Creeping neutral and selector valve problems
What Chris sees on the bench
- A little creep in neutral on old transmissions that stops as long as you hold it. It doesn't take much to stop it. Chris puts that down to the bushing in the case, and calls it normal for these old units.
- Scratches on the selector valve on a transmission that had no pressure.
- Pressure that stayed the same in reverse, neutral and forward on the test stand, which told Chris the problem was probably the selector valve.
- A plunger rusted in on the bottom. Sometimes if you get water in a transmission, that happens, and it won't give you the pressure you need.
Fix
If the creep is light, stops when you hold it, and there's no abnormal noise in reverse, neutral or forward, that's normal for an old case. If pressure is missing or reads the same in every position, pull the selector valve and check it for scratches, and check the plunger for rust. When you reinstall the valve, line it up with the bolt on the bottom. That gives you neutral, so the ball lines right up and you don't have to fiddle with it.
Two related things that can look like a neutral problem
A flattened filter cover O-ring on ZF units. The O-ring should be round. When it goes flat, it doesn't make good contact with the housing, air gets sucked in, the pump neutrals out, and you're dead in the water. Replace the filter and O-ring yearly, or at least every two years.
A melted baffle in an overheated cast-iron Velvet Drive. If you ever have an overheated cast-iron transmission, disassemble it, because you're going to find that baffle melted.
When to call
If pressure reads the same in every gear or you've got no pressure, call (804) 333-3677, Monday through Friday 9 to 3 Eastern, or email sales@halemarine.com.
Related reading: low transmission pressure and water in your transmission fluid.