[timf]

About 3 1/2 years ago I decided to install a rear PTO on my 455. At the time the install seemed to go well, however, about 6 months later I found that my snowblower just didn't have much power. In fact, I got a rock got in the snowblower fan and it didn't break the shear bolt. I soon realized that the hydraulic pressure was dropping gradually as the machine warmed up. The following spring, I took the rear PTO cover off, pulled and replace the PTO brake and pressure plate components, replaced all the seals and re-installed the rear PTO cover. The problem continued. For the next year, I must have removed, checked and reinstalled the rear PTO cover a half dozen times each time a new idea came to mind but still no resolution. About 1 year ago, another member here, reported a similar problem due to the hydraulic fluid boiling. He was optimistic that cleaning debris trapped in the radiator screen would resolve his problem. I checked my radiator screen and found a small amount of debris and for the past year have kept a watch on the screen and radiator on my 455....still no positive results but no signs of hydraulic fluid boiling.

About a month ago, I decided to search the web to see there was anything new regarding my PTO issue. Low and behold, I found a similar problem claiming the problem was with the oval seal on the rear PTO cover not maintaining its shape during install, thereby, allowing fluid to pass. I didn't think that could be my problem since the oval seal was never deformed when I took the rear PTO cover off and it wouldn't explain why I had good pressure when first starting out but the pressure would drop as the machine warmed up. I decided to try it anyway as I had developed a minor leak in the sealant at the bottom of the rear PTO cover. To my pleasant surprise, I found the oval seal in the deformed shape described by the original poster. As the original poster suggested, I placed a paper clip into the new oval seal to maintain the shape of the seal during install and it has worked well so far.... the blower appears to have full power now. Per the original poster, the standard PTO cover has tabs / fingers to maintain the oval seal shape, whereas, the rear PTO cover does not, hence the need for the paper clib to insure the seal maintains its shape during install. As the machine warms up, the viscosity of the hydraulic fluid decreases, hence, the gradual decrease in PTO pressure.

I surely hope this saves someone else time, frustration and money trying to resolve a PTO pressure problem with their 425, 445 or 455.

Tim

 

[bobstillwagon]

Thanks for posting this info Tim. Not sure it is clear to me what the paper clip does but maybe it will be if this work is ever needed on my unit.

 

[jdmaninlouky]

Another thanks Tim -

When I install my rear PTO now , I will pay special attention to that particular seal so as not to have future problems .

Dave

 

[timf]

Bob,
A standard paper clip will fit nicely (might be a little forming necessary) inside the circumference of the oval seal. The paper clip keeps the long sides of the oval seal from caving in before the rear PTO cover is installed and secured. The ledge the seal sits on is only as wide as the seal, therefore, if the sides of the seal move inwards at all, hydraulic fluid will escape past the seal into the transmission sump. The amount of fluid the seeps past the seal increases as the fluid warms up, thereby, reducing the PTO pressure causing the PTO clutch and brake assemblies to not work.

 

[timf]

I didn't think the picture I took of the failing /deformed seal was very clear but it looks better than I expected. Hopefully this will clear up the need for the paper clip when installing oval seal in the rear PTO cover.

 

[arnie]

Tim, does the paper clip stay in there after reassembly then? and won't it come out with fluid passing by it?

 

[timf]

Arnie,
What is hard to see in the picture is that there is a channel under the paper clip through which the majority of fluid flows. From what I can tell there is enough pressure being applied by the paper clip that it will probably stay in place, however, even if it doesn't, I don't think there could ever be enough flow to cause the paper clip to contort in two perpendicular 90 degree bends for it to pass (notice the entrance and exit ports visible at each end of the paper clip, the two test ports [screw heads at the bottom] which access the fluid passage ways [ extending vertically above and behind the seal]. Actually, I don't think I could force the paper clip through the ports even if I used a pair of needle nose pliers to try and drive the paper clip through the ports and up the channel. The original poster that discovered and solutioned the problem hasn't had a problem and after 2.5 hours of operation (albeit not much) I haven't had a problem either.

Tim

 

[jdmaninlouky]

Great info Tim -

Those pics' make everything clear as a bell as to what the problem area is , and why it becomes the problem . Looks like Tuff-Torq could have / should have done a better job with the engineering of that seal interface , Thanks very much for taking the time to post this !!! Dave

 

[timf]

David,
It would seem to be a design issue. FWIW, both the original poster and myself are adding an early model rear PTO kit to later model machines. Both of our original rear transmission covers have tabs /fingers to prevent this problem. What I don't know is, if we had installed later model rear PTO kits, would those have had the same tabs /fingers as the standard rear transmission cover? My suggestion would be for anyone removing and/or replacing either the standard or PTO versions of the transmission covers to keep a look out for this issue...it may not just be the earlier rear PTO covers that have the potential for this problem.

The good news is that since no one else has ever reported this condition before the take away is that there are either few machines with rear PTOs and/or the rear PTOs are mechanically solid assemblies.

Timf

 

[jdmaninlouky]

Thanks again Tim .

