comments about your ZF5 failure

[IDIoit]

you may be the victim of galvanic corrosion. take a short punch and hammer and place the punch at the center of the plug. rap firmly with hammer. try again. if not, hit the alu with a torch.
good luck!

everyone has their own way of doing things, this was discussed about 2 weeks ago also.
some say heat the bolt, some say heat the aluminum,
i would do what towcat said, with my own little twist.
i heat the aluminum then spray it with PB then heat up again and try again with the aluminum hot.
DO NOT GET IT SUPER HOT!
may the force be with you.

 

[direwulf23]

Transmission manufacturers caution strongly against coasting with the transmission out of gear. As said, the input shaft keeps turning.

 

[david85]

Interesting. I didn't realize the ZF-5 had a pump. I'll probably never own one but its still good to know.

 

[IDIoit]

i could be wrong, but i dont think they do have a pump.
i thought the gears inertia picked up the fluid as it was driven.
hence towing it in neutral does not lube the internals??

 

[The Warden]

If your towing put the tc in neutral right? then the zf5 is not spinning correct? I guess with 2wd thats not an option.

I've heard that as well, but I'm not 100% sure you're safe with the transfer case in neutral...any chance of someone who knows the ZF better confirming that that is or isn't the case? Thank you

CERTAINLY, that's not an option on a 2WD truck, as towcat said...on a 2WD truck, you absolutely need to either disconnect the rear driveshaft or get the rear wheels off the ground.

 

[LCAM-01XA]

I've heard that as well, but I'm not 100% sure you're safe with the transfer case in neutral...any chance of someone who knows the ZF better confirming that that is or isn't the case? Thank you

You don't just neutral-out the t-case, you also need to place the transmission in gear (any gear) to prevent the output shaft from turning. NP435s have the exact same quirk, and that is the solution to it. Of course you really need to be sure the transfer case oil pump is driven by the output shaft, and not the input one instead (which will be stopped due to it being locked to the transmission). The BW1356 is one such t-case (have one split, just checked it), as long as driveshaft is spinning it will not starve for oil. On the other hand, you really want to avoid running the transmission in gear with the t-case in neutral and parking brake on, as that means the planetaries are turning but receive no pressurized lube flow due to the stopped output shaft (and by extension oil pump).

 

[G. Mann]

I thought I had a good set of pictures and overhaul manual for the ZF5 transmission, and I don't recall anywhere in that seeing a "transmission oil pump" .... Edumacate me please...

Is there one, and what does it look like... "Show me" if you would... Picture would be nice.

 

[towcat]

Interesting. I didn't realize the ZF-5 had a pump. I'll probably never own one but its still good to know.

you're right. it does not have a pump. BUT. It uses the pumping or climbing action of the oil from the input shaft gear to start lubricating the input shaft bearing by spinning the countershaft. also, the main bearing supporting the main gear cluster assy is nestled inside the input shaft gear. oiling is then distributed throughout the rest of the gear cluster.

 

[G. Mann]

Thanks for clearing that up. After reading the previous posts I thought I had missed something when I looked at the parts manual and overhaul manual, cause I saw no oil pump as a separate item.

The gears pump oil.. starting with the input shaft... not the tail shaft.. got it now...