wdchyd
Elite Member
Hopefully you filled the case drain when you restarted the pump....:confused2:
it can lead to MORE damage if not
it can lead to MORE damage if not
Tractor squeals under load after getting warm
- Thread starter hlukeh
- Start date
- Views: 57289
Wakes
New member
What was the diagnosis
I have yet to fix it. It still operates as it did four years ago...
I have never let it squeal for more than a second, and anytime I use the tractor, I do it for short periods of time, and not during the heat of the day.
Is yours having a similar issue? I should probably follow wdchyd's advice and buy new plates and lap the rotating group surfaces.
I just noticed that this thread has over 17,000 views. This must be a very common problem!
Thanks again to everyone who has contributed suggestions and knowledge about the problem! I think this thread will be very helpful to people with similar problems for years to come!
Luke
thebean
New member
Hey All,
I have been lurking, reading, and re-reading this thread (it seems to be the most detailed and participated thread on the 1520 hst) for about a year.
My father bought a 1520 hst 4x4 in 1996 i believe. I grew up with that tractor and used it more than he did. I more or less ran a landscaping company in high school with this tractor. It has an FEL and BH and was an amazing machine. it began showing symptoms of the whine and lack of pull when hot but it wasn't bad at all. I changed the fluids and filters a few times as a kid. I went to university in 2004 and shortly after my dad fell ill, and lent the machine to our neighbor in exchange for having him plow snow/mow for the family business. skip a few years ahead and now the machine is useless. Barely even moves. So I am guessing this guy did something (likely a total lack of maintenance in combination with abuse) that just killed the transmission. It makes sense if you knew the guy. I recall clearly being angry that my dad let this guy use the machine because he is kind of a butterfingers dolt. Anyways i drained the oil after getting it back from him a while ago and it was dark and metallic. Bad news.
Now I am all growed up and am buying a house here in michigan. I would very much like to get this machine running again as it will save me thousands of dollars (need to install a french drain, clear some land, etc). I run a fabrication and powder coating facility and have two degrees in engineering, and multiple buddies who own machine shops of various levels of tolerances from precision grinding and lapping to structural steel fabricators. I know these transmissions aren't simple but the stubborn fix-it gremlin inside me is strong with the force and I am really considering rebuilding this transmission myself. Local tractor repair place quoted me 9k which seems steep.
The conclusion I have come to after reading through the grueling trials that Luke has recounted here is that I should be prepared to totally rebuild the HST pump and motor. It sounds to me (as others have stated) that doing a pressure only test on the feed pump is not very useful; even the smallest scratches or wear on seals will allow enough bypass in the HST to totally exceed the flow capacity of the feed pump which makes for problems. So Im looking at buying new plates, honing the pistons and barrels for the pump and motor, installing new seals and bearings. Im guessing this will push 1500 in cost which I am ok with. The price of these machines used is astronomical, I have found. At first I wasn't going to repair, because people on TBN keep saying to just buy another tractor if your hst is dead. But I havent found a comparable machine that I can touch for less than 7k, and my salvage value on this unit is probably only about 2k. So that leaves a pretty big repair cost window. Am I crazy?
I have been lurking, reading, and re-reading this thread (it seems to be the most detailed and participated thread on the 1520 hst) for about a year.
My father bought a 1520 hst 4x4 in 1996 i believe. I grew up with that tractor and used it more than he did. I more or less ran a landscaping company in high school with this tractor. It has an FEL and BH and was an amazing machine. it began showing symptoms of the whine and lack of pull when hot but it wasn't bad at all. I changed the fluids and filters a few times as a kid. I went to university in 2004 and shortly after my dad fell ill, and lent the machine to our neighbor in exchange for having him plow snow/mow for the family business. skip a few years ahead and now the machine is useless. Barely even moves. So I am guessing this guy did something (likely a total lack of maintenance in combination with abuse) that just killed the transmission. It makes sense if you knew the guy. I recall clearly being angry that my dad let this guy use the machine because he is kind of a butterfingers dolt. Anyways i drained the oil after getting it back from him a while ago and it was dark and metallic. Bad news.
Now I am all growed up and am buying a house here in michigan. I would very much like to get this machine running again as it will save me thousands of dollars (need to install a french drain, clear some land, etc). I run a fabrication and powder coating facility and have two degrees in engineering, and multiple buddies who own machine shops of various levels of tolerances from precision grinding and lapping to structural steel fabricators. I know these transmissions aren't simple but the stubborn fix-it gremlin inside me is strong with the force and I am really considering rebuilding this transmission myself. Local tractor repair place quoted me 9k which seems steep.