I'm doing the opposite , in that I am installing the later model - '95> rear pto on a '93 445 . Your info will be invaluable to me while doing the retro-fit .
BREAK - I just went out and looked at my late model kit , And it has the small retention tabs in the casting to hold the O-ring in place . So it looks like I won't need a paper clip ..,

BUT .., what I do need is the old style wiring harness JD part # AM121071 (NOT USED ON '95>),if either of you guys have one with your kits that you would sell me . I have the jumper wiring harness # AM 121061 that is required for the later model tractors if you need one . Sell me the wiring harness (if you have one) , and I'll give you the jumper harness for free including shipping .

Please let me know Tim . Thanks ; Dave

 

[timf]

David,
Interesting that the ears are on the newer model real PTO covers! With regards to the wiring harness, a fellow WFMer needed one and I sent it to him. Putting an late level rear PTO on an older model machine is more costly...as I recall the old wiring harness was listed around $125 on JDParts 3-4 years ago.

On the way home last night, I remembered you mentioned you will be installing a rear PTO soon. A couple of things worth mentioning:

1)The installation instructions Step11 state "Use a pry bar between the cover and frame (A) to carefully move the cover approximately 1.5mm (1/16-inch) to the right to align the top of the cover with the upper dowel pin." One member here did that and cracked the casting. He was able to repair it but to save yourself potential grief, he suggested that relieving the PTO brake spring pressure is a better approach. To do that, back out the three screws that secure the PTO brake cover. The PTO brake cover is a flat triangular shaped plate located at the upper rear right side of the transmission when looking from the rear. I would remove the screws part way (1/8-1/4") and then gently pry the cover open. Continue to back the screws out to relieve the remaining spring tension but don't totally relieve all the spring pressure in order to prevent the brake shoe from falling off the inboard end of the shaft. Although there should be no fluid inside, my PTO brake cover was RTV'd. There are three fairly stout concentric springs inside and it is those springs that produce the pressure required by the prying in the instructions. Once the rear PTO cover is installed, tighten the PTO brake screws.

2) Be careful to keep track of the orientation of the two cylindrical sleeve pieces you remove from the PTO solenoid and armature. As I recall, I didn't and soon found there were discrepancies in the instructions (for some reason I thought one or both of the sleeves was oriented incorrectly in the instructions..keep in mind, I have the earlier model instructions). I finally figured it out by reason but it took awhile...it just would have been better if I had paid very close attention when removing them rather than relying on the instructions to put them back together.

Good luck with your install....it is a fun install.

Tim

 

[jdmaninlouky]

More great info Tim ; Thanks !!

I am now trying to purchase a new harness , as I've resigned to the thought that I will not find a new (or used) one from any one but a dealer . Lots of sites say NLA , but a few show they have it - YIKE$!! - I would make my own if it weren't for trying to match those differing Weather-Pack connectors to factory , and then spending days trying to de-cypher the interface between the early and later styles .

. So I'm probably money ahead just getting a new one from dealer , if I can find one .

I will heed your advise on the install and hopefully not have any issues .Keeping my fingers crossed ! Thanks again Tim . (Dave)

 

[bobstillwagon]

I'm bringing this one back up as I'm having a similar issue with PTO seeming to slip when my 455 has been used a while. Mower cuts great when I first start but after 30 min. to 1 hour starts leaving a lot of grass still standing and doesn't seem to be throwing grass nearly as strongly and as far. Pulled the PTO off today hoping to find the oval seal distorted and found it looking OK. Think I will put the paper clip back in anyway though. I'm using the recommended John Deere Low Viscosity Hy-GARD and John Deere filter with 123 hours of operation since last change.
Anyone using synthetic hydraulic fluid? If so what brand, spec, etc. Thought is that synthetic fluid may hold viscosity better than the Hy-Gard?!
I plan to put the PTO back on (with the paper clip) and plug in a pressure gauge to see what is actually happening with the hydraulic pressure and also check temperature with infrared thermometer to see how pressure and temperature correlate.
So any ideas on what else I should check or replace while I've got it open?
Tim French, looks like you did not see any deformation a number of times when you removed the PTO from your machine so judging by that that could still be my problem?

 

[bobstillwagon]

See yesterday's post first for this to make sense.

Looked closer and my PTO (still off the tractor) has the little tabs to keep the oring in place just like the original cover. Guessing the paper clip won't fit now but will still try it to see if it does.

So back to not knowing what is causing my problem. Will reinstall the PTO and check pressure and temp as noted before.

 

[timf]

Bob,
Hmm..if you have the tabs to keep the oval O-ring from collapsing inward, I wouldn't think that you'd be leaking for the exact same reason. I agree though, your overall symptoms are the same as mine. In my case, the leak was miniscule while the fluid was cold...but as the fluid went from cold to warm and became thinner, I could see the pressure drop proportionately. It doesn't take much of a leak so be sure to replace both O-rings and carefully inspect the O-ring seats to insure there are no scratches or debris trapped in them. Yes, you are correct...I opened and closed the PTO a dozen or more times when I first got the problem....replaced the O-Rings every time. It wasn't until a few years passed living with the problem that the oval O-ring actually kept the warped set when I removed the rear PTO to see if the oval O-ring was my problem.

