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tommyg

Interpreting Hydro pressure readings

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Wow, that's pretty bad.

Good news is you found the source of the problem. The bad news is the strainer is no longer available.

I think your options are to either fabricate something to take it's place, or keep your eye on ebay hoping to see one.

Just my 2c worth.

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It will be interesting to see the valve plate of the originla motor.

There is a recently disassembled rearend on ebay. If you contact the seller he may have the screen out of it.

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When you do get a pic of the damage done to the valve plate can you also measure the thickness of the valve plate at an unworn position. There are two reasons: firstly it will help me to narrow down the motor valve plate used in these (as far as I can tell there were three different 15 series motor valve plates), the second reason is that I've found two references that indicate that you can take up to 10 thou from the surface when lapping assuming it hasn't already been done before.

As Coldone has already mentioned it's a real drawback of the design that the fine filtering is carried out in the return circuit rather than when the oil is being drawn up from the transaxle reservoir hence the need for the strainer. The standard 15 series spec calls for the filter to be in the flow to the charge pump rather than the return but for convenience in this application sadly it's in the return. I suspect the major reason is that, for it to be in the flow, the filter has to be mounted below the level of the reservoir to ensure it naturally fills with oil and the charge pump can prime but there isn't the ground clearance in the smaller tractors to achieve this. I think at some point we're going to have to find a strainer that can be adapted to fit or get some replacements made up.

A second limitation of the system is that it is an 'open vented' design via the dipstick cap which is the reason the oil and filter have to be changed every 100 hours. I guess it's therefore inevitable that as air in the tranny case expands and contracts some microscopic airborne particles are likely to get drawn in each time.

Picking up on the point about the number of 'sloping cuts' in valve plates, yes, pump plates have just two, and motor plates four because of the need to rotate in either direction but there are two different pump plates (for left hand and right hand rotation). In all there are a total of four different 15 series pump valve plates and three different motor valve plates based on part numbers. I doubt that a valve plate would have been designed specifically for the WH application but we're not yet at a point of being able to buy up the first NOS plate that appears for sale.

Sorry for another ramble - my head is full of 'Sundstrand' at the moment having spent hours looking through exploded diagrams etc. :scratchead:

Andy

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I think its the thin plate. When i finished lapping mine the thickness was 0.147. I didnt think to measure before lapping.

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That dimension also tends to make me think that it's the 'thin' plate as the recommended thickness range with respect to lapping is .151 - .161 ( I guess you may have taken just a tiny bit more off than is ideal).

It's still a bit of a big if...... but if we're correct in this assumption then the Sundstrand part reference for the motor valve plate is 3102687 (from the exploded diagrams I have) or more precisely 21-3102687 according to other sources. Google results bring up various lawn care parts suppliers in respect to parts for Sundstrands on various different tractor manufacturers products. Interestingly, as an OEM part there's a considerable difference in prices charged. I think I'm right in saying that the plate is still available as a Toro part (94-1805) from some stockists but if it is the same as 21-3102687 then it is available rather cheaper as an OEM part for other brands.

The only worry I have in declaring this is that it is very much still a big if and there was a third valve plate of unkown thickness used in Series 15 'tandem' configuration. I'm kind of 80% leaning towards it being the 21-3102687 though particularly given the dimension you took.

Andy

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Andy,

i tried posting pics of the 15 plate and the WH plate here but I cant for some reason. I sent them to you in email. There is a difference in the mounting holes for the alignment pins, but I think the center (big) hole is physically smaller on the 15 plate. Also I can only see one side (brass) in the pics so I cant compare the back side.

Well we will find out in a week or two what the deal is. I found a 15 series plate for a good price and I stumbled upon a WH motor at a good price. They will be here next week probably, but I will be on vacation. I plan on pulling the motor apart and comparing the plates.

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Well, you guys, I started this post back in May. Had no idea this process would be dragged out this long. After getting a replacement screen from jdog, I set to work replacing the seals. The transmission had to come out and apart since the damaged filter screen left shrapnel inside the casing. From that point, things kind of went south. But I'm happy to report that the final chapter on this post may have been written! I've got lots of updates and photos that I'll try and post tomorrow or the next day. Just wanted to post this to keep you on the edg of your seats! :-)

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Looking forward to it Tom. Thanks for sharing your hard learned lessons with us all!

j

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Hydro Pressure Readings... the final chapter!

