ZF ATF Filter cap issue

[Dougcole]

Hey All,

I just did my first fluid change on my ZF 63A transmissions.

There is cap on the stb side of the tranny that covers the filter. On top of the main cap is a second cap topped by a fitting that accepts a hex wrench.

My understanding of this cap is that the top fitting unscrews which releases the compression on the O ring around the main cap. I think the main cap is held into the housing of the tranny by compressing the O ring causing it to expand, sort of like the way a plug in a transom drain works. Neither the main cap or the tranny housing is threaded in any way.

When I tried to loosen the top cap the entire main cap popped out of the tranny housing and now I can't get it back in. The top cap will not turn, I'm not sure if it is corroded or just super torqued, or maybe it doesn't actually turn at all?

I have not put a ton of pressure on it as I don't want to break anything before I'm sure how it works.

Any body familiar with these things? Any idea how I can reinstall it? Pics are below, sorry they are upside down.

 

[RT Firefly]

Greetings,
Mr. D. Looks to me like it's exactly what you describe as a transom plug. Have you tried to unscrew the cap screw and THEN push it in the hole? Righty tighty, lefty loosy...
My BIL had ZF transmissions on a previous boat. During his delivery trip, unbeknownst to him, that cap popped off, fluid sprayed out and his transmission self destructed. No recourse from the dealer as the dealer denied checking and forgetting to tighten said cap. Make sure it's in tightly.

 

[Dougcole]

I can't budge the cap screw. I tourqued it pretty hard to cause the main cap to pop out of the housing and it didn't move at all. I have not tried putting the main cap in vise or anything like that yet. I want to be sure of what I am doing before I start going caveman.

 

[AusCan]

Doug, You are correct. The top cap doesn't turn at all. The top & bottom portion are one integral piece.

You should be able to just loosen the 6mm allen head bolt allowing the cone portion to back off and the o-ring to decrease in size.

When re-installing, tighten to: minimum 4; maximum 6 ft/lbs.

Here is an owners manual if you need one. http://www.harbormarine.net/pdf/zf-repair-manual-63a-80a-85a.pdf

 

[Dougcole]

Thanks AusCan,

That 6MM allen bolt won't move at all, so what do you think of clamping the cone portion and applying more pressure?

 

[twistedtree]

Yes, clamp it in a vice, but be careful. Also, perhaps soak it in PBBlaster for a while

 

[Dougcole]

It's soaking right now, actually. I haven't made any headway. I tried clamping to the little tab that says "ATF" on it, and put some pressure on the hex nut. The tab broke off.

It's hard to clamp a cone in a vise.

Whoever put it in before tightened it to a lot more than 6lbs, I can tell you that.

I'm starting to think I'm going to be ordering a new cap.

 

[Dougcole]

Got it. Put it in my neighbors bigger/better bench vise and used a 4' long persuader pipe on the allen wrench. Made a loud crack as it broke loose, man it was tight.

Thanks for the help guys.