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Hydro-Gear 650: bypass not working

3489 Views 5 Replies 2 Participants Last post by  Mark / Ohio
I just rebuilt my 650--replaced all the gears and seals.
I have the factory service manual, which helped alot, but it doesn't show anything about the bypass valve..
I seem to have full power in forward and reverse.
However, the bypass valve isn't working at all.
Any ideas? I can live without it, but it would be nice to have working.

I want to have a clear idea of what could be wrong before I open it up again.
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Welcome to the forum Rick. Does the valve move but just no bypass?

What is your Craftsman model number? Also Looks like there might be several versions of the 650?

Hydro-Gear Parts online catalog,

I've never had one of them opened up but maybe I can dig around on the net and see if I can find anything. :)
Hydro-Gear 650 bypass failing

Craftsman Mode# 917.258591

Bypass moves easily, just doesn't do anything.
The service manual that I have covers models 550 and 750.
The 650 seems to be identical to the 750

Appreciate the help.
I see what you mean about the lack of detail on the bypass valve assembly. :(

Here's the exploded view I'm looking at which is probably the same as yours:

Likely a problem in the area of where (25) actuator moves (30) the bypass plate. But what is the $64,000 question. :confused:

Any chance of arm (35) just not being in the right position or slipping on the actuator shaft (25)?

I'm trying to find an external problem so you don't have to split the case again. ;)

No other thoughts I'm afraid. I have not found any postings so far of anyone having a similar problem after putting one back together other then one guy mentioned the bypass plate falling out and he could not find where to put it back even by the service manual on a different model. :rolleyes:
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It moves freely and completely in both directions. Its very solid to the shaft.
Luckily I have two units. The second unit, which was a rebuilt, lasted two years. Now it loses most of its power when warmed up. I suspect the pump needs replacing.
I don't have time at the moment to open it--just started a new job, but should in a week or two.
This model is very light duty. I live on a hill, and also have a utility wagon I pull. Now I make sure its never more than half full. The weighted tires also increase the load.
Next time I buy a tractor/mower, I'll look more at the tranny than the horsepower.
....Next time I buy a tractor/mower, I'll look more at the tranny than the horsepower.
Yeah, that's one area all the tractor manufactures seem to go cheap anymore unless you pay for the higher dollar commercial grade models. I wish my Deere had one of the more stout models of Tuff-Torq in it. It's about half the weight and strength of the old Peerless gear drive that was in my early 70's Jacobsen 8 hp. rider.
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