OK, here it is. After a month of frustrating setbacks that included having to replace a chewed up filter screen, destroying the hubs just to remove them, damaging both axle snap ring groves, watching all the little needles fall out of one of the needle bearing fora transmission gear and completely destroying an axle bearing because I didn't remove paint from the replacement axle, I finally got to work putting it all back together after my hydro motor overhaul. Here's how it went...

The replacement screen from jdog had issues with the end pieces. While they fit snugly over the end, they didn't stay put. I'm guessing this was the reason for the demise of the original. James suggested JB Weld, which was a good choice. Withstands 500 deg temps as well as oil. I made sure the JB Weld was worked into the folds of the filter element to make sure it held tight.

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Here's a pic of the bearing I ended up replacing. The needles just started falling out. I'm sure I lost at least one of them. I figured I might was well just replace it rather than take any chances.

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Here's the one axle bearing I had to replace. As I slid the replacement axle in, it started to get tight. Rather than try and force it, I backed it out. But it was too late. The accumulation of paint on the outside of the axle destroyed the bearing. I had just replaced both of the seals as well. So, I had to destroy a brand new seal in order to drive the bearing out from the inside. I was not a happy camper about this. Almost lost my religion that evening. Note to self... Make sure every last bit of gunk is off that axle before sending it through the bearing. If you don't, you'll live to regret it.

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Here are the two halves of the tranny just before I started reassembling.

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The newly overhauled motor ready to be installed

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Before I put the replacement hubs on (also from jdog) I made sure they fit on smoothly and would not freeze up again by smearing it with anti-seize compound. Did this for the keyway, too. It also acted as a lubricant to help them slide on even easier.

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Everything assembled except for the last hub.

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Since I had it this far, it made sense just to put a coat of paint on the project. So I made sure it was cleaned up, and sprayed it with Rustoleum Regal Red. Didn't quite match perfectly, but that's the best I could do. Used a hardener to make it dry faster and keeps it looking glossy.

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Transmission back in place on the tractor.

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Finally, after everything got hooked up, it was the moment of truth. I started the engine with everything raised up off the ground and made sure the wheels turned. They did, much to my excitement. (Hey, little victories here, OK?! :eusa-clap: ) After the first test, I throttled it up to about half way. The pressure was reading about 100 psi give or take. I'm not sure the accuracy of the gauge as I could tap it and make it read 120 psi and tap it again and make it read 80 psi. So I guess I'll just use the average of 100 psi. Does that sound about right?

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The real test, however, came when I got the tires on and backed it out of the garage. I throttled it up, pushed the lever forward and almost popped a wheelie! This was no fluke. This was a 100% difference from what I was used to. While I couldn't test it that night, I couldn't wait to get home from work to cut the back yard. The result was nothing short of amazing! That tractor had so much power to those wheels I could not believe it was the same tractor. The pressure stayed pretty constant, dropped a little as it heated up, but no more than 20 psi. That doesn't sound too significant to me. Still, I would like to see that pressure over the 100 psi mark all the time. But I can't complain. The transmission oil temp never got into the warning zone. about 175 deg F.

SOOOO, I have to say that the motor overhaul was a resounding success! Thanks for all the help and encouragement! I'm thinking that this winter, I might do the same to the hydro pump, just to make sure everything is working as good as it can work. I am thrilled with the performance of my D180 and my new ability to tackle a challenging project! I was definitely worth the effort!!!

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Excellent write up and photos Tom and I'm soo pleased that youv'e got there.

Thinking back I can't help wondering if that implement valve had been deliberately jammed by the PO in an attempt to raise the charge pressure and get the tractor to go on a little longer but I guess we'll never know.

Loved the strengthening repair to the filter. I'm not sure if we have a similar product to JB Weld made over here or how it differs from the various standard epoxy products but I discovered that it is available in the UK - a chance discovery in that I noticed a pack on the counter at my local motor factors. It wasn't a normal stock item and they'd got it in for another customer but they've now ordered several packs in to make it a stock item so I'm going to pick up a couple of packs.

Andy

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I love a Happy ending! Great write up and great job getting it going again.

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Excellent write up and photos Tom and I'm soo pleased that youv'e got there.

Thinking back I can't help wondering if that implement valve had been deliberately jammed by the PO in an attempt to raise the charge pressure and get the tractor to go on a little longer but I guess we'll never know.

