To rebuild or not to rebuild.........

[tlb]

Hi All,
I'm looking for advice/suggestions for some issues occurring with my PT425, summarized as follows:
1) excess oil in engine/hydraulics compartment.
2) whining/clacking noise coming from either rear of engine or hydraulic pump
3) lift-arm goes up fine (quick), but down very slowly and in jerking steps (with no load on lift-arms)
4) jumping out of float regularly.

For #1 above, over the past 6 months I've noticed what appears to be oil (engine or hydraulic, not sure) on the engine case and bottom of engine compartment. It is not pools of oil because when I mow, there is enough dust generated that gets mixed with the oil and just forms a blackish layer of crud on everything. Looks to me as a leak around the crankcase gaskets. Always check engine oil level and Hydraulic oil level before each use and the levels seem to be good, although Hydraulic oil level was a little low last time. One other note, up until recently (summer 2019), I never saw oil on the garage floor due to the tractor. Last fall, I had to put cardboard under the tractor to catch oil, though it is not much.

For #2 above, I first noticed noise last fall. The loudness level varies a little, sometime not very noticeable, other times very noticeable. My first though was valves tapping but engine oil level was fine. For my PT425 vintage (2002), the engine is mid-mounted and VVP is mounted at rear of tractor.

For #3 above, this issue just happened. The tractor was parked in the garage for about 2 months and I took it out over the weekend for some light work. Without a bucket or mower (load) on the front-end, the lift arms did not want to go down, but no problem going up. Putting a load on the lift arms (bucket), going up or down was ok. I assume bucket weight helps to lowered the lift arms.

For #4 above, this seems to be an intermittent issue. When the tractor sits a while (>month), it does not want to stay in float the next time I use the mower. After maybe 30 minutes of use, float works better.

One thing I am considering is taking the tractor to Power-Trac for refurb. Has anyone done this recently, and what might be the cost, and what all does Power-Trac do?
This option is expensive for shipping since I live in Central Texas. Shipping estimate is ~$1200 each way, and I have to drop off/pick up the tractor in Waco (closest terminal) which is >2 hours away.

Another option is local company doing refurb (engine and/or Hyd pumps). However, I have not found a good company that will do this. My past experience with lawnmower repair companies is they don't do Hydraulics or want to fool with a 'non-standard' product. I did have a local lawnmower company replace the head gaskets about 12 years ago but the engine technician complained about how hard it was to work in the tight engine compartment.

And finally, I could attempt repairs myself. I'm not confident in my abilities, having only changed a few failed wheel motors, mower spindles, fuses, and key-switch over the years. I guess on the positive side, the tractor has been fairly reliable considering the amount of use it has endured in 18 years with no major breakdowns.

Thanks in Advance,
-Tim

 

[MossRoad]

For #1, I'd clean out your engine compartment as best as possible, then add leak detector dye to your hydraulic oil. Run the machine a while, then use a black light (sometimes furnished with the dye kit) in a darkened garage and see where the leak(s) are coming from. If you see oil but it's not luminescing with the black light, then it's engine oil.

For #2, clacking in hydraulics that sounds like gravel in a tumbler is usually cavitation. Does the noise only happen when you move the machine forward or backwards, or is it there when standing still as well?

For #3, I suspect your up/down valve has some crud in it. I base this on my own observations as such: when I have no implement on my FEL arms, and put the FEL in float with the machine running, the lift arms will go down very slowly, and never reach the ground. If the tractor is off, then putting it in float will let the arms go all the way down with no implement on them. Also, with no implement on the ground, and the FEL all the way down, and in float, if I start the tractor, the FEL arms will raise off the ground a bit.

Combine that with your #4 issue with float, and that also points to the valve for the up/down function of the FEL.

So, I'd start with cleaning out the valve body if your comfortable with doing that kind of work, and see how that goes.

 

[tlb]

Thanks for the response.
Good idea for #1.
For #2, it is always there, even when idling. I am familiar with the cavitation noise, it seems to only occur when a) backing up, and 2) when Hyd oil is cold. Could there be another reason for cavitation and what is the typical remedy?
For #3/4, where are the up/down valves? I think your machine is similar vintage as mine.
-Tim

 

[tlb]

Is this it (lift arm valve)?

 

[marrt]

How many hours do you have on the tractor?

1. This is very common. I don't think I've every seen an older PT without some oil in the tub. This can come from a variety of source...spills when changing filters, spills when changing engine oil, leaks around fittings, etc. If it's from the hydraulic system, you'll usually know it (you'll find a lot of oil). If it's from the engine, keep an eye on the levels to gauge how much you may be losing. Unless you're seeing fresh oil, I wouldn't worry too much about it given the age of your tractor.

2. Again, may be normal. All hydraulic units whine a bit. Clacking is more worrisome if you're sure it's coming from a hydraulic pump. How is the pushing power of the tractor? If it's weak, the you may have a pump problem. You can always measure the charge pump pressure. In my opinion, Power Trac pumps are a "wear item" and it's normal to rebuild them after 1000 hours or so (or, sometimes, way less hours). This could have been avoided with a better hydraulic circuit design. However, the price would go up. So, it's a tradeoff.

3. and 4. I agree with Moss. Ether way, this isn't something to worry about unless it bugs you. The failure to stay in float is pretty common. Bungee cords can help.

Taking the tractor to PT for a rebuild, given your location, would be very expensive. Of course, it all depends on what you're willing to spend.

Here's what I'd do if deciding to rebuild rather than chase every problem:

A. Depending on engine hours, just pull the old engine and buy a new one (about $2500). You could rebuild it...but it sounds like you don't have the experience, so it would be a hassle to rebuild. Of course, this assume you need an engine.

B. Pull the main pump and send it to PT for a rebuild (about $1500 depending on what they find). Carefully mark and cap all hydraulic lines with proper metal JIC plugs and caps (get them on ebay). You may want to send the lift valve for the arms too (I would). Pack everything is a Home Depot 5 gallon bucket, with properly secured lid, for shipping.

C. While you have to engine and main pump out, power wash the tub and carefully check for hose wear. Replace as necessary. Snug up every fitting you can reach.

D. Drain and replace the hydraulic tank. I'd use Shell Rotella diesel oil (more antiwear additives). Any synthetic is a good choice too.

E. Put everything back together and enjoy.

A helper, engine hoist (cherry picker), and lots of pictures make everything go smoother. You'd save A LOT versus the "send it to PT" option. Don't get me wrong...I once sent a tractor to them for an inspection and repair as necessary. However, I live in Virginia and the seller was paying part of the cost. I know a lot more about the tractor now than I did then. I rebuilt one of my 425's just last year. It's easier than you think.

 

[ponytug]

Just a couple of thoughts. You might think about putting a fresh hydraulic oil filter in. It might explain the whine and clacking. Since #3, the valve issue sounds like it may be caused by having some crud in it, perhaps the filter has crud in it. I had the reverse problem (fast leak down), and cleaned the check valve in the valve block, which fixed the problem for me. You might ask Terry.

Good luck!

All the best, Peter

 

[m5040]

When a hyd cylinder is "jerky" when lowering, it is a sign of having air/air-rated oil (bubbles in oil), so is a noisy hydraulic pump. This can come from as simple as a low hyd oil level or a loose hose clamp on a suction side hose or clogged filter. It is very damaging to the pump. As stated, change your hydraulic filter with the proper part number and bleed it as PT advises. My advice is don't ignore it.
Trace the suction side hoses and make sure there is zero leaks and all fittings are tight. Wash out the oil and find the leaks (at least in the suctions side) - remember it will only leak with machine off. Not to get to simple, but think of trying to drink a milkshake with a hole punched in your straw.....

 

[barrell]

most John Deere dealers can handle anything with Hydraulics