The conclusion I have come to after reading through the grueling trials that Luke has recounted here is that I should be prepared to totally rebuild the HST pump and motor. It sounds to me (as others have stated) that doing a pressure only test on the feed pump is not very useful; even the smallest scratches or wear on seals will allow enough bypass in the HST to totally exceed the flow capacity of the feed pump which makes for problems. So Im looking at buying new plates, honing the pistons and barrels for the pump and motor, installing new seals and bearings. Im guessing this will push 1500 in cost which I am ok with. The price of these machines used is astronomical, I have found. At first I wasn't going to repair, because people on TBN keep saying to just buy another tractor if your hst is dead. But I havent found a comparable machine that I can touch for less than 7k, and my salvage value on this unit is probably only about 2k. So that leaves a pretty big repair cost window. Am I crazy?
texasranger556
Platinum Member
Depending how bad the plates are you can resurface them and it will drive like new. I'd go that route first and make sure the rest of the machine is worth saving (busted gears or something expensive lurking behind a worn HST). This way you're only out time and virtually zero $ in parts.
If you get it apart and the pistons are shot, make the call then, but in the few I've been involved with just cleaning up the plates made a huge difference.
If you get it apart and the pistons are shot, make the call then, but in the few I've been involved with just cleaning up the plates made a huge difference.
thebean
New member
Ranger, thats good info, thanks! The rest of the machine is definitely worth saving. Engine runs like a top and rest of machine is in good order. Never had an issue aside from the HST. How finely did you resurface? Would a sharp round carbide in a tight lathe be good enough or should I have them lapped? What did you do?
texasranger556
Platinum Member
Others will probably disagree with the approach, but start with fine emery cloth (800 or 1000 if memory serves). Lay it on a piece of glass or perfectly flat machined surface, add some cutting oil and slowly take the scratches out by hand using a circular motion, being careful to apply even pressure on the plate. Obviously deeper scratches take longer than light ones, but in 1-2 hours you can do the pump and motor plates, plus piston faces. Once the surface looks free of the original scratches (will see some light scuffs from the emory cloth), move up to 2000 grit or finer, some even finish with bon ami to really make things smooth. My grandfather's 400 John Deere was done like this about 15 years ago and still works great pushing snow and cutting several acres of grass.
If your plates are scored to the point that the machine doesn't even move, it may be too far gone and you'd have to buy new plates since you'd have to remove too much material to clean them. Depends what your time is worth.
If your plates are scored to the point that the machine doesn't even move, it may be too far gone and you'd have to buy new plates since you'd have to remove too much material to clean them. Depends what your time is worth.
thebean
New member
I have repaired some 10,000psi hydraulics that were badly scored in the same manner with decent success. In all likelihood I would just machine up a lapping plate and mount everything up in the lathe to get a very flat uniform finish. I am also fine with buying new plates if they are badly worn. I am not however excited about the idea of buying new pistons and cylinder blocks, $$$.
texasranger556
Platinum Member
Haha I just realized that what we've done in the past is technically called hand lapping...I always thought lapping required some sort of machine. Doh :laughing:
My experience has been that the pump shows most of the wear since it turns at engine RPM while the motor turns slower and less often.
In any case, good luck!
My experience has been that the pump shows most of the wear since it turns at engine RPM while the motor turns slower and less often.
In any case, good luck!
thebean
New member
This forum is awesome. I have really learned a lot about this specific issue. thanks guys!
A PM from bill informed me that the barrels and pistons can't be lapped which makes sense because the seal is from a tolerance fit of the pistons in the bores so lapping would only make blow by worse. I priced out the parts and it comes to about $3000 to $3500 bucks. Not cheap but also only about half of the cost of a used equivalent machine. Finding something that has power steering, 4x4 etc is hard and everybody is asking so much for them.
A PM from bill informed me that the barrels and pistons can't be lapped which makes sense because the seal is from a tolerance fit of the pistons in the bores so lapping would only make blow by worse. I priced out the parts and it comes to about $3000 to $3500 bucks. Not cheap but also only about half of the cost of a used equivalent machine. Finding something that has power steering, 4x4 etc is hard and everybody is asking so much for them.