Loved the strengthening repair to the filter. I'm not sure if we have a similar product to JB Weld made over here or how it differs from the various standard epoxy products but I discovered that it is available in the UK - a chance discovery in that I noticed a pack on the counter at my local motor factors. It wasn't a normal stock item and they'd got it in for another customer but they've now ordered several packs in to make it a stock item so I'm going to pick up a couple of packs.

Andy

Andy, I think that if it were deliberately jammed, there would have been a more deliberate process in jamming it. But like you said, we'll never know. JB Weld is as standard here as duct tape. I'd be happy to pick up a pack or two and ship it over for all your input.

Here are my final thoughts, though... Am I good with the pressure readings that I have? It still seems a bit on the low side to me. I"m not certain about the accuracy of the gauge. I really could not detect any drop in performance as it warmed up. Should I be concerned that taking the implement valve to the ends of the travel only nets me about 450 psi and not the 550-750 that the manual says? Just wondering.

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Amazing writeup Tom. The pictures are great!

I like the way you jbwelded the filter together without getting it all over the place. Looks very factory. Myself, I usually end up getting it all over the place.

I am very pleased to hear that all the hard work and effort paid off. I know what it's like attempting a repair like that and not knowing if you are wind up with a pile of scrap metal or a working tractor.

Andy, JBWeld is pretty ubiquitous here. Just like Tom said, as standard as duct tape. I even used it recently to fill in pitting on part of my deck. It's basically a two part epoxy. I'm sure you are going to find a million and one uses for it.

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On a trivial note they got the JB Weld in the next day so it's obviously stocked by their wholesalers. Haven't had anything to try it on yet to see how it differs from the range of two pack epoxy products that are more widely stocked but I'll let you know.

Here are my final thoughts, though... Am I good with the pressure readings that I have? It still seems a bit on the low side to me. I"m not certain about the accuracy of the gauge. I really could not detect any drop in performance as it warmed up. Should I be concerned that taking the implement valve to the ends of the travel only nets me about 450 psi and not the 550-750 that the manual says? Just wondering.

I'm sure the others will chip in on this Tom but I'm kind of thinking that we only have the manual as a guide to pressure readings and its only recently that guys on the forum have actually been taking readings to investigate issues with the transmission. It hasn't become a precise science yet. The other thing is that if the filter shrapnel scored the motor valve plate then there's more than likely some damage that's been done to the valve plate in the pump though clearly not enough to stop you from pulling wheelies!. Manuals on hydros tend to point to the fact that both will need to be overhauled - as you said, a job for the winter. For now enjoy enjoy some seat time :) .

Andy

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I disconnected the pressure gauge. I'm not going to dwell on it. Without the gauge, I would never know if there was an issue by the way it's performing. Thanks to Paul for letting me borrow it.

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Tom, My D 200 does good but after awhile the hydro gets hot and becomes weak. It takes a little over an hour tomow my yard and by the end of that the hydro is still moving but not as strong. The temp never gets to the yellow section of the temp gauge but its right at it (190F i guess) I plan on pulling the pump this winter.

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My temp might have climbed a bit higher if I ran it longer. I cut the back yard (admittedly quickly) in about 35 min. Can't say the temp settled out at 175. But I can say that it would be a stretch to say there was any decrease in performance. If there was, it was ever so slight. Regardless, I am going to do the same this winter. I have a second pump (the original) in my basement that I can work on in my leisure, then swap it out once I do the overhaul without too much down time.

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Epilogue... Is it possible for your D to work too well? I've cut my grass cutting time down by a third, which means I'm spending less time in the seat. The grass just won't grow fast enough for me. Might ask the neighbor if she minds if I cut hers. Have to be careful not to spin the tires at every turn. Redeveloping my touch on the forward and reverse lever slowly. :) Not sure I'm even gonna mess with the charge pump this winter!

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Epilogue... Is it possible for your D to work too well? I've cut my grass cutting time down by a third, which means I'm spending less time in the seat. The grass just won't grow fast enough for me. Might ask the neighbor if she minds if I cut hers. Have to be careful not to spin the tires at every turn. Redeveloping my touch on the forward and reverse lever slowly. :)Not sure I'm even gonna mess with the charge pump this winter!

If it ain't broke.....

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