Problems with 3 point hitch IH 424

[espotony]

I'm having problems with the hitch on a 1965 gas IH 424 with PS and FEL. Previously, the hitch was rock-solid. It would hold up a weight box loaded with stone indefinitely. Recently, without warning, it now hiccups - that is, it raises, then drops, then raises, continuously. Whenever it does this, the steering wheel also pulses. Previously, there was no issue with the steering. If the lift is raised, then the engine turned off and the isolator valve turned in, the hitch will drop the load in about 1 minute. If the engine is running and the isolator valve is closed, the pump begins to scream, so I feel that the isolator valve is working correctly. The full/half-speed valve on the left side also seems to work properly. I'm pretty good with engines but have no experience with hydraulics, so I bought the factory manual and hired a well-recommended mechanic who helped me with this. We removed the hitch and put a new seal on the piston. Neither the cylinder nor piston showed any signs of scoring. The filter in the lift housing was clean, but I flushed it anyway. The oil appeared normal-no water or signs of foaming. No broken parts or metal chips in the housing. Additionally, we replaced all the O-rings on the cylinder head, including the large one that seals the cylinder. I feel very comfortable that the work that was done was done correctly and well. After reassembly, there was no change to the hitch behavior. However, the FEL, which had previously needed engine revving to lift a load and would slowly drop the bucket after turning off the tractor, was a great deal more solid and would hold the bucket up for several hours. It would also lift a modest load with the engine at idle and would lift a heavy load effortlessly which was a great and unexpected improvement in its performance. So we disassembled the hitch and this time cleaned and/or checked the 4 valves in the cylinder head. All were cleaned and new O-rings installed. Nothing seemed worn or damaged with the spools or the relief valve. The draft piston showed signs of very light rubbing, but no scores or wear marks. Everything else looked like new, O-rings excepted, most of which had flattened edges and had gotten a bit hard. We also disassembled the little relief valve in the piston and I think, replaced an o-ring. The tiny check ball is certainly present. We used a compressor to blow out the passage and pretty much confirmed that it would only pass air in one direction. There doesn't seem to be any adjustment in the linkage for the draft and position valves. Everything with the linkage appeared normal-no bends, scores etc. We carefully reassembled, making sure that all the check balls and springs, etc were present and in their proper location, verified by comparison with the factory manual. Started it up and everything seemed A-OK, except that after turning off the engine, it would drop the load in about 5 minutes. As I mentioned, previously, the hitch was rock solid. Next day, all problems returned. A curious thing which I can't explain is that FEL which draws hydraulic oil from the differential housing is returning it to the lift housing. There doesn't appear to be any way for hydraulic oil to return to the differential. I should mention that the tractor has 2 hydraulic pumps, one for the FEL and a 2nd for the hitch and power steering. Both pumps seem to be OK, as both the hitch and the FEL will lift a load properly. The hitch just will not hold it up. I have owned this tractor for about 5 years but have been familiar with it since it was new. It did receive a new front pump about 10 years ago. For its age the tractor has seen modest use and has not been abused. Besides the pump, I don't think it has suffered any major problems and it has received regular maintenance. There is a large additional hydraulic oil filter on the right side of the engine which I have not yet changed/cleaned but after all this I'm skeptical that it is the problem. I'm flirting with the idea that the diverter valve in the power steering might be involved. This is a long post but I thought if I included every conceivable clue, it would be helpful. I and my mechanic are otherwise out of ideas. I sure hope one of you with experience can help. Thanks so much.
Tony

 

[DLTTrekkers]

Did you remove the lowering spool and replace all those small o- rings and check the valveseats ?

 

[DLTTrekkers]

 

[DLTTrekkers]

It is behind that small loose piston with the small spring operating by a lever as you look inside when you remove the topcover and drain some oil

 

[DLTTrekkers]

 

[DLTTrekkers]

Look at numbers 15...16 and 17
To remove use a soft punch and tap it out to the other side making sure of the correct order it came out

 

[espotony]

Thank you for the tip. The hitch will have to come out again. I thought that we had changed all the o-rings on all the valves, but we did not remove any using a punch, so we might have missed this. All the other valve/spool combos came out by removing snap rings or unscrewing, so we might have missed this. We're getting pretty good at taking the hitch off! I will not be able to try this for 2-3 weeks due to other commitments. I appreciate your taking a shot at this.
Tony

 

[espotony]

The hitch came out for the 4th or 5th time. The lowering valve and all the o-rings on that valve were replaced. All the o-rings on the cylinder head were replaced. The seal on the piston was replaced. This is an old style piston and it has some kind of a thermal relief valve on it. The o-ring in that valve was replaced as well. The hitch is still stuttering. Does anyone know anything about that thermal relief valve? IH has a newer style piston with a different seal on it. The new style piston may or may not have the relief valve. Since every other moving part on the hitch has been checked out, I am out of options. My last ditch plan is to replace the piston with a new style piston. Any other ideas will be greatly appreciated.

 

[DLTTrekkers]

Be carefull for problems you build in . Then do not be blinded be a hidraulicpump not good enouht to lift heavy implements and that the 3point hidge not going in neutral. That will leave the 3point hidge still triing to lift and when you slowdown the engine rpm s the oil will flow in reverse back to the reservoire and lower the implement. Be openminded when working on hydraulics!

 

[DLTTrekkers]

QTED FROM MANUAL......Screw in the isolatorvalve and if the liftarms stop falling , the leak is in the control valve . If the arms continue falling, the leak is in the piston

 

[DLTTrekkers]

Uncouple your powersteering and test your hidge. This test wil let you know if the probleme disappeare ?

 

[espotony]

First of all, I want to thank DLTTrekkers for pointing me in the right direction. You were absolutely ON THE MARK!! For all who might have followed this thread, I would like to post the actual solution, so that others may learn from my mistakes. The original problem was that the lift was hiccuping, that is, it would raise the load, then let it down a few inches, then raise it again, repeating this cycle endlessly. On the first disassembly, we found a very small crack in the plastic piston ring, which we thought might be responsible for the problem. We also disassembled the thermo relief valve and cleaned and checked it. And there was the problem, which we created ourselves. When we reassembled the relief valve, we put in the ball follower backwards. It was an honest mistake, because the follower had a shoulder which fit nicely inside the spring. The result of this backward assembly was that the ball had no pressure on it, so the relief valve was always open. This produced the exact same symptoms as before the repair, but from a completely different cause. All the subsequent work, all the new parts and all the o-rings, not to mention the time spent worrying over this and the endless internet searches were for naught. Following DLTTrekkers advice, we took it apart one more time, expecting to find a failed piston ring, a minute crack in the piston or the cylinder or some other issue we had missed. We were very careful and looked at EVERYTHING critically. If the isolator valve was shut and the lift lowered after the tractor was shut down, the cause HAD to be in the cylinder. We took apart the relief valve one more time and then it hit us that if the follower was installed backwards, the ball had no pressure to hold the valve shut and so the relief valve was always open. We verified our guess by consulting a picture in the manual. Well, the hitch is rock-solid once again. My thanks to all who helped out on this. Remember that you can make your own problems. Not every problem is caused by a failed part. Sometimes we are our own worst enemies.

 

[DLTTrekkers]

After reading throu your first post and not seeing anything about the lowering valve ...that was my first response...then I start thinking about a bouldin mistake . I am glad your tractor is as good as new !

 

[DLTTrekkers]

After reading throu your first post and not seeing anything about the lowering valve ...that was my first response...then I start thinking about a bouldin mistake . I am glad your tractor is as good as new !

And this coming from my country...sunny South Africa at the southern tip of Africa