If it is on a plate please post a photo. Your excavator dates from 1981 BTW.
On to the subject of manuals. The basic Operation & Maintenance Manual comes in two parts. Cat Publication SEBU5817 covers operation, SEBU5818 covers basic maintenance and servicing. The only ones I see online are on eBay at $70 each which is more than double the new price. These two manuals can be downloaded from Cat for $30 each The Parts Manual covering all 57Y-prefix machines is HEBP1285. Here's one on eBay A Service Manual covering all aspects of repair and diagnostics, troubleshooting, etc, is SENR2165. Again a link to one on eBay
You are referring to #22 I imagine.? That is what's known as a breaker relief valve. If the pressure in the tank rises too high it will open and relieve the pressure. If the oil temperature goes down far enough to create a vacuum above the oil the valve will open to allow air into the top of the tank. Under vacuum conditions it relieves at 0.1 ± 0.1 psi, or around 3" of water. Under pressure it relieves at 20 ± 3 psi. The idea of always having a positive pressure in the tank when the machine is operating helps to push the hydraulic oil into the implement pump suction side and should in theory prevent cavitation. T
It's odd it would work fine for 15 minutes but get jerky once the oil warms up. I'm not sure what type of hydraulic system it has but wonder if a charge pump could be getting weak or there is an air leak causing the jerkiness. It is good that the reservoir holds pressure after sitting though.
Wow! Thanks Nige - I'll definitely be looking to order those manuals this weekend. The serial number on the plate(s) on the door was engraved. I'm trying to attach a picture - hopefully it works. The plate on the left is engraved 57Y00756, and the one on the right is 57Y 756. I think the machine engraved "198_" and the hand scribed 1 is the manufacturing date, which matches what you said. I think someone got cute and tried to modify the date to read either 1984 or 1987... The relief valve on this machine looks almost like your #22. On my machine, I don't see the part #2 in your illustration that #22 is attached to. On this one, #22 is more like a straight pipe attached to the top of the tank with a mechanism of some sort recessed inside of it.
Thanks all. So, you were correct Nige, there's a small plate on the base of the boom where you indicated it should be. It's faintly engraved, and pretty scratched up. I couldn't get a decent picture because of the glare. I think it ended with "... 56", but I couldn't make out the rest of it. My guess is it's the same number as the plates on the door. Speaking of the boom, I inadvertently left a big piece of cardboard out under the machine a few days ago, and I noticed today a sizeable amount of oil had dripped on it. As luck would have it, the oil slick was right below one of the hydraulic cylinders for the boom, about where the wiper seal would be. And I noticed the outside of the cylinder was also pretty slick with oil. The other boom hydraulic cylinder was also dripping from the same spot. So, it looks like I need to replace the seals on both of those hydraulic cylinders... I'm guessing this the bad seals explain a lot of the performance and control issues I was experiencing.
I thought the plates inside the cab were not standard, but at least they have the information. The selling dealer must have installed them. Fun fact - Bergerat Monnoyeur have been a Cat dealer for almost 100 years. Interesting that your machine was built in Belgium and originally sold to a customer in France.