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Case 646 Backhoe


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#1 jdr86 OFFLINE  

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Posted June 08, 2014 - 10:24 PM

 Gentlemen,

I bought a 646 backhoe and when I get it home I will be including some pictures.  The seller said it won't move and there is a great deal of foam coming from the hydraulic tank.  I suspect the wrong fluid and probably some linkage trouble.  It has been repowered with an onan performer 24 which (I am told) runs well.  It is missing the hood and the tower cover.  Rubber looks OK.  Someone cut an access hole into the floor deck to adjust the banana plate. Counting freight I have $3400.00 in it so far.  I am hoping this doesn't get much more expensive........I have heard so many good things about these that I decided to take the plunge.  Case Closed (GT talk member) said he would help me fix it up.


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#2 Texas Deere and Horse OFFLINE  

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Posted June 08, 2014 - 10:28 PM

I would check all fitting connections to make sure it's not sicking air into the pump. Foaming is usually caused by air or water in the oil. Sounds like it ought to be a strong machine.


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#3 BTS ONLINE  

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Posted June 08, 2014 - 10:34 PM

Sounds like a good project, Like Texas Deere and Horse said, I bet there is water in the hydraulics.
I have had lots of old tractor that spit foamy oil and it's water every time.

Can't wait to see pictures

Good luck!


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#4 Case-Closed OFFLINE  

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Posted June 08, 2014 - 10:36 PM

Hey JDR86!!! Not in your wildest dreams, I don't work on other peoples junk! only my own junk and I seem to have plenty of that with your help by the way. I would like to propose there be the addition of a NO Thanks button for those to the likes of JDR86!!!


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#5 jdr86 OFFLINE  

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Posted June 08, 2014 - 10:55 PM

Thanks to all, even case closed.  With friends like him who needs a rottweiler?

Good to know water is the likely culprit.  I am in Montana and am thinking about replacing the oil with ND30 weight.  I won't be using the tractor when the weather gets below freezing.  I have heard that 10W40 works as well.  Is the non detergent aspect a must?



#6 Case-Closed OFFLINE  

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Posted June 08, 2014 - 11:50 PM

I would be more concerned with taking your new find from the status of "yard art" to operational  before worrying about oil.


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#7 JDBrian OFFLINE  

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Posted June 09, 2014 - 06:31 AM

I would see what fluids Case now recommends for that tractor. You may be able to change to a hydraulic or hydrostatic tractor fluid and avoid problems with viscosity in the winter. A very nice machine. Just for reference there was a 646, repowered with a 20hp Honda, for sale here for 6900$. Your starting price of $3400 sounds good to me, particularly if that Onan is in good shape. 


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#8 jdr86 OFFLINE  

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Posted June 09, 2014 - 07:46 AM

That price comparison is encouraging JD.  I didn't think about the fact that oil recommendations have changed since the 70's when this one was new.



#9 jdr86 OFFLINE  

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Posted June 09, 2014 - 09:59 PM

Well, the tractor arrived today.  I think overall I am pleased with the purchase.  The onan performer starts and runs well, no smoke, smooth at idle and at full throttle.  It appears to be fairly new.  The retrofit was done leaving the pump in its original location.  They didn't reduce the length of the crankshaft and consequently the engine compartment is cramped between engine and oil tank.  The pictures show also that they didn't reroute the exhaust and that meant removing the hood for clearance.  The oil condition is terrible; I can see water floating on top and the level is low.  Banana plate will need replacement.  Left front wheel bearing is suspect.  Several steel lines were cut and sections of rubber hose were used to patch the job.  Both buckets need serious repair, maybe even replacement because they have rusted out.  I don't think the machine has been used very hard, the buckets appear to be original and the backhoe teeth are barely used, the cutting edge on the bucket is new.  From what I can tell the pins on the backhoe look to be in great shape.  Tractor model number is 646-75, does that mean year 1975?

Repair list will include new hoses and lines, rebuild of the curl cylinder, new oil and filters, fabrication of new hood and tower cover, probably new wheel bearings.  A nice winter project overall.

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#10 jdr86 OFFLINE  

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Posted June 09, 2014 - 10:03 PM

I forgot to mention that the steering wheel will have to go as well.  the steering wheel shaft needs a new lower bushing too.


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#11 Case-Closed OFFLINE  

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Posted June 09, 2014 - 11:48 PM

Best of all it's not in my shop.



#12 BTS ONLINE  

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Posted June 10, 2014 - 08:45 AM

:worshippy1:

Looks like a nice project, although I can't help but notice you didn't post any pictures of the backhoe! ?????? :(

The water might be your issue with it not moving, I'd get all that drained out as soon as you can.

Good luck! :thumbs:



#13 jdr86 OFFLINE  

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Posted June 10, 2014 - 08:57 AM

BTS,

I will post some pics of the backhoe tonight.  I ran out of energy and daylight yesterday.


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#14 BTS ONLINE  

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Posted June 10, 2014 - 01:08 PM

I guess I'll half to wait :ah_shoot:

Thanks :wave:



#15 jdr86 OFFLINE  

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Posted June 11, 2014 - 12:13 AM

Here are a few pictures of the backhoe.  I will order a new bananna plate assembly tomorrow.  I am thinking about replacing some of the hacked up steel hydraulic lines.  Are the steel lines hard to fabricate?  Do I need a special tool for creating the (JIC?) flare?  Some of the caveman modifications that were made irritate me.  I'm no artist but I'd like to think I do better work.

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