Do some hydrostatic transmissions come without a fan?

I picked up an old Craftsman 42 inch cut rider for FREE a couple years back. This is one of the old dark green ones from 1998 or so. It had been sitting in an overgrown yard when it was given to me. This is the type of deal where you have to come in with a chainsaw and a push mower just to get the thing out of its position. It had been sitting there for 3 years like this and surprisingly I had it running in about half an hour.

This became my rough cut brush cutting mower. It gets the hard use cutting brush and I just push right through it and run down small saplings which are then mowed over. I admit that I put this old thing through way more than it was ever meant to do but it keeps coming back for more.

Then a month or so ago it began to slow down dramatically if it was run more than a few minutes. I checked the transaxle fluid and it was full but black as coal. I also noticed that it didn't have a fan and looked like it never was intended to have one. It isn't like the fan was broken off. It looks to have never had one unless I am missing something....

I figured I would at least try changing the oil before considering it DOA. This is a Hydrogear unit and they suggested 15W50 or 20W50 oil so I went with Mobil 1 15W50 synthetic and changed it out. The old oil was black and had that broken down burned smell as well as that fine sheen that indicates metallic wear particles.

Anyway, I refilled and bled the unit with the 15W50 and the unit came back to life and can practically pop wheelies no matter how long the mower has been running. I have felt the transmission after hours of operation and you could probably cook an egg on it no problem. It is way too hot to touch for more than the time it takes to realize it is way too hot.

Any suggestion about the fan? I run this quite hard for hours on end at times and even though it is a rough old mower, it serves a good use as a brush cutter for me. I plan to change the fluid again at the end of this season as the oil I drained out the first time was quite nasty and figure another change cannot hurt.

I don't know that model personally, but I do know for a fact that you can break the fan blades off of the pumps if your not careful. Just by getting grass and twigs wrapped around them.

Chances are it had a fan at one time, but the blades have broken off. Just my .02.

You may want to investigate adding a fan by googling the model and trying to get a breakdown of the transmission. A picture should show you whether the fan was there originally or not.

Never seen one without a fan but then I have only been in the business for 4 years.
Are you sure it is a hydro box ?

How about a picture. A model number for you mower would be a thousand times better.

Just serviced a K66 with fan. That one has a pulley separate from the fan which rides on it. Is there "extra" threaded shaft above the pulley which would accept an e.g., 1" high fan? And regarding the blades this new Husky has blades which can be bend almost double to help seat a fan belt,. Do not know if heat/age embrittles these fans.

Never saw a hydrogear unit without a fan. Most bolt onto the pulley with three bolts, So depending what is going on, most of the fan may be gone.

I will get a picture of the unit tomorrow or so and hope the model is still visible. I seem to remember it being 917.something. I have lots of projects with work, the farm, and yes.... other mowers.

I don't remember seeing anything that looked like the broken hub of a fan but this might be a Frankenstein unit or something. I know that I swapped the motor soon after I got it going when the one it came with ate a valve and put a hole though the head and piston. I had to take a mower and chainsaw to cut down trees to get this mower out of its place when it was given to me so anything is possible....

I am positive it is a hydrostatic unit. The lever is continuously variable on the speeds and it had like 3.5 quarts of fluid in it when I changed it out. I don't think the geared units have this much. Plus you get the normal whine that is expected from hydro units.

I won't have a need for this for another month or so but want to figure out if it should have a fan by that time. If so, I think I will change the oil again before I use it again as it was quite hot when I put my hand on it. Even synthetics have their limits.

I changed the oil in the TT K46 after seeing the black sludge that came out of this one but it came out looking quite clean and it was obvious that I probably didn't need to change the oil but it had a working fan to keep it cool. Either way, it got a nice fill of new synthetic.

Well it looks like this unit is SUPPOSED to have a fan. Now I know why the fluid in this transmission came out as a black sludge when I changed it.

http://www.searspartsdirect.com/model-number/917271643/0247/1509200.html

Anyway, I am guessing this just bolts right on top of the drive pulley and that the previous owner removed it when it broke or something along those lines. I don't see the fan as a part number on the diagram but am assuming this is a common part for a lot of machines.

Since I have run this some time (at least 15-20 hours) without the fan since the fluid change, I plan to change the fluid once again when I get a fan an install it. As I said,, the temp of this transmission was smoking hot when I tried touching it after use. These were not just intermittent runs without the fan. It was run hard continuously for 4+ hours at a time so I consider this fluid compromised.