There is a possibility your PTO is leaking elsewhere. There is an O-ring on the PTO brake plunger..if is ies leaking you would see fluid when you crack the PTO brake cover (top, right rear side of the PTO when viewing from the rear) or the O-ring(s) on the PTO clutch pack assembly (I think you have to remove the PTO brake springs etc. to remove the PTO Clutch...this would be a last resort unless you are going for broke!). Fortunately for me, I didn't have to split the transmission to gain access to the other seals.

Bob, did this start after adding the rear PTO or having it open? From the little info that is out there regarding rear PTO pressure problems, they seem to work forever unless disturbed. In my case, I decided to add a rear PTO mid summer. It wasn't until winter that I added a good sized load with my snowblower that the problem surfaced...from then on I had the problem you describe whether mowing or blowing.

This is not an easy problem to troubleshoot as a leak anywhere in the system gives the same result....I feel your pain!

Tim

 

[bobstillwagon]

Tim: Thanks for the response! Got it back together and have run it an hour or so. It seems better but I'm still leaving a bit of grass standing when it is tall. Grass is tougher this time of year ... how's that for rationalizing?
Anyway, ran it about an hour and the temperature of the back of the differential case was 181 degrees and the hydraulic pressure at the connectors under the left foot area (I used the bottom connector closest to the tractor frame (which correlates to lower lever moved upward toward but not to the float position) started with about 1025 lbs of pressure and went down to just over 900 when heated up. So it appears that I'm down about 50 pounds from where I shimmed it to several years ago as I set it almost exactly at the 1066 max recommended and also that I lose about 100 pounds of pressure when it heats up moderately. Don't know if the pto cares about this variation or not. When PTO is engaged pressure drops momentarily then goes right back to the same number so that makes it appear that the pto doesn't being engaged has no effect on system pressure which I think is a good sign. I did really start noticing it after PTO installation in July 2011. Main thing I noticed before that was that heat had more of an effect when using the loader for several hours at a time when the hydraulic fluid was approaching 200 hours of use.
Not sure that I've ever thought the mower was perfect as far as leaving some grass standing as it always has if you move fast in higher grass so this might be as expected. It was better when I had the blade tip speed up but I've changed it back to the original spec now.

 

[bobstillwagon]

Oh, and one more thing Tim ... you mentioned your pressure had been dropping before your fix ... where did you check it? Note where I am checking in prior post so what I'm getting isn't PTO pressure (at least not directly).

Does anyone else get a poor cut with 4X5 with 60 deck when cutting thick grass 6 inches or more high. Mine gets better as I slow ground speed. And I do slow ground speed anyway when the grass gets thick enough to start slowing the engine rpm.

 

[timf]

Bob, my overall hydraulic system pressure never wavered. I have always had around 1200psi...the pressure that dropped was the reduced pressure the transmission lube oil reduction valve provides to the PTO. It's been awhile but I think the pressure is around 200 - 220psi normally but mine would slowly diminish to around 20-30lbs when the machine was warmed up. My machine would cut grass like no one's business when cold but as the machine warmed up the blades would almost come to a complete stop since the PTO brake wasn't being retracted nor was the PTO clutch fully engaged. I was using the port near the top on the right rear side of the transmission when viewed from the back. I believe it is the molded tube that comes from the base of the PTO solenoid. There are two ports in that area...I think either one will work. I had to use a 90 degree elbow in order to clear the frame.

Bob...while I had the low pressure....the blades would stop long before the engine would stall...now in high grass the engine rpm slows but the blades don't slip. I too find my 60" mower doesn't cut all that well if the grass is 6" or so high. I think the problem is the grass stays bent over instead of popping up. I have the high lift blades on mine...works great if the grass is 2-3" higher than cut height.

Hope this helps.
Tim

 

[bobstillwagon]

Thanks Tim. Makes me think I'm chasing a problem that doesn't have a solution then. I will find the ports in question and check the pressure at them after I find what I need to adapt my pressure gauge. If that pressure checks out, I'll quit chasing phantoms.
Sounds like anything over 300 lbs of system pressure won't change anything with the PTO anyway so I'm not sure upping my pressure would really help anything.
I'm sure it's just a matter of time before someone else is helped with the discussion! Thanks again for contributing your experiences for the rest of us to use!

 

[bearman61]

Gentlemen I have found that when cutting long thick (6" or more) grass with my 60" deck on my 455 it will leave some uncut grass. I believe that this is mostly caused by the mower simply being over loaded with. It can only process so much grass at once. There is only a limited amount of actual cutting edge and if this is overloaded the grass just gets pushed over. The only ways to overcome this are to go verrrrry slow to give the cutting edge a chance or cut at a higher height then re-cut at the desired finished height. Just my thoughts.

Barry