ZF external cooler install and transmission service - How to

[Schtoo]

Thanks to all for this, as I'm doing this over the next month or so myself and at the moment accruing the required bits and pieces trying to avoid getting anything that's questionable, and as little waste as possible. I've almost convinced myself there's no cheap/good way to do the trans connections, even making up my own fittings will end up being a waste of time/effort/money. Disappointing when the fittings to get out of the trans will be over $100 and a simple lathe job, but brass aint cheap and neither are viton o rings. Plus if I goof, where I'll be doing the job and where the lathe is are 30 minutes drive apart. And I'll be doing a full coolant and trans service at the same time, because why not? Replacing the entire cooling system aside from the heater core and the block.

 

All going in an FG ute, so I'll be tucking it up under the fuel filler. I'll try and take some pics along the way (using a scissor hoist, so room to move!) and write up my findings as I go along, many of which are addressed here (and why I'll add to the collection of info) but some which aren't. To be clear there, I've googled the crap out of it all, but I also got some info from the local folks at ZF which aren't so much 'secrets' as much as 'nobody asked'. Also why I have a 20l bucket of LG6 waiting for the job, don't ask how much it cost because you'll get right upset at me.

 

There is one thing however I wouldn't mind getting a 2nd/3rd/10th opinion on. At the moment, it has pink coolant in it, but signs it had green in it's past. Which one would be best, especially considering the heat exchanger is being deleted? Likely going green, but because I'm pulling it all out and can put in whatever I want I can go either way.

 

Stu.

[hjtrbo]

The coolant is an easy one. What ever the service manual says. 

 

And some happy pics of my ute trans cooler install. Went with a thermo fan cooler and thermo bypass valve.

 

 

 

 

 

 

 

 

[SirFaffer]

G'day mate.. just wondering how much all the parts cost you to do it? Cheers :)

[El Andrew]

Can't quite remember, but roughly:

$200 for cooler with fan
$70 for transmission fittings
Maybe another $70 for hose, clamps, wiring and switch
Don't worry about the thermo switch I used - waste of time
$200 for 20L transmission fluid

[Puffwagon]

1 hour ago, El Andrew said:

thermo switch I used - waste of time

 

Why?

[El Andrew]

Maybe I should have said "waste of time in a street car in Canberra". Mine turned on once in 6 years I reckon and even then the transmission was well within its safe range.

The manual override was a more useful option - I used to flick that on when the trans was warmed up and I was working it hard.

[Puffwagon]

Ah yeah that makes sense.

[bjc]

What lowest temp do you lot recommend before raping the ZF? My cold starts are usually 30°C being in NQ but the ZF gets to about 60-65°C quickly and then warm up is slow when cruising around town to get to operating temp of 78°C (thermostat is 82°C)...

[Puffwagon]

You want to have it within an adaptation range so it can adjust the pressures if necessary. There are multiple types of adaptation and subsequently various temp ranges for them.

 

Slipping adaptation starts at 70C, so it would be wise to wait until then before giving it the berries. To make things interesting there is a 3C hysteresis on the trans temp, so maybe wait until 73C lol.

[Schtoo]

Hmm. The fan controller has a spare relay. Maybe a small light on the NC contacts that goes out when it's up to proper temperature? Probably possible to run yellow when cold, green when happy and red when hot/fan running. I'll put that project on the list I think.

 

4 hours ago, SirFaffer said:

G'day mate.. just wondering how much all the parts cost you to do it? Cheers

I'll have to think about it, because I couldn't be stuffed looking it all up. Then could be less stuffed thinking about it, so looked it all up.

 

Cooler with fan; $200

Trans, cooler, etc. connections*; $286

Bypass; $129.

Fan controller; $75

(*Trans to AN x 2 $70, AN to Barb x 4 $110, temp probe inline fitting $23, hose clamps $20, hose $43, misc. $20.)

 

Total; $690

 

Plus 7l of LG6, filter, etc. for a service and additional for the larger volume due to lines, cooler, etc.

 

It's possible to be done cheaper, but mine sits under the tray, well up out of the way and protected. Bypass lets it warm up a little faster, which is important in Mel. and the fan has come on a few times, usually in traffic or on very hot days and/or a very heavy right foot.

 

If I had the means to see what the trans temp was while driving, I'd probably skip the controller and use a switch, but I'm also a big fan of letting something do jobs like that so I don't forget or miss a sign to intervene. A switch is a couple of $$, and a controller is $100, but the controllers sole job is watch the temp, make it cooler when needed and that's it. And $100 is cheaper than box full of burned fluid and clutches. If I'd taken a little more time to look at things, I would have got one of the cooler/fan units with a built in temp switch and left it at that. A bit simpler, cheaper and cleaner. Maybe the fluid would run hotter, but well within what it's happy to take.

 

Alternatively, you could run the cooler to the front of the car, skip the whole fan completely and slip in a bypass to make sure it actually gets to temp.