Ford loader backhoe hydraulics problem.

I have a Ford Loader Backhoe:
Numbers stamped on the Bell housing above the starter are:
FF311S
1J08B
*C673302*

It has 750 on the backhoe. I was told by a New Holland Parts guy that the Model # FF311S meant it was a 755.

The problem I'm having with it is the system relief valve n the loader section is bypassing oil. I took it apart and it looks like some of the o rings are damaged. New Holland is absolutely of no help. Cain't get the valve or the o ring kit. Their parts catalog does show a break down of the valve with all the parts. Some of the o rings have specs. But they don't match anything I have found at o-ring suppliers. Ford's specs are in thousandths of an inch where those available from stores are in increments of 1/16th inch. I need very badly to fix this valve or find a replacement. Any help or advice will be appreciated.
Wally Smith

Take the relief valve to a reputable hydraulic shop. Also grab any numbers you can find on the control valve itself. They should be able to help you.

FF3 is on the page that was missing from my reference when I received it. The 3 in the third spot should mean that it was made during the same time frame as the xx10 series ag tractors, as they all seem to have a 3 in that third spot as well, so the date code of 1J08B should mean September 8, 1981, and that serial number, *C673302*, agrees in that it's a 1981 serial number.

There was a 750 Tractor Loader Backhoe model made, but that model was made from 1975-1980 when the x600 ag tractors were being made so that doesn't match up with the date code and serial number. The 755 industrial backhoe tractor was made from 1978 through 1983, so that agrees with the date code and serial number. So the 750 on the backhoe might mean that it is a 755 model tractor with a backhoe transplanted from a 750, or it could be a 750 tractor with a transmission transplanted from a 755.

Look on the under side of the right hood panel, up above the battery and see if there's a foil sticker there with similar numbers and post them back here and we might be able to help more. If those numbers match what's stamped into the trans casing then it's likely the tractors is a 755 and the backhoe was swapped from a 750. If the numbers under the hood don't match what's stamped on the trans casing, then the transmission was most likely transplanted from another tractor.

You can also check the date codes on the individual components to come to a consensus on what the majority of the tractor is.

Also, the loader itself might still have a metal tag somewhere on the loader frame with a model number on it, which should look like I9-xxx. If you can find that number post it back here and we can help identify the loader itself.

As Bern said, you should be able to take the control valve to any good local hydraulic shop and they should be able to get you matching o-rings.

Thanks for the replies. I did take the valve to a couple of local hydraulic shops. Didn't get much help. I also had it put on the used parts hotline. No help there either.

I am inclined to believe now that it is a 755 with a 750 back hoe. But I still need to find a fix or replacement for this relief valve. Here is what New Holland's online parts catalog says:

System relief valve
Model No. FF311s
Production Code 1J08B
Serial No. C673302

40 E1NNA896AA HYDRAULIC VALVE Valve Assy., Main Relief, Details Not Released, Includes: Body, Poppet & Ref. 41 thru 54

41 7705190 CAP Pilot Relief, Years: -31-DEC-81

42 7705190 GASKET Relief, Years: -31-DEC-81

43 7705188 SCREW,1/2" - 20 x 15/16" Pilot Relief Adjusting, Years: -31-DEC-81

44 7705180 SPRING Pilot, Years: -31-DEC-81

45 89626929 O-RING 90 Duro, 1.048" ID x .116" Thk, Years: -31-DEC-81

46 7705181 WASHER Back-Up, Years: -31-DEC-81

47 128999 O-RING,0.424" ID x 0.63" OD x 0.103" -111, 70 Duro, .424" ID x .103" Thk, Years: -31-DEC-81

48 7705182 RING Round Section, Years: -31-DEC-81

49 7705184 PIN Relief, Years: -31-DEC-81

50 7705185 SPRING Pilot Relief Piston, Years: -31-DEC-81

51 7705183 PISTON Main Pilot Relief, Years: -31-DEC-81

52 7705186 CYLINDER Main Pilot Relief, Years: -31-DEC-81

53 293428 BACK-UP RING Back-Up

54 9861411 O-RING,0.864" ID x 1.004" OD x 0.07" 90 Duro, .864" ID x .070" Thk

I would like to find another valve, but I would try replacing all the o rings and backup rings if I could find them.

I suspect that either your local hydraulic shops are ignorant, or just don't want to work very hard for a few dollars of profit on some o-rings. I can't believe that Ford would use a valve that has o-rings custom made just for them.

I would keep trying hydraulic shops, making phone calls to shops in larger cities.

Sorry that I am not of more help here, but it's what I would do.

Those three O-Ring part numbers that you listed should be available through any New Holland dealer now that you've got the part numbers. If not you can get them on line.

partspring.com shows 490 available of the first one and 1000+ of the other two. But they only sell them in bags of 10 each at $5.00 to $8.50 per bag.

Messicks sells them individually for less than a dollar a piece, and they show all of them in stock as well, but at much smaller quantities, (8, 40 & 11).

They are standard orings. Here is what I come up with. #45/914 #45/116 #47/111 #54/020 and all backups will be the same as oring size except for the 914 witch is a boss oring there is a backup that will work with it. I do this most every day working at shop that does hyd cyls and non oem pumps/motors.

Thank you Shaun Wallace for cluing me in on O Ring sizes. I now understand a lot more about O Ring terminology. AS568 numbers, durometer numbers and types of material. I think I found the O Rings I needed at:
http://www.oringsusa.com/catalog/index.php

Now I have another more serious problem with this valve. With all the different people who has messed with it, me included. There are now two missing parts. # 48 7705182 Ring and #49 7705184 pin.

No one seems to have these.

So I am still SOL.