I am looking at a 315 cat with around 4000 hours. Machine is clean and tight with the exception of the swing bearing. When you lift the machine with the boom you can see some movement. The gap between the upper and lower at the bearing changes by about 3/16” of an inch. You can just slightly feel the movement when digging. I am having the movement checked with the prescribed cat procedure using dial indicators to see if it is in spec. I also noticed that after I ran the machine for a while rain water was dripping out of the bearing. I know this could be a very expensive fix. I would like your thoughts on the following. How common is this? Will it get worse? Is the water drip a sign of a bad seal or plugged drain? Any other thoughts. I am trying to decide whether to bite or walk away.
1.5 mm (0.06 inch) New swing gear 3.0 mm (0.12 inch) Service Limit So 3/16 = 4.8mm. Looks like it is worn out. You can remove the access cover (6" square plate with 4 bolts) under the boom infront of the swivel and inspect the grease. I suspect it is mixed with water. if not repaired it will get worse and actually ruin the swing drive pinion. In the last 10 years we have replaced about 5 swing gears on different sizes ranging from a 315 to a 365.
First of all if the machine isn't a B or C model the 4,000 hours is absolutely unrealistic. Second item is a new bearing will have approximately 0.035 inch up and down play with the counterweight over the sprockets. Your 3/16 inch is approximately 0.190 and that is far over what is considered worn out. I usually warn people they have problems when the bearing is running 0.075 inch and if it over 0.100 I tell them they need to do replace the bearing now. Third, water running out of the bearing tells me this machine has been working in deep water as the swing pinion tub is full of water. I would suggest you consider looking somewhere else for a used excavator. Here is a short video one of the local dealers in my area has posted on a used excavator that will give you an idea of what to look for when you inspect one. mms://wm.cdn.mydeo.net/a584/o1/u/m3/e5885173fb144cd4a89209ec62f956ed.wmv Good Luck!
Basically, you need to put a dial indicator on it to know for sure. If you can see movement or feel it when operating, it's probably worn out. Just looking at it, most people won't see the allowable play in a bearing. As far as the water goes, if the drain passages under the boom cylinder foot pins are plugged this allows water to stand on the floor of the carbody. Then if there is a small crack in the boot around the rotary manifold, or the boot is not properly installed, water will leak in and come out through the bearing.
The machine is a late B and i think the hours are correct. Its at a cat dealer and belongs to cat financial. They checked it for me using specified cat procedure. It is within tolerance but just barley. It sounds like the bearing and labor would be a 12 to 14 thousand dollar fix. The rest of the machine is good shape. Not sure what to do?
I had the turntable bearing replaced this summer on my cat 307 by Milton Cat. About $8800.00 with a swivel reseal. Machine runs like a new one. I also had water coming out of the bearing after a rain storm. Was the boot that seals the swivel to the machine, it had dry rotted and cracked. Machine is 16 years old but runs great. Was worth the investment. Service manager said age, long stick with reach boom and a 30" bucket were to blame. Machine had about 5800 hrs. I have owned it since 98. An after market bearing was about $1000.00 cheaper, but I would of had to pay shipping.
If it's barely within spec at 4,000 hrs, it will very soon be barely out of spec and it's all down hill from there. That machine will need a replacement bearing some time in it's future if not now. Did you talk to the mechanic that checked the tolerances?
I didnt talk with the mechanic that checked it. The procedure is somewhat particular and the skill of the person doing the measuring could change the results. At any rate it is on the edge one side or the other. If it could be bought for the right price the repair needed might make sence?
If you know your costs up front, you're ahead of the game. Given that it's at the upper limits of the tolerance (assuming the office that's trying to get the machine off their lot has given you unbiased information), call it worn out. Get a price on replacement and use that when figuring out what the machine is worth to you.
I don't get this just barely in tolerance stuff. That bearing may be either a ball bearing with races on each side or a roller bearing. Bearings do not wear incrementally. That means that the running surfaces are not consumed as the bearing is used. I will tell you for a fact that Cat slewing bearings last much longer than 4,000 hours so in my opinion if the sales rep is telling you the hours are original he is misinformed or outright lying. The only way that bearing can have the amount of movement you describe is if the surfaces on the ball/roller and mating races have failed. I have run into numerous manufacturers that give specifications only to try to write themselves out of warranty claims. The price they gave you for the repair is in range of what I have seen other dealers do the job for. The amount of time that damaged bearing will last for you should you continue with the purchase will depend on the hours you use the machine. I'm sure you understand there is not much time left in that bearing. You can negotiate the cost of the repair into the purchase price of the machine and capitalize that into the machine cost for tax purposes. Good Luck!
4000 hours is way to early for a swing bearing to wear out. I'll bet the machine actually has 3-4 times those hours. what is the sn of the machine? I'll see if i can find any history on it.
I must admit a typo on my part in my first post. Machine is a 318 not 315. SN 3LR00407.
So if it continues wearing, can it snap the pinion shaft?
The machine appears to have the correct hours. It is a 2000 machine that was sold in 2001. March of this year is had the swing drive repaired due to the pinion lip seal leaking. This is likely related to the swing gear being worn. Either damaged from it or the cause of it. when the swing bearing wears enough the pinion can contact the carbody. This will destroy the swing drive and i have seen the pinion wear into the carbody.
So if the pinion seal was leaking that means the swing drive was most likely run low on oil? Add unknown to the list. Given problems both know and unknow does it make sence to make an offer? Any thoughts on what that would be?
The pinion seal ends up leaking because it is at the bottom of the swing machinery and all the metal flashing drifts to the bottom of the case. The oil and metal cut into the seal lip and the pinion shaft causing a groove that the seal will not seat correctly against. This seal is below the oil drain plug so the wear metals never get cleared out. Again this takes much more than 4,000 hours for this to happen. The repair involves not only a new seal but also some kind of repair for the shaft surface. I always installed a speedy sleeve on the machines I worked on. As to making an offer, it depends on the price, what you intend to use the machine for and how much money you can afford. There are also many other questions about condition that you need answered. What is the condition of the undercarriage, have you inspected the boom and stick, how much play do you have in the implement joints, what is the condition of the fluids, are there any active or logged fault codes, are there any event codes, are there any hydraulic leaks and so and so forth. Knowing the house bearing is shot and finding out that the hours are probably actual would indicate poor maintenance or rough operation. It's your call!
Asking price is 47k. The rest of the machine is good shape. Undercarrage is normal for 4k hours, hoses ok, leaks minimal if any, cylinders dry, normal play in boom stick bucket pins. Apperance is good, it aint all beat up. I would use it about 3-4 hundred hours per year. 47k is at the top of my budget. Should i be thinking about more problems to come with the swing drive? I am thinking make offer based on them doing repair. What would you offer?