Filter locations by model

By Chris, Hale Marine · 40+ years rebuilding Velvet Drive and ZF transmissions

Short answer: Filter service depends on the model: the ZF63IV has a drain plug and the ZF63A doesn't (pull the filter to drain); ZF 45-85 filter covers must sit flush; 5000-series filters sit under the pressure regulator cover.

ZF63A ZF63IV work through the weekend

Where to find it, by model

ZF63A: no drain plug port. To drain, don't use the dipstick hole. Pull the filter out; that opening goes right to the very bottom of the sump.
ZF63IV: ZF put a drain plug port on the V-drive version.
ZF 45 through 85: filter sits under a cover; when you put the cover back, make sure the body sits flush with the housing. If it's not flush, most times it'll suck air and neutral the transmission out. The transmission will just stop after it heats up.
5000 series: take the cover off and you'll find the spring for the pressure regulator, with the filter or screen down below it. That plate is under a lot of pressure, so be careful. Start with the two top bolts and loosen them a couple of turns at a time until the top pops.
ZF63 filters: buy the newer-style filter. It has a shorter bowl, and on the A models, the V models, pretty much all of them, the case needs that shorter bowl for clearance.

What causes filter-related problems

On ZF units, watch the O-ring on the filter cover. It 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.

And don't count on a filter to save you from sludge. On a cast-iron Velvet Drive, Chris found that whether it has a filter or not doesn't make a big difference: the sludge goes right through that little screen without plugging it up.

Fix and prevention

On ZF units, replace the filter and O-ring yearly, or at least every two years. On the ZF63A, get comfortable pulling the filter to drain since there's no drain plug to rely on. When servicing a 5000-series filter cover, take your time on those top bolts. We carry the ZF filter kit (~~$62.49~~ $42.00) for ZF63 through ZF85 and Hurth HSW450-800, and the 5000-series filter screen ($90.00).

When to call

If a transmission stops after it heats up, or you're not sure how to drain your model, call (804) 333-3677, Monday through Friday 9 to 3 Eastern, or email sales@halemarine.com.