Help with fluid change on Spicer hydro-tranny

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  #1  
Old 05-01-10, 08:58 AM
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Help with fluid change on Spicer hydro-tranny

I have a 46" 18hp Murray Ultra with a Spicer 93264 transaxle I bought several years ago 11th hand and without a manual. It's been sitting a few years and I've decided to rehabilitate it and start mowing with it again. The fan on the hydrostatic pump was busted so I pulled the transaxle to replace it and I figure to replace the fluids while it's out. Right now I have three principle concerns.
1) How do I drain the fluid? Through either of the plugs (pictured below) or turn it upside-down and drain it out the reservoir?
2) What do I replace the fluid with?
3) How much replacement fluid does it take? If the amount is unknown, can I just top it off and spin the pump by hand, then re-check the level? This has to be done before reinstalling the tranny because the reservoir is absolutely inaccessible once it's put back together.



The mower model is 46902X106A, S/N 95060 018xxx.
The motor model is 422707, Type 1264 01, Code 950 1195a.
The transaxle is a Spicer 93264 / Dana 4900-3.

The reason this mower went into storage was that it was so slow, I could finish faster my 40" rider instead (and the 40-incher by no means is a speed demon). It didn't seem to get progressively slower, it was slow right out of the gate. And it was noticeably slower uphill than down.

It also had very low torque. If I wanted to climb up over a 1" rise onto a paved driveway or sidewalk, I had to take a running start and build up a head of steam first. The compression is decent and the RPMs sound okay so I always figured the hydrostatic drive was weak.

It also had the habit of burning drive belts about every 15-20 hours of operation. While it was parked, I started thinking a weak hyrdo shouldn't have the power to burn the drive belt, which set me to wondering if the problem might have been too little tension on the drive belt. So I bought a new belt and both jockey pulleys and tension springs. I crawled under it to replace the drivetrain and that was when I remembered the fan was bladeless and decided to pull the transaxle to replace it.

When I got it out, I found that the fins on top of the pump were full of crud. Not mud but dry earth and grass clippings that definitely would have interfered with the cooling. The fluid level is okay but the fluid is jet black and thin.

Long story short, am I thinking right that a burned belt probably means too little tension? With no fan and the cooling fins clogged, it's a no-brainer that my hydrostatic drive was overheating. Could this have happened so soon after starting the mower that it would have felt low-powered within seconds? Is that maybe why I wasn't noticing any decay in speed, because it got as bad as it would get within the first few feet?

BTW, my local mower shop tells me the cooling fan is no longer available so I'm fabricating one out of HVAC aluminum duct sheeting. I'll post the results when it's finished.
 
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  #2  
Old 05-02-10, 12:30 AM
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If it was going through belts that fast, there was definitely a belt issue of some sort. If the pulleys are all in good shape then I'd say the tension was the reason for the belt failure. If the belt was slipping, it would make a big difference in performance. I suspect that is the reason for your problem. If you were to drain and refill the oil, do it as you described. I don't know how much it takes. If I were to put fluid in it, it would be 20w-50 oil.
 
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Old 05-02-10, 07:18 AM
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What were you using for belts? Standard automotive belts will not stand up to the stresses that outdoor power equipment puts on them. I would also use synthetic oil in the tranny.
 
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Old 05-02-10, 07:36 AM
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I've always used Murray-brand OEM replacement belts. The pulleys felt free enough when I removed them but I already bought new ones (also OEM) so I'll replace them anyway. I also have new springs.

I didn't have the foresight to move the thing undercover before the floods started two days ago so I'm waiting for the weather to break before I can put it back together. I reckon I'll replace the fluid with Mobil 1 20-50.

Anybody know why this thing has two drain plugs? Could there be separate fluid supplies? There's only one reservoir.

Is spinning the pulley on the pump by hand likely to remove the air in the system enough that I can get a decent fluid level in it?
 
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Old 05-02-10, 10:57 AM
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One reservoir/sump area holds gear oil for the differential, the other holds the oil for the pump. You can remove a lot of air by spinning it by hand, or you could use a drill to really purge it before installation.
 
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