New Holland TC29D hydraulic control valve spool noisy

[Mtsoxfan]

Always had the squeal until fluid warmed up. At times, when fluid low from leak, the valve spool would squawk. I changed the fluid and filters out as maintenance, now, it squawks more frequently when hot or cold. tried running the hydraulics thinking it was air cavitation, but didn't help. Fluid level is fine, no air bubblers. Repair manual doesn't cover the noise. The squawk is usually when the bucket curl reaches limit. Anytime I curl and lower at same time, no squawk until the up/down reaches its limit and I'm still curling. The is no squawk when up/down reaches limit on its own. Any suggestions? tranny works fine.

 

[Harry in Ky]

Your description of your symptoms seems a bit vague to me, but then again sometimes I catch on a bit slow. It almost sounds like a simple relief valve squeal and you don't recognize it as such. Please correct me if I'm wrong. Does your tractor plumbing look anything like this? If yes, can you say for sure the sound comes from the loader valve? There are (at least) two relief valves in this system. Main system relief is in the diverter block, and apparently there is also one in the loader valve. Some system pressure checks might be in order here, but you might also try adjusting the loader valve relief up a half turn or two to see what effect that has. I can't see why that would hurt anything as the main relief is still in play.

New Holland Agriculture | Schematic, Manuals, Specifications and Diagrams for two-spool remote control valve & piping kit, prince valve #hc-v-ab10 & #hc-v-ae35 | MyCNH US Store

Find schematics, manuals, specifications and diagrams for TWO-SPOOL REMOTE CONTROL VALVE & PIPING KIT, PRINCE VALVE #HC-V-AB10 & #HC-V-AE35. Find genuine OEM parts for your needs.

www.mycnhstore.com

 

[Mtsoxfan]

I know this is a niche issue on a niche tractor...
It's hard to tell from the picture, and I do have a service manual to view.
Terminology is subjective, a squeal is normal to some degree on my tractor. The squawk is abraisive and sounds like my tractor is telling me something is wrong.
Curling bucket only, squawk sometimes happens when limit reached. Normally quiet or a very light squeal. Using multifunction (curl and lower) at the same time, all is normal if curl ends first, but will squawk when lower function complete. This squawk doesn't happen all the time, it can happen cold or warm. I'm thinking air, but have put 7 hours or so since changing hydraulic fluid.
It doesn't sound like it's coming from engine mounted pump. Sound seems to come from under the control stick/ filter area.

 

[Harry in Ky]

Again, a relief valve "squawk" is to be expected when a cylinder reaches the end of stroke and a valve is still active. No matter how many functions you have going on, as long as there is somewhere for oil to flow things should be quiet. When that ends and a valve is still active, something has to give. The relief is designed for that. So far here, I'm having a hard time seeing a problem. I can't see air being a factor. Air in a hydraulic system has it's effects, yes, but this wouldn't be one of them. Typically when you hear a relief valve that tells you it's time to let go of the valve.

 

[oldnslo]

If air going thru pump the pump would be very noisy anytime trying move a load under pressure and not just when a cylinder bottoms out. This noise would be at the pump. Like Harry states sounds like a relief valve doing its job. Note: If like Harry stated you have a main relief in diverter block and also a relief in the loader valve they can “talk” to each other if set at similar pressures. General rule of thumb is you want relief valves to be set a minimum of 200 PSI difference.

 

[Mtsoxfan]

It seems like I'd have to post a video. Squeal is one thing at limits end, occasional, loud, disturbing squawk is another. Used to only squawk when low on fluid. And until the leak developed, there was never a squawk, just a squeal when limits reached.
I appreciate you reaching out, as it's tough to find anyone, including dealer willing to work on this compact tractor. One dealer said bring it in, will fit in when we can, but can expect to be 6 months to a year. UGH...

 

[Mtsoxfan]

If air going thru pump the pump would be very noisy anytime trying move a load under pressure and not just when a cylinder bottoms out. This noise would be at the pump. Like Harry states sounds like a relief valve doing its job. Note: If like Harry stated you have a main relief in diverter block and also a relief in the loader valve they can “talk” to each other if set at similar pressures. General rule of thumb is you want relief valves to be set a minimum of 200 PSI difference.

Thanks to you both. Seems like I need to buy some gauges and start some investigations.
I bought used, but have changed out both hyd filters at each 300 hours of use per manufacturer.
I do have a service manual, but I'm sure I will have some more detailed questions to ask when I need to be pushed in the right direction.

 

[Harry in Ky]

I doubt a video here would be of much use. The sound you hear on the tractor has a location. On a speaker out here it's of little help. What was the leak involved?

 

[Mtsoxfan]

Still have leak, can't find anyone to work on it as it requires a tractor split according to service manual, a seal where tranny meets up with engine. Sound location is in the area of large filter and control stick. I only figured the video could demonstrate the noise difference between squeal and squawk. Although, I've never looked into where the squeal came from because I considered it normal.

 

[5030]

Interesting. I too have a hydraulic squeal in my M9 open station but I know what the offending part is, it's the orbital steering pump and while it's not leaking, it's noisy but I'll run it until it pukes because one, it's expensive to replace and two, it's not rebuildable so it remains until it pukes and then I'll spring for a new one. It's about a grand. I just ignore it.

Least it's easy to access. Under the dash cover and I can do it myself.