Thread: ZF 4HP22 Gurus. Advice needed.

Did you fill it correctly..by changing gears etc to ensure the oil is at the correct level?

If it works okay I would be inclined to leave it alone BUT if it has been driven without oil damage to the clutch facings could well occur. Pulling them down is not that hard..just take note of assembly order and get a manual. Clutch facings and steels need to be inspected and measured for wear. Dissambling the pistons is more difficult tho and if you go that far you really need a rebuild kit.

Hard to say where damage is most likely but I suspect the filter sound is likely to be the torque converter not being fully charged.

Inner bearings eg in the clutch packs could also be damaged wirhout oil as they are quite fragile.

Was there much metal or other debris in the pan? If so then that usually means a rebuild is needed.

Again hard to say but shifting problems without slipping may well be related to the valve body being choked with debris.

Good luck...they are not cheap to get rebuilt in Aus that's for sure 😐

I would be trying the level again at first. We have had countless towed in with burst oil lines etc, none have suffered any I'll effects .

nice thing about the 4hp...

if it dumps the oil in a hurry all drive stops pretty much instantly when the line pressure fails.

no line pressure no clutch pressure no clutch pressure no wear.

spin the engine too long and the lube thats left will go from the front end and you'll take out the pump and first bearing set.

roll it for miles and you'll take out the back sprag and bearing.


now running it low on oil for ages... is a different story.

thanks for the input guys. after the leak was fixed, the box was filled as per spec. filled, turned on, filled until overflowing, then i think i ran through gears etc and topped up again. pretty sure i did it all correctly as i've done it several times before.
filter appeared clear. there was no debris in sump at all.
when road tested on "farm road " all was ok. my impression was that it was taking longer to get up to speed. i could be wrong on that as i have a very light foot. i have no idea what previous owner did when the "...." hit the fan.
since the road test i have fitted a rebuilt autobox from my parts car into the project car. can get rebuild kit from ashcroft's easily enough or outlets in u.s.a. kits with steels seem to be rare. just for practice i bought a rebuilt 4hp from a bmw for pennies . i'll strip that first. no doubt the parts will be different. but good practice.
again thanks for the input guys. -)

so i decided to partially strip it to get an idea of its internal condition. i would never be able to sell it on in good faith if i didn't check it out.
made a workbench out of an old double sink so that all liquids could drain into container :-)
unbolted the bell housing and pump. popped open the "A " pack ? first one after the pump. the friction plate still had the part nos visible. it is .047" which is virtually new spec. plenty of meat left on the plate. the steel, while showing discolouration, appears o.k. i've got the same sort of discolouration on the camshaft in my td5 . it was .071" again in spec. there are a couple of very, very, very tiny scratches around the steel. nothing with a ridge !! surface only.
pulled the sump and removed the filter. as you can see its black. wiped it with my finger in the pic. overdue for a service. internal mesh looks clean ( as far as i can tell ).
no big bits of metal around magnet, just black grease like stuff with very fine metal powder mixed in with it. again i've seen this stuff before.

so is the "a" pack an indicator of the overall condition of the box ????

while the box is out i will change the front ( torq. conv. ) / back shaft seals. silly not to. gofer :-)

IMG_20190907_155808.jpgIMG_20190907_155922.jpgIMG_20190907_155953.jpg

I tecently dismantled 2 re4 patrol autos and yes the condition of the first clutch pack was indicative of the others. One was rubbish with lots of debris in the sump erc..the other 3/4 new spec and minor black in sump.

Not sure if you can rely on this totally tho!

May need to go further to be sure.

thanks for the input :-)
just before i finished for the day, i had a look at the next set of rings. not spring loaded so easy to pop out retaining ring etc. again the friction plate was o.k. steels had same type of discolouration. again the width was within spec. almost new. what i did notice was that after all the oil has drained, every surface has a coating of very fine particles. even if everything is ok, i wonder if its worth stripping , cleaning , rebuilding etc. or just change filter / oil a few times to flush everything out. ?? gofer -)

Originally Posted by gofer

thanks for the input :-)
just before i finished for the day, i had a look at the next set of rings. not spring loaded so easy to pop out retaining ring etc. again the friction plate was o.k. steels had same type of discolouration. again the width was within spec. almost new. what i did notice was that after all the oil has drained, every surface has a coating of very fine particles. even if everything is ok, i wonder if its worth stripping , cleaning , rebuilding etc. or just change filter / oil a few times to flush everything out. ?? gofer -)

youve opened the box, clean it all out.