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1975 518 cat skidder

Started by Caseybow123, April 22, 2017, 05:18:59 PM

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Caseybow123

Can anyone give me advice on a 518 caterpillar skidder? I just picked one up because the price was right. Any major issues with these machines to watch for? Everything seems to be good that I can see other than the gearmatic winch (not surprised).

coxy

they don't have the power the newer ones have after 82 I have an 81 its gutless come paired to the newer ones :)  always check your tranny after 4-5h of use and let it idle for at least 10min( it will slip being only a gal low on oil )the newer 518s run motor oil in the trannys the book for mine  calls for 30w tdto tranny and drive train oil there is thinner oil for the winter but I run 30w year round takes about an extra 10 min to worm up in the cold they hold 10 gal and its not cheap so I change it every other year but change the tranny filter in the spring and fall  make shur you grease the fitting under the drive shaft by the winch there is a big bearing there for the back pivit there is also 2 more fittings by the rear drive shaft on the bottom where it turns one on the left the other is on the right the one on the left standing behind the skidder is hard to see the drive shaft yoke has to be just right or you cant get in there  one other thing parts are not cheap I always get the cat classic parts they are after market but less than half of a true cat part and work just as good   good luck with it

mills

I can't complain. Mine's an "86" with a grapple, and haven't had any major issues with it other than normal wear and tear. Sucker will pull a load.
Have had some problems with the winch jumping out of gear when pulling in a load. Haven't figure it out yet, but it's caused me to shear a few pins in the shifter.
Went at it a piece at a time, but had to totally rebuild the brake system when I first got it. Haven't had any problems with the drive line.
It's worked well for me.  8)

Caseybow123

One thing that is evident to me after running the tj or jd, is that the 518 doesn't produce much rpm. Is this normal because I would think the 3304 turbo would be more aggressive than it is. I haven't tested yet but I  would say it maxs out about 2000 rpm.

coxy

they have more lugging power  the cat will pull more at a lower rpm than a Detroit   the newer 3304s have way more power than the older ones with the combustion chambered injectors  pulling up hill with 6-7 trees it wont stop but a turtle will pass it  :D one more thing an old cat guy told me not to turn it up much cause the pump in the tranny wont take the pressure

Caseybow123

I just discovered that I have no brakes. When I shut the machine down I can hear air escaping for about 10 minutes. It is coming from under the instrument panel where the brake pedal is located.

Caseybow123

Leaking out of the end of the valve group beside a c- clip above the pedal. Anyone have issues like that?

coxy

 you have no brakes at all  :o   you need brakes mine was a pile of crap with out them and if your skidding down hill with out brakes on them its a death wish they will run away with them self till you get real use to it  mine if skidding down step hills ill hold mine to the floor to help hold it back    but don't try it till your use to it its not a fun ride the hill I'm coming down now is so step ill loose half my oil pressure its only about 500ft long but cuts a half mile off my skid   does your parking brake work at all  try hitting the b pedal fast and hard a few times the rubber maybe dryed out I had trouble with the rubber pancake by the master cylinder they would work for about 30sec then fade away but I could hit them then let off and hit them again but that gets old so for 20 bucks I got a new brake can same as the one on a big truck for the front brakes

Caseybow123

Absolutely no brakes at all and the parking brake cannot be moved. Brake pedal goes to the floor and all you here is air escaping after you shut off machine. I fortunately have very little hills where I live in Canada.

mills

Never had a leak under the dash, but like I said in my earlier post, I had to work my way through most of the brake system in the first couple of years I had it. And I totally agree with Coxy, they might lumber their way up a hill, but then do a free fall going back down...which is usually where I found out that I didn't have brakes.  smiley_sweat_drop
Just about burnt the dang thing up the first time I drove it from one job to the next. The boys I bought it from seemed to do a good job staying on top of the basic maintenance, but didn't believe in routine bathing. I knew he needed a bath, but being behind, I unloaded it off the truck and put her to work. Thought I would catch it on the first trip past the house. Well about four miles into a five mile move the parking brake must have lost air and bled off. A little oil mixed in with sticks and leaves burns pretty good.  bon_fire
Thank the Good Lord, but they had a full fire extinguisher mounted in the cab. Yep, maintaining brakes can be important.  smiley_thumbsup

Caseybow123

I am hoping that it is just a leaking air out a seal, plunger, boot etc in the valve group by the brake pedal. I won't know until I dive into it. I am new to the cat air brake system so it may be a slow learning curve.

Spartan

do you have a pressure gauge for the air tank?
Yeah that valve under the dash is what supplies the air cans under your feet.
You should have one for the front brakes and one for mid ship disc.
You can also run plumbing under the dash for an air line to air up tires or a blow nozzle too which is pretty handy.  maybe its already there.

When you get them going, don't leave your e brake on and start skidding or your front brakes can catch fire.
make sure you bleed your air tank once in a while, (our purge is tube at front right bottom of engine) if you start getting oil in there, means your pump is blowing oil into it.  They make a rebuild kit for the air pumps as well, that you can just replace the upper cylinder parts.

another good thing to know on the brakes is that because they are air powered, if your machine dies, you will have only a limited amount of braking before the air goes bye bye.  Then, no brakes. 

Caseybow123

Thanks Spartan, that sounds like a really good place to start. If I get it figured out I will post what was wrong.

coxy

Quote from: Spartan on April 23, 2017, 10:29:11 PM
do you have a pressure gauge for the air tank?
Yeah that valve under the dash is what supplies the air cans under your feet.
You should have one for the front brakes and one for mid ship disc.
You can also run plumbing under the dash for an air line to air up tires or a blow nozzle too which is pretty handy.  maybe its already there.

When you get them going, don't leave your e brake on and start skidding or your front brakes can catch fire.
make sure you bleed your air tank once in a while, (our purge is tube at front right bottom of engine) if you start getting oil in there, means your pump is blowing oil into it.  They make a rebuild kit for the air pumps as well, that you can just replace the upper cylinder parts.

another good thing to know on the brakes is that because they are air powered, if your machine dies, you will have only a limited amount of braking before the air goes bye bye.  Then, no brakes.
if your parking/maxi brake is adjusted and working right and you loose air you come to a sudden stop just like a big truck  I also run air brake antifreeze in mine in the winter I take the main line off that goes in the tank and pour it in there and work the parking/maxi brake button in and out and push the brake pedal a few times to work it through the system

Caseybow123

Hey guys still a little confused on these brakes. Do they operate like a tractor/trailer system as you need air to release the brakes? Spartan says when it loses air then you lose brakes, however coxy said when you lose air the brakes lock up. I would think with no air the skidder would not move, but unsure.

Spartan

well our parking brake is removed, so it will lose air after the engine is off and bleed the system out.  So it will move without air (the machine)

You'll have to wait for coxy to chime in on what he was talking about.  My guess is the parking brake acts like a maxi.  Wheather thats only when its engaged, or all the time I don't know.
I started running our cat after the park brake was removed, so all work I have done on the system has been without that.

I stand corrected on my statement of the machine will lose brakes if it dies (ours does), and we'll have to see what he means.

Did you find where the air is leaking out of yet?  There should be a supply hose that comes in under the dash, then drops down under the floor boards.  If there's a leak under there you should be able to run your hand over it and feel where it is.

coxy

 yes they are like a tractor trailer if your parking/maxi brake is working right    you have 2 brakes a foot brake and a parking/maxi brake the maxi/parking brake knob or button is on your right side by the winch lever pull up to lock parking/maxi push down to release you can not move the shift lever if the parking/maxi button is on don't matter if it works or not but you must have enough air to release the button other wise it will or should pop back up if there is not enough air built up  if your driving and you pull the parking/maxi button up it will automaticly go in  neutral and stop if the parking/maxi brake is working right    just like a big truck with air brakes if you pull the maxi/parking brake you should come to a sudden stop if you cant build air your parking/maxi brake will not release and you wont be able to get it in gear( only on the skidder) the big trucks will still go in to gear   if you take off the little plate on the belly pan/skid plate under the skidder it will be the last plate where it turns in the middle if you look up in there you will see the rotor and there will be a bunch of plates with pins that is your parking/maxi brake on the vary top is your foot brake they use the same rotor but the foot brake pads a 5x bigger than the parking/maxi brake pads

coxy

Spartan what year is your cat  the ones with the diamond shaped  roll cage 81 aqnd older had a different style parking/maxi brake than the ones with the straight roll cage

Spartan


Caseybow123

Spartan, in response to your question if I have isolated the leak, my answer is yes. I can feel air escaping out of the very tip of the valve body or valve group  (as the book says) under the dash directly above the brake pedal. It will bleed off air for app. 10 minutes after engine shut down,however as a newbie to cats I have no idea what it all involves to replace or rebuild. With the caterpillar name and that yellow paint I know it won't be cheap. I am just praying it is one fix and not the beginning of a string of issues that can break the wallet.This is probably familiar to you as well if you own a cat, lol.

coxy

always ask for cat classic parts first they are cat after market and less than half of oem and just as good imop I put a new muffler on mine      cat oem was 360 bucks :o  cat classic 96 bucks

Caseybow123

Thank you very much Coxy, that will definitely ease the pain some when repairs start.

JustinW_NZ

MY 528 has the same brake problem.
I bet its the same - mine was the tredel? valve - mine was leaking, then really let go, so you hear air escaping and the brakes wont come off.

Its directly behind the brake pedal on the engine side of firewall with a few line going in/out of it.

The outlet port probably has air coming out all the time use a hose to your air to find it.

Cheers
Justin
Gear I run;
Woodmizer LT40 Super, Treefarmer C4D, 10ton wheel loader.

Caseybow123

Yours is a different location Justin. Mine is leaking all the time too but I can still use the machine, I just have no brakes. Your leak you say is on the engine side, mine is not.(Under instrument panel in operator station)

JustinW_NZ

Yes, im not sure on the models where they are but i bet yours is leaking on the other side of the valve, because mine is just venting i cant get the brakes off :(

Quote from: Caseybow123 on May 11, 2017, 10:29:01 AM
Yours is a different location Justin. Mine is leaking all the time too but I can still use the machine, I just have no brakes. Your leak you say is on the engine side, mine is not.(Under instrument panel in operator station)
Gear I run;
Woodmizer LT40 Super, Treefarmer C4D, 10ton wheel loader.

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