broken 312

[cheifrider]

hi guys , im new to this forum and introduced myself a few days back , at that time i also tried to get some advice but it didnt work out to good in the "intro"section of the forum.anyhow , my name is tom and i live in the adirondack mountains of ny , i just bought 130 acres here that will someday be a fine sugarbush . in order to do that i bought myself a 1994 cat 312 ,well last winter i was moving it and all the sudden it felt like i was up against an object (i was in the complete open)i backed up a tad and went forward ,thats when i heard this no so good "bang" noise , i shut the machine down and observed hyd fluid leaking on the ground from one of the final drives .it was nasty out so i left the rig be until spring.on last observation the hyd fluid was out of the sight glass.
here are my questions:
1. where could i find an excerpt for the final drive part of the shop manual?
2. im fairly mechanically inclined , can i do this repar?
3. if i take off the cover on the INSIDE of the final drive am i opening a can of worms?
thanks in advance for any help you can send my way , tom

 

[cheifrider]

well i was hoping someone could give me a hand , just thought i would refresh this post and see what happens ,regards,tom:beatsme

 

[Per Eriksson]

There are 2 types of drive motors and finaldrives on these, do you have a serial number?

By cover do you mean the sheetmetal that is bolted with 4 bolts, if so go ahead and remove that, nothing but some old dirt will come out.

 

[cheifrider]

There are 2 types of drive motors and finaldrives on these, do you have a serial number?

By cover do you mean the sheetmetal that is bolted with 4 bolts, if so go ahead and remove that, nothing but some old dirt will come out.

hi per ,thanks for the reply .
the serial number of the machine is 6blo166x, also the covers on the inside of the final drives have 6 bolts. thanx,tom

 

[willie59]

Hi cheifrider, that serial number is most likely 6BL zero. In most cases, the use of an "o" in a SN is avoided as it's difficult to distinguish a zero from an o using stamped numbers, so it's typically a zero.

If your machine is not a gray market machine, and you're the owner of the machine, you should be able to set up a user account at the website of your local Cat dealer and view the parts pages for your machine online.

 

[Cmark]

OK. The usual Caterpillar insiders are being quiet on this one, so I'll be the one who has to break the bad news.

It looks like this particular final drive is prone to failure. Cat knows about it and appears to want nothing to do with it.

To quote a couple of paragraphs from SIS;


"Serviceability Of 312 Travel Groups 125 9728
SMCS - 4050

EXCAVATORS
312 (6BL926-Up)
Problem:
The travel group 125 9728 cannot be completely dismantled at Dealer's shop. Some of the parts require specific tooling and procedures that can be applied only by the manufacturer.

Solution:
It has been decided to not service all components.

For any information on this subject, please contact Caterpillar Stex Product Support.

Caterpillar doesn't recommend to remove the third stage of the gearing which requires to destroy gear shafts 128 1834 and shaft nut 128 1833. If a problem occurs at this level, at duo cone seal level or at ball bearing level, we recommend to not disassemble the travel group and to contact immediately Caterpillar Stex product Support to get instructions"

and;

"The motor housing acting as a planetary carrier may suffer from a fatigue failure on some machines because of the casting's metallurgical structure.
In case of failure, the four posts of the motor housing will brake, leading to a total destruction of the drive group."


I'm afraid that if you want to have a go at repairing it, you're on your own as far as Cat's concerned. Basically, Cat's recommendation is to install a new 142-6825 final drive group.

But you won't be on your own as far as the forum's concerned. Post some pics of what you find and you'll receive the best advice that money can't buy.

 

[cheifrider]

cmark, many thanks for the good news!that just made a perfect day more perfect !i will keep you posted on my progress .im sure there are people in this forum that deal used parts?regards,tom

 

[cheifrider]

i was wondering ......in your last post it says sn;6bl926, and up.my number is 6bl0166x , wouldnt that make my machine way before this service bulletin was published ........just thinkin out loud , tom
ps, i took off that inner cover on the final drive all i found was a lot of dirt everything LOOKED ok .

 

[Cmark]

Cat serial numbers are made up of a prefix, in our case 6BL - which tells us it's a 312, and a suffix, a five digit number which tells us the order off the production line.

When Cat people talk serial numbers to each other, it's common to drop off the leading zeroes of the five digit number, so your machine becomes 6BL166x (one thousand-six-hundered-and-sixty-something). The service letter applies to 6BL926 (nine-hundred-and-twenty-six) and up, so your machine falls inside this range.

Good luck. Post a few photos to keep everyone interested in this thread.


Edit; when you say 166x, you're hiding the last digit, right?

 

[cheifrider]

cmark, yes the x is a number , thanks for the sn info , im waiting on cat to get me set up with an acct so i can utilize their online services regards ,tom

 

[cheifrider]

update fellas .....i got the final drive and hyd motor out of the machine .i never knew it could be so much fun!i have a bud who wrenches on these things ,tell me that because i found metal chunks in the hyd drive pump , that i should probably just go look for a used pump/ final drive , or a reman one .(just to update , i have a1997 cat 312 sn 6 bl 0166x)if the drive assy i have is toast , where would be a good place (other than cat) to go looking for used or reman parts .( i live in upstate ny)and lastly what might the gurus in here think about rebuilding this pump assy .should i even take it apart? my friend says not to because whoever i do business with will more than likey want my old parts for a core , and if its been apart it may sour the deal .your thoughts on this are appreciated . tom c.

 

[Jam]

Cat serial numbers are made up of a prefix, in our case 6BL - which tells us it's a 312, and a suffix, a five digit number which tells us the order off the production line.

