Snowblower Hydrostatic Drive - oil level?

[aesmith]

Hi,

I'm not sure if this is the right section. Just wondering if anyone has any knowledge of the sorts of hydrostatic drives as fitted to lawnmowers and in my case to a snowblower. The machine is a Stiga 1171HST, as far as I can see this is the same OEM as Murray in the US, it's an American made machine. I believe he drive is made by Hydro Gear but I don't know the model number.

My issue is oil level, whether the main casing is supposed to be completely full, whether there should (when cold) also be some in the expansion tank, or whether there's a predetermined level that I should fill to.

What I have found on examining it is a fill plug on the side. Then at the top there's a plastic expansion tank. Going into the expansion tank from the highest point is a thin tube with a heavy valve or filter in the end, somewhat like the fuel line of a chainsaw. In turn the expansion tank has a tiny hole that I presume is an air vent, with a cap over it. It look like the intention is that oil would be sucked back in when the unit cools down and the oil volume reduces.

My thought, but this is only a guess, is that the main housing should probably be completely full, otherwise it wouldn't need the expansion tank. And maybe the expansion tank should, when cold, contain just a little oil.

Any ideas?

Thanks, Tony S

 

[Burnerman]

Keep your expansion tank one third full of oil.....the level shouldn't vary at all.
I think the level plug is actually a bleed plug - these transmissions are bloody awkward to fill otherwise.
Some transmissions have two drain plugs but if you are going to tamper then do some research first as they are hideously expensive to replace.....I was recommended fully synthetic 5W/30 for my Husqvarna Rider machine but I wouldn't know of this is universal.
I've only limited experience with these things.....in particular the Tuff Torq K series transmissions, and when I drained one it wouldn't refill. Panic time!
John

 

[aesmith]

Cheers. This transmission's been trouble almost from new, keeps losing oil and nobody neither Stiga nor the dealer could say where or why it's coming out. So if in doubt, like now when I suspected an abnormal noise, I wanted to check it out. A bit of a pain as the blower needs to be upturned to get the drive out, meaning draining oil and fuel. There's a specific bleed procedure to follow once it's back together. Our old ride-on had Tuff Talk K46, they seem to be more open with service info than Hydro Gear. And the machine manufacture useless of course, as far as they're concerned the drive is sealed for life with no service possible.