The V8 Owners Forum -

Some people say the oil flow reverses direction when the torque converter locks up and some say it doesn't - who is right?
I ask because the thermostat I was planning on using has ports marked in and out so if the flow does reverse this means the thermostat will be either the right way round or backwards depending on what the gearbox is doing.

I have to say that I have never heard that, and I can't find any mention in the manual that it does that.

But I also can't find any mention that it doesn't !!

It would be interesting to see some evidence on the subject.

Chris.

Not reverse direction, it diverts flow. Do a little Google, there is plenty of info there, bowlers website has a pretty good explanation.

All I've managed to find is some mention of the flow reversing on landyzone.co.uk and lr4x4.com forums. Also on a Volvo(?) or BMW(?) forum and an Australian Land Rover forum neither of which I can find again.
Do you have a link for the bowlers website? I've found Bowler Transmissions in Illinois USA but they don't mention ZF gearboxes.
I have tried emailing ZF and so far they haven't replied although I have found that big companies can be a bit slow with questions from individuals about older products.
However, I did find on their website that ZF stands for Zeppelin Foundation so next time someone asks about it I can say it's a Zeppelin gearbox

I dont know but I would think that if the fluid did reverse direction it would only be thru the converter. Just thinking that regardless of what its fitted to the likelyhood of there being a thermostatically controlled cooler is good .....ergo , it wouldnt make sense to reverse the flow thru the cooler when the converter locks up .
I bought a 4hp22 of a bmw and used a range rover bell housing and converter to fit it to my Rv8. Fluid exits the cooler and dumps straight into the pan so I dont see how it could reverse flow.