When Cat people talk serial numbers to each other, it's common to drop off the leading zeroes of the five digit number, so your machine becomes 6BL166x (one thousand-six-hundered-and-sixty-something). The service letter applies to 6BL926 (nine-hundred-and-twenty-six) and up, so your machine falls inside this range.

Good luck. Post a few photos to keep everyone interested in this thread.


Edit; when you say 166x, you're hiding the last digit, right?

Does this final drive problem affect all machines until the c series was introduced or was it sorted out?

 

[JGS Parts]

mate feel free to shot me thought an email i can quote you on a price for the gearing and things you need if you have the part number iam not based in the US but we get some super cheap CAT parts here and i have seen the same thing as your machine happen a heap of times , I found a few of the Hitachi EX120-1 we had used to do that also. mate if its just being used on a farm and by the sounds of things its not an urgent repair you might want to even look at a used one but in saying that if this is a common problem you might want to becareful you might be buying another bomb!

 

[JGS Parts]

sorry mate email was james@jgsparts.com

 

[cheifrider]

james, i've been thinking the same thing about "buying another bomb" .....thanks for the insite . to up date this soap opera a little more i've found ,what i believe , to be a "production date " on the id tags on each motor . keep in mind the machine is a '97 but BOTH motors have a date of '99 (one is sept , one is nov.)did they recall this thing once ?as cmark commented earlier cat basically washed their hands of this repair (which i think really sucks and will be considered in my next purchase ).........ummmm
while i'm venting , does anyone else always seem to have that EXTRA SPECIAL machine which needs EXTRA SPECIAL PARTS , or the parts are made out of un- obtanium ?
ok i'm done with that , .....b-4 i get started on politics!. my next querry is....the actual final drive on this rig may be fine ?the pump motor seems to be the problem here , as thats where i found "particals". i'm just guessin' as i cant seem to find a service manual anywhere .even a parts book with kersploded images would help me.thanks again for any help fellas , tom

 

[freedom digger]

Chiefrider,
I have a service and parts manual for a 2000, cat312 if you it would help I could try to look up and scan the pages you may need I think they are mostly the same especially if your drives are 1999.

 

[cheifrider]

that would be great! i sent you a pm. thanks ! tom

 

[stumpjumper83]

Chief, thanks for the post. How many hrs are on your machine? I was actually considering getting a 312b but witht he cost of finals and the admitance of cat to problems, I think I'll pass on the cat, maybe I'll find a deere which is what i really want anyhow.

Parts wise if your in upstate ny, give HR equipment a call, they handle alot of remaned finals and such.

 

[cheifrider]

i have 2660 hrs on the machine , it kinda pisses me off to know(or assume ) that the finals have allready been replaced once, only to take a dump again.when does it stop?i'm seriously considering gettin this thing fixed and unloading it .just an aside here; i found a brand new final assy , $14000, go figure!i'll try hr equipment , thank for the lead , tom

 

[CRAFT]

Personaly as an Owner/Operator of a 312A Model with 5000hrs .... this is the first time i've ever heard of final drive motor issues ...... granted there maybe a batch of bad ones out there, but to outright blast every 312 ever made is BS .....

Cheif ..... with 2660 hrs, there's got to be more to why it's had 2 failures .... maybe it was a back yard repair and the hyd's was not flushed properly, contaminating the second causing a premature failure ..... how many hrs did the original go, was it serviced regularly ect. ..... either way ..... sorry it doesn't sound right .... not with the apparent hrs this unit has and knowing of the same yr machines running around with over 14,000 hrs on them with original drives ...... again sorry it don't wash ..... there has to be a history story on this machine before you got it ....hmmmm ???

Of all the threads ever started here on HEF about 312's, never has there been a mention of these bad finals ...... "EVERY" piece of iron ever made of every brand will have an issue of one sort or another ...... I've owned mine for 14yrs and have had a few stupid things happen (including a complete 360 sommersault) and this tough little hoe refuses to give up. I owned a JD hoe prior to the Cat .... you don't want to get me going on that POS .... was it the machine or was it the Dealer support (probably) or was it a wanna be Hitachi where it was made with a JD engine (POS) in it ...... either way I got a REALLY bad taste in my mouth about ever owning anything JD Yellow ever again .... including JD skids (but that's another story) ........ to each his own ...... I own various brands of everything I have to be in business, so one can not say being brand orientated to everything Cat or Bcat or what ever.

In the issue of the final drive that has caused so much grief .... well ... fix it with a good reman it'll have a warranty do proper preventative maintenance, it'll go another life time for what you are using it for..... sure it costs bucks to fix but that's life owning equipment, all equipment ....Cat like all other manufacturers they out source things like finals, they are not that stupid to keep building 312's with repetative final drive issues made by others.

I am not affraid to keep owning my 312 because of what I have read here ..... or I would not sway someone away from buying one either........

Stumpjumper, you've been around the block once or twice, i'm sure, if you were to find a used hoe i'm pretty sure you would not be fooled by a fancy paint job and would check it out fully or go to a dealer support guy and get in writing any recall issues or what info they'd have to offer ..... maybe even oil samples or how ever your proto call to go and buy iron is.

There are as many threads or more here on HEF posted about Hitachi's or Kohmatsu's, Kobelco's, JD's about main pumps, secondary pumps, pilot controls, finals that pull more on one side than the other, cracked main frames, booms, sticks, hyd cyl's leaking, over heating, ect, ect, ect, ..... all to make us aware and NOT scare someone away from buying it.

Having said that I will check on Monday morning with my product support guy, if there is any bulletins on this issue .... and as anything with "T*ts, Tires, or Tracks" which all cause us problems we'll have to deal with it.................. just my vented .02 cents worth .........Cheers