Filter locations by model

ZF63A ZF63IV work through the weekend

Where to find it, by model

• 71/72 series (1017/1018): pull the return plug on a cast-iron unit and you may find a spring and a washer, a little screen on the newer ones, or nothing at all. If you find a spring and washer, throw them away; they don't do anything. The magnet down in the bottom does the actual work of catching metal. Some early units had a tube in place of a screen; leave it alone. Don't count on any of it to save the transmission.
• 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.

Spring and washer

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. On a 5000 or Liberty, a clogged suction screen under the pump cover is one of the factory's own listed reasons a unit shows no forward or reverse at all, right alongside a broken prop or a blocked cooler line.

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 ($84.95) 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.

Related reading: Velvet Drive transmission fluid and finding and fixing transmission leaks.