Just got a #7 backhoe and need some advice

dsmau · Dec 31, 2010

As some of you might recollect, I have been looking for a #7 backhoe for my 855 and I finally pulled the trigger on a fairly nice unit on CL in Vermont.

Now, I am not sure what age it is and I can't find the serial number tag. Could someone who has one tell me where it is hiding? I will then order the right manuals and decide on how I go about fixing a few leaks in the control valves. Besides that, there are no leaks anywhere; the cylinders are all straight and intact although one of the stabilizers seems weak going down. Not too worried about it for now but I will probably address that after the valve is back in shape.

If I knew the age, it would be easier to decide on which seal kit to get and how many valves to work on preventively. All I know is that the tractor it was on (855 TLB with 600 hours) was recently bought at an auction and the tractor is a 1986. I do not think the backhoe is as old as the tractor because the tractor does not have the taller ROPS but I might be wrong. The tractor looked really nice for a 1986 with still its original paint. It was stored inside...

Thanks for you help!

bullbreaker · Dec 31, 2010

Heres some info/specs from TD.
Boone
TractorData.com John Deere 855 tractor attachments information

gator · Dec 31, 2010

Just walked out and looked at mine (JD7 backhoe on JD 750) and could not find an id plate on it. Only thing I found was black numbers painted on left side of boom (first stick that swivel cylinders attach to) that start with 1-PT8XXXX, don't know for sure but maybe thats the S/N of it. On right side in black letters is MADE IN THE USA.

dsmau · Dec 31, 2010

gator said:
Just walked out and looked at mine (JD7 backhoe on JD 750) and could not find an id plate on it. Only thing I found was black numbers painted on left side of boom (first stick that swivel cylinders attach to) that start with 1-PT8XXXX, don't know for sure but maybe thats the S/N of it. On right side in black letters is MADE IN THE USA.

Thanks for checking Gator. I don't see any black writing on mine but I think I have seen pictures of backhoes with painted letters like that. Any other ideas? I don't think it has ever been repainted.

dsmau · Jan 1, 2011

K7LN said:
Forgive the poor picture that I took freehand in the cold, but mine is on the right stabilizer facing the rear.

Thanks a lot K7LN. I see now where it was. I see the a cleaner spot where it used to be. I will quit looking for it...

From looking at the parts diagram on JDparts, I figure my model is an earlier one so probably like 86-92 is my guess.

Should I replace all spool seals at once? At least 3 are leaking from what I see. I will try to post pictures soon. Also, I am not sure which seals to order on JD parts but I will analyze more and perhaps take it partly apart to see what I should replace in there.

Don87 · Jan 2, 2011

Is it possible to do 'backtracking' of the backhoe to find out where it was purchased?

The original dealer would probably have a record of the original sale with the serial number.

dsmau · Jan 2, 2011

Don87 said:
Is it possible to do 'backtracking' of the backhoe to find out where it was purchased?

The original dealer would probably have a record of the original sale with the serial number.

Good idea. I am checking into in.

In the meantime, I took one spool apart and found the reason why it is leaking. The O-ring is broken in 2 places. Not cut through but the outside of it is quite damaged and seems to have pushed and bent the bracket and washer that holds it in place. Is it is the normal way an O-ring ages? I will go by the local hydraulic shop tomorrow and pickup 12 O-rings and replace them all(top and bottom). They look quite standard with 3/4" inside diameter and 1" outside. I will reuse the old washer and bracket after I straighten them a bit. I will try to post pictures to show better what I mean.

Let me know if any of you have a better suggestion. I know next to nothing in hydraulics and I am learning as I go.

Since I have a pressure gauge now (since rising the relief valve on the tractor), I was thinking of testing pressure in all hoses but I will do that after I get the technical manuals...when I know what they should be but my first priority is to stop the leaks.

955er · Jan 3, 2011

Make sure you look into a subframe for that #7. DFKrug has a fantastic thread on the need for, and construction of. I also believe he references the x55 series multiple times in the thread.

dsmau · Jan 3, 2011

955er said:
Make sure you look into a subframe for that #7. DFKrug has a fantastic thread on the need for, and construction of. I also believe he references the x55 series multiple times in the thread.

I probably forgot to mention that the backhoe is already frame mounted coming from a 855 to a 855. It went straight on my machine so it is already on there! Now I am doing some maintenance until the spring comes...

dsmau · Jan 3, 2011

I am changing the O-rings tonight. I got all 12 for 8 dollars so I am replacing them all. So far 4 out of the 6 top ones were visibly damaged. The bottom ones don't seem to be in bad shape but I am replacing them anyway.

Question: Is there supposed to be oil put back in the cup where the bottom O-ring is with the spring? It seems like no oil is going in there so it could rust if I don't put something back in there.
Thanks.