Changing ZF80A HSW 800 A2 filter – More Art than Science?

[Paul]

Just replaced the stbd turbo drain line on my 1999 Cummins 6BTA 5.9 M3 330 HP, and while running the engine to check for leaks noticed that I had ATF leaking out from the transmission’s filter cap.  No leaks on the drain line – yippee for that.

Quick check of the repair/parts manual had me grab my 6mm Allen wrench and get into a boat yoga position to tighten the cap.  That didn’t help (it was already ‘closed to the stop’), so I’m guessing I have a software problem. 

Figured I might as well change the filter when I replace the software … but I’m afraid I don’t have the artful skill to ‘pop’ the cap up.  Turned the cap lefty loosey until the cap’s ‘tab’ contacted the housing body, and tried to get a little ‘lift’ from a screw driver in the tiny cap under the cap, but no joy. What’s the magic touch I need to pop the cap so I can get down to the O-Rings and filter?  Those parts are on hand, hoping to not have to replace the cap itself (based on the $$ I saw in SBMar’s parts bin).<br /><br />Here’s a pic (didn’t want to load the vid) of the ATF oozing out from under the closed cap.  

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[Paul]

Just needed a bit more muscle …

Was able to disassemble the filter today … just got a better angle on the screw and things came apart easily.  Thanks for the info – another routine maintenance item I can add to my “don’t have to pay for this to be done” list.

[Paul]

Thanks Tony & Graeme

Weird – yesterday I did a YouTube search with key words ZF/transmission/filter/replace and didn’t see that one.  So it seems my ‘real’ problem is simply that my screw is probably just in need of a good soaking with Kroil so I can get it loose.<br /><br />As always, great community with super suggestions.  Will let you know how things go.

[Tony Athens]

Changing a Hurth-ZF ATF type oil filter

Does this help?

 

https://www.youtube.com/watch?v=LjfpeqMROwg  

Oil Filter change on a ZF/Hurth ATF type transmission

 

 

 

[Paul]

So maybe more science (at least torque) than art

To get it off you need to continue unscrewing after the tab contacts the housing. 

Ahhh, so the screw is one of those ‘compression driver’ type of thing that ‘pushes’ the rim of the cap outward when it screws in, and ‘releases’ some of that outward pushing when it is unscrewed … I guess?  Luckily the area really isn’t too inaccessible, just a bit of a tight squeeze for an old fat guy like me.<br /><br />Sounds like you have pressure in the transmission and/or it is overfilled with ATF.   

There is usually a ‘hiss’ when I unscrew the dip stick, but my level has always been between the lines … it’s low now after the leak, I’ll refill it after replacing the filter & software.<br /><br />Thanks for the info … will probably have to soak the screw for a bit before I go after it again.

[Graeme Walker]

To get it off you need to continue unscrewing after the tab contacts the housing.  a stupid design if you ask me, especially since it is likely always in an inaccessible area.  You should be able to lift the entire unit out but not via the cap.  The entire unit can be disassembled but don’t bother.  The filter is attached via snapping onto the lower o-ring and the whole unit needs to be reinstalled as a unit.  Reinstalling you just turn the Allen key the other direction, doesn’t feel like it’s a positive engagement and never looks like it’s properly installed.

Sounds like you have pressure in the transmission and/or it is overfilled with ATF.   See Tony’s tips on how to measure fluid level depending on the version of dipstick.  I’ve never had mine leak there and always change fluid at 200 hrs or 1 year including new filter.

Good luck!

[